#pds — Public Fediverse posts
Live and recent posts from across the Fediverse tagged #pds, aggregated by home.social.
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a psd on steroids. maybe finally some good reasons to have one? #atproto #pds #usemycrab
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a psd on steroids. maybe finally some good reasons to have one? #atproto #pds #usemycrab
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a psd on steroids. maybe finally some good reasons to have one? #atproto #pds #usemycrab
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a psd on steroids. maybe finally some good reasons to have one? #atproto #pds #usemycrab
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40 seconds to install, configure a pds with a new atproto username fully plugged. #atproto #pds #usemycrab
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40 seconds to install, configure a pds with a new atproto username fully plugged. #atproto #pds #usemycrab
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40 seconds to install, configure a pds with a new atproto username fully plugged. #atproto #pds #usemycrab
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40 seconds to install, configure a pds with a new atproto username fully plugged. #atproto #pds #usemycrab
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wth, @[email protected] .. in my simple appview i use client side image resizer to avoid QUOTA EXCEEDED when my users want to upload 2,3,4.. pictures! UX, anybody? #atproto #bsky #pds #buildinpublic
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bash <(curl -fsSL raw.githubusercontent.com/isgudtek/myp...) 1 single line to install and configure a pds on linux/mac @mycrab.space. #pds #atproto #usemycrab
raw.githubusercontent.com/isgudtek/myp..... -
bash <(curl -fsSL raw.githubusercontent.com/isgudtek/myp...) 1 single line to install and configure a pds on linux/mac @mycrab.space. #pds #atproto #usemycrab
raw.githubusercontent.com/isgudtek/myp..... -
bash <(curl -fsSL raw.githubusercontent.com/isgudtek/myp...) 1 single line to install and configure a pds on linux/mac @mycrab.space. #pds #atproto #usemycrab
raw.githubusercontent.com/isgudtek/myp..... -
bash <(curl -fsSL raw.githubusercontent.com/isgudtek/myp...) 1 single line to install and configure a pds on linux/mac @mycrab.space. #pds #atproto #usemycrab
raw.githubusercontent.com/isgudtek/myp..... -
Tornado watch for portions of northeast Kansas and southeast Nebraska.
This is a Particularly Dangerous Situation. -
Tornado watch for portions of northeast Kansas and southeast Nebraska.
This is a Particularly Dangerous Situation. -
Tornado watch for portions of northeast Kansas and southeast Nebraska.
This is a Particularly Dangerous Situation. -
Tornado watch for portions of northeast Kansas and southeast Nebraska.
This is a Particularly Dangerous Situation. -
Tornado watch for portions of northeast Kansas and southeast Nebraska.
This is a Particularly Dangerous Situation. -
Surprisingly, Missouri's Grundy County has a scanner feed...
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Surprisingly, Missouri's Grundy County has a scanner feed...
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Surprisingly, Missouri's Grundy County has a scanner feed...
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Surprisingly, Missouri's Grundy County has a scanner feed...
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Surprisingly, Missouri's Grundy County has a scanner feed...
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PDS Flash Flood Emergency in Trenton, Missouri.
Flash Flood Warning
MOC079-170830-
/O.NEW.KEAX.FF.W.0016.260517T0235Z-260517T0830Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Kansas City/Pleasant Hill MO
935 PM CDT Sat May 16 2026...FLASH FLOOD EMERGENCY FOR SOUTHERN GRUNDY AND THE CITY OF TRENTON,
MO...The National Weather Service in Pleasant Hill has issued a
* Flash Flood Warning for...
Central Grundy County in north central Missouri...* Until 330 AM CDT.
* At 935 PM CDT, Emergency management reported thunderstorms
producing heavy rain across the warned area with numerous roads
flooded and some buckled. Between 5.5 and 7.5 inches of rain have
fallen. Another line of storms will bring additional extremely
heavy rainfall. The expected rainfall rate is 1.5 to 2.5 inches in
1 hour. Additional rainfall amounts of 2 to 4 inches are possible
in the warned area. Flash flooding is already occurring.FLASH FLOOD EMERGENCY for Southern Grundy and the City of Trenton,
MO. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND
NOW!HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.SOURCE...Emergency management reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets and underpasses.PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.Be especially cautious at night when it is harder to recognize the
dangers of flooding.&&
LAT...LON 4016 9376 4015 9339 3999 9339 4004 9376
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR$$
CDB
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PDS Flash Flood Emergency in Trenton, Missouri.
Flash Flood Warning
MOC079-170830-
/O.NEW.KEAX.FF.W.0016.260517T0235Z-260517T0830Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Kansas City/Pleasant Hill MO
935 PM CDT Sat May 16 2026...FLASH FLOOD EMERGENCY FOR SOUTHERN GRUNDY AND THE CITY OF TRENTON,
MO...The National Weather Service in Pleasant Hill has issued a
* Flash Flood Warning for...
Central Grundy County in north central Missouri...* Until 330 AM CDT.
* At 935 PM CDT, Emergency management reported thunderstorms
producing heavy rain across the warned area with numerous roads
flooded and some buckled. Between 5.5 and 7.5 inches of rain have
fallen. Another line of storms will bring additional extremely
heavy rainfall. The expected rainfall rate is 1.5 to 2.5 inches in
1 hour. Additional rainfall amounts of 2 to 4 inches are possible
in the warned area. Flash flooding is already occurring.FLASH FLOOD EMERGENCY for Southern Grundy and the City of Trenton,
MO. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND
NOW!HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.SOURCE...Emergency management reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets and underpasses.PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.Be especially cautious at night when it is harder to recognize the
dangers of flooding.&&
LAT...LON 4016 9376 4015 9339 3999 9339 4004 9376
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR$$
CDB
-
PDS Flash Flood Emergency in Trenton, Missouri.
Flash Flood Warning
MOC079-170830-
/O.NEW.KEAX.FF.W.0016.260517T0235Z-260517T0830Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Kansas City/Pleasant Hill MO
935 PM CDT Sat May 16 2026...FLASH FLOOD EMERGENCY FOR SOUTHERN GRUNDY AND THE CITY OF TRENTON,
MO...The National Weather Service in Pleasant Hill has issued a
* Flash Flood Warning for...
Central Grundy County in north central Missouri...* Until 330 AM CDT.
* At 935 PM CDT, Emergency management reported thunderstorms
producing heavy rain across the warned area with numerous roads
flooded and some buckled. Between 5.5 and 7.5 inches of rain have
fallen. Another line of storms will bring additional extremely
heavy rainfall. The expected rainfall rate is 1.5 to 2.5 inches in
1 hour. Additional rainfall amounts of 2 to 4 inches are possible
in the warned area. Flash flooding is already occurring.FLASH FLOOD EMERGENCY for Southern Grundy and the City of Trenton,
MO. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND
NOW!HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.SOURCE...Emergency management reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets and underpasses.PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.Be especially cautious at night when it is harder to recognize the
dangers of flooding.&&
LAT...LON 4016 9376 4015 9339 3999 9339 4004 9376
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR$$
CDB
-
PDS Flash Flood Emergency in Trenton, Missouri.
Flash Flood Warning
MOC079-170830-
/O.NEW.KEAX.FF.W.0016.260517T0235Z-260517T0830Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Kansas City/Pleasant Hill MO
935 PM CDT Sat May 16 2026...FLASH FLOOD EMERGENCY FOR SOUTHERN GRUNDY AND THE CITY OF TRENTON,
MO...The National Weather Service in Pleasant Hill has issued a
* Flash Flood Warning for...
Central Grundy County in north central Missouri...* Until 330 AM CDT.
* At 935 PM CDT, Emergency management reported thunderstorms
producing heavy rain across the warned area with numerous roads
flooded and some buckled. Between 5.5 and 7.5 inches of rain have
fallen. Another line of storms will bring additional extremely
heavy rainfall. The expected rainfall rate is 1.5 to 2.5 inches in
1 hour. Additional rainfall amounts of 2 to 4 inches are possible
in the warned area. Flash flooding is already occurring.FLASH FLOOD EMERGENCY for Southern Grundy and the City of Trenton,
MO. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND
NOW!HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.SOURCE...Emergency management reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets and underpasses.PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.Be especially cautious at night when it is harder to recognize the
dangers of flooding.&&
LAT...LON 4016 9376 4015 9339 3999 9339 4004 9376
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR$$
CDB
-
PDS Flash Flood Emergency in Trenton, Missouri.
Flash Flood Warning
MOC079-170830-
/O.NEW.KEAX.FF.W.0016.260517T0235Z-260517T0830Z/
/00000.U.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Kansas City/Pleasant Hill MO
935 PM CDT Sat May 16 2026...FLASH FLOOD EMERGENCY FOR SOUTHERN GRUNDY AND THE CITY OF TRENTON,
MO...The National Weather Service in Pleasant Hill has issued a
* Flash Flood Warning for...
Central Grundy County in north central Missouri...* Until 330 AM CDT.
* At 935 PM CDT, Emergency management reported thunderstorms
producing heavy rain across the warned area with numerous roads
flooded and some buckled. Between 5.5 and 7.5 inches of rain have
fallen. Another line of storms will bring additional extremely
heavy rainfall. The expected rainfall rate is 1.5 to 2.5 inches in
1 hour. Additional rainfall amounts of 2 to 4 inches are possible
in the warned area. Flash flooding is already occurring.FLASH FLOOD EMERGENCY for Southern Grundy and the City of Trenton,
MO. This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND
NOW!HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.SOURCE...Emergency management reported.
IMPACT...This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER
GROUND NOW! Life threatening flash flooding of low water
crossings, small creeks and streams, urban areas,
highways, streets and underpasses.PRECAUTIONARY/PREPAREDNESS ACTIONS...
Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.Be especially cautious at night when it is harder to recognize the
dangers of flooding.&&
LAT...LON 4016 9376 4015 9339 3999 9339 4004 9376
FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR$$
CDB
-
One thing I really like about ATProto/Atmosphere is the concept of a PDS, or Personal Data Server, storing all your account data.
The other day someone announced https://bookhive.buzz, basically ATProto take on https://bookwyrm.social, but unlike Bookwyrm, which requires you to create a separate account, Bookhive lets you log in with your PDS, most commonly your Bluesky account.
That's actually pretty neat.
And we could have something similar with Federated Credential Management (FedCM).
https://developer.mozilla.org/en-US/docs/Web/API/FedCM_API
Here's a GitHub issue requesting this for Mastodon:
https://github.com/mastodon/mastodon/issues/4800
#fediverse #mastodon #FedCM #indieauth #SocialMedia #ATProto #PDS
-
One thing I really like about ATProto/Atmosphere is the concept of a PDS, or Personal Data Server, storing all your account data.
The other day someone announced https://bookhive.buzz, basically ATProto take on https://bookwyrm.social, but unlike Bookwyrm, which requires you to create a separate account, Bookhive lets you log in with your PDS, most commonly your Bluesky account.
That's actually pretty neat.
And we could have something similar with Federated Credential Management (FedCM).
https://developer.mozilla.org/en-US/docs/Web/API/FedCM_API
Here's a GitHub issue requesting this for Mastodon:
https://github.com/mastodon/mastodon/issues/4800
#fediverse #mastodon #FedCM #indieauth #SocialMedia #ATProto #PDS
-
One thing I really like about ATProto/Atmosphere is the concept of a PDS, or Personal Data Server, storing all your account data.
The other day someone announced https://bookhive.buzz, basically ATProto take on https://bookwyrm.social, but unlike Bookwyrm, which requires you to create a separate account, Bookhive lets you log in with your PDS, most commonly your Bluesky account.
That's actually pretty neat.
And we could have something similar with Federated Credential Management (FedCM).
https://developer.mozilla.org/en-US/docs/Web/API/FedCM_API
Here's a GitHub issue requesting this for Mastodon:
https://github.com/mastodon/mastodon/issues/4800
#fediverse #mastodon #FedCM #indieauth #SocialMedia #ATProto #PDS
-
One thing I really like about ATProto/Atmosphere is the concept of a PDS, or Personal Data Server, storing all your account data.
The other day someone announced https://bookhive.buzz, basically ATProto take on https://bookwyrm.social, but unlike Bookwyrm, which requires you to create a separate account, Bookhive lets you log in with your PDS, most commonly your Bluesky account.
That's actually pretty neat.
And we could have something similar with Federated Credential Management (FedCM).
https://developer.mozilla.org/en-US/docs/Web/API/FedCM_API
Here's a GitHub issue requesting this for Mastodon:
https://github.com/mastodon/mastodon/issues/4800
#fediverse #mastodon #FedCM #indieauth #SocialMedia #ATProto #PDS
-
One thing I really like about ATProto/Atmosphere is the concept of a PDS, or Personal Data Server, storing all your account data.
The other day someone announced https://bookhive.buzz, basically ATProto take on https://bookwyrm.social, but unlike Bookwyrm, which requires you to create a separate account, Bookhive lets you log in with your PDS, most commonly your Bluesky account.
That's actually pretty neat.
And we could have something similar with Federated Credential Management (FedCM).
https://developer.mozilla.org/en-US/docs/Web/API/FedCM_API
Here's a GitHub issue requesting this for Mastodon:
https://github.com/mastodon/mastodon/issues/4800
#fediverse #mastodon #FedCM #indieauth #SocialMedia #ATProto #PDS
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This Trump Massie Epstein Situation Is Getting Crazier. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
This Trump Massie Epstein Situ... -
This Trump Massie Epstein Situation Is Getting Crazier. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
This Trump Massie Epstein Situ... -
This Trump Massie Epstein Situation Is Getting Crazier. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
This Trump Massie Epstein Situ... -
This Trump Massie Epstein Situation Is Getting Crazier. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
This Trump Massie Epstein Situ... -
https://www.europesays.com/at/154310/ Europa: Rumäniens Krise: Sozialdemokraten mit riskanter Strategie #Bolojan #EU #Europa #Europe #Krise #Misstrauensvotum #PDS #Rechtsextreme #Reformen #Rumänien #Sozialdemokraten #Stabilität
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PDS – the Programmers Development System – Part 3
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces
ZX Spectrum Interface
Here are the remade schematic and PCB for the ZX Spectrum target interface.
This is simply reproducing the schematic found on the CPC wiki, but now in KiCAD. There are a few extras, such as capacitors for the ICs and a pull-up resistor for the unused inverter. The equivalent PCB is shown below.
The PCB uses the ZX Spectrum Edge connector symbol and footprint from https://github.com/alvaroalea/8bits_kicad_libraries.
The jumpers in the top centre of the board use a custom footprint that mirrors the original PCB, but they can easily be replaced with standard pin-headers or even just a simple wire link.
Bill of Materials
- PDS Remake ZX Spectrum PCB
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- Resistors: 1K, 4K7, 10K
- Capacitors: 3x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- ZX Spectrum edge connector (straight)
I’m using a standard/common 56-pin edge connector socket which will have to be “doctored” to turn it into a ZX Spectrum compatible socket. There are notes on how to do this online, but I’ve not experimented yet.
Amstrad CPC Interface
This is very similar to the ZX Spectrum, but the address decoding gives it a different address (see part 1 for details).
The PCB is using a custom 2×25-way edge connector taken from the ZX Spectrum one used previously. It also uses the same custom jumpers as the ZX Spectrum version.
Bill of Materials
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- 74LS032 quad 2-input OR gate
- Resistors: 1K, 4x 4K7, 10K, 1M
- Capacitors: 4x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- 50-pin (2×25) edge connector (straight)
I think the edge connector will be a standard 2×25 way, 2.54mm pitch, edge connector socket that will look something like this:
But someone who knows about the Amstrad CPC will have to confirm this is the right one!
Conclusion
These boards come with a HUGE CAVEAT: they are completely untested and in the case of the Amstrad CPC version, a whole pile of ignorance, as I know effectively nothing about the machines.
I think I’ve got the edge connector in the correct orientation for both, but that is still to be verified.
I’ll probably build the spectrum version, but there is little reason for me to build the Amstrad one unless I can find a machine to try it on!
For now, these are just documenting the current state of play with remaking these boards.
All files are currently in a private GitHub directory as I’m not sure what the licensing issues are going to be. But if you’d like to collaborate with me on getting them built and tested, drop me an email and we can chat.
Kevin
#amstradCpc #pds #programmersDevelopmentSystem #z80Pio #zxSpectrum -
PDS – the Programmers Development System – Part 3
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces
ZX Spectrum Interface
Here are the remade schematic and PCB for the ZX Spectrum target interface.
This is simply reproducing the schematic found on the CPC wiki, but now in KiCAD. There are a few extras, such as capacitors for the ICs and a pull-up resistor for the unused inverter. The equivalent PCB is shown below.
The PCB uses the ZX Spectrum Edge connector symbol and footprint from https://github.com/alvaroalea/8bits_kicad_libraries.
The jumpers in the top centre of the board use a custom footprint that mirrors the original PCB, but they can easily be replaced with standard pin-headers or even just a simple wire link.
Bill of Materials
- PDS Remake ZX Spectrum PCB
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- Resistors: 1K, 4K7, 10K
- Capacitors: 3x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- ZX Spectrum edge connector (straight)
I’m using a standard/common 56-pin edge connector socket which will have to be “doctored” to turn it into a ZX Spectrum compatible socket. There are notes on how to do this online, but I’ve not experimented yet.
Amstrad CPC Interface
This is very similar to the ZX Spectrum, but the address decoding gives it a different address (see part 1 for details).
The PCB is using a custom 2×25-way edge connector taken from the ZX Spectrum one used previously. It also uses the same custom jumpers as the ZX Spectrum version.
Bill of Materials
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- 74LS032 quad 2-input OR gate
- Resistors: 1K, 4x 4K7, 10K, 1M
- Capacitors: 4x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- 50-pin (2×25) edge connector (straight)
I think the edge connector will be a standard 2×25 way, 2.54mm pitch, edge connector socket that will look something like this:
But someone who knows about the Amstrad CPC will have to confirm this is the right one!
Conclusion
These boards come with a HUGE CAVEAT: they are completely untested and in the case of the Amstrad CPC version, a whole pile of ignorance, as I know effectively nothing about the machines.
I think I’ve got the edge connector in the correct orientation for both, but that is still to be verified.
I’ll probably build the spectrum version, but there is little reason for me to build the Amstrad one unless I can find a machine to try it on!
For now, these are just documenting the current state of play with remaking these boards.
All files are currently in a private GitHub directory as I’m not sure what the licensing issues are going to be. But if you’d like to collaborate with me on getting them built and tested, drop me an email and we can chat.
Kevin
#amstradCpc #pds #programmersDevelopmentSystem #z80Pio #zxSpectrum -
PDS – the Programmers Development System – Part 3
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces
ZX Spectrum Interface
Here are the remade schematic and PCB for the ZX Spectrum target interface.
This is simply reproducing the schematic found on the CPC wiki, but now in KiCAD. There are a few extras, such as capacitors for the ICs and a pull-up resistor for the unused inverter. The equivalent PCB is shown below.
The PCB uses the ZX Spectrum Edge connector symbol and footprint from https://github.com/alvaroalea/8bits_kicad_libraries.
The jumpers in the top centre of the board use a custom footprint that mirrors the original PCB, but they can easily be replaced with standard pin-headers or even just a simple wire link.
Bill of Materials
- PDS Remake ZX Spectrum PCB
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- Resistors: 1K, 4K7, 10K
- Capacitors: 3x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- ZX Spectrum edge connector (straight)
I’m using a standard/common 56-pin edge connector socket which will have to be “doctored” to turn it into a ZX Spectrum compatible socket. There are notes on how to do this online, but I’ve not experimented yet.
Amstrad CPC Interface
This is very similar to the ZX Spectrum, but the address decoding gives it a different address (see part 1 for details).
The PCB is using a custom 2×25-way edge connector taken from the ZX Spectrum one used previously. It also uses the same custom jumpers as the ZX Spectrum version.
Bill of Materials
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- 74LS032 quad 2-input OR gate
- Resistors: 1K, 4x 4K7, 10K, 1M
- Capacitors: 4x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- 50-pin (2×25) edge connector (straight)
I think the edge connector will be a standard 2×25 way, 2.54mm pitch, edge connector socket that will look something like this:
But someone who knows about the Amstrad CPC will have to confirm this is the right one!
Conclusion
These boards come with a HUGE CAVEAT: they are completely untested and in the case of the Amstrad CPC version, a whole pile of ignorance, as I know effectively nothing about the machines.
I think I’ve got the edge connector in the correct orientation for both, but that is still to be verified.
I’ll probably build the spectrum version, but there is little reason for me to build the Amstrad one unless I can find a machine to try it on!
For now, these are just documenting the current state of play with remaking these boards.
All files are currently in a private GitHub directory as I’m not sure what the licensing issues are going to be. But if you’d like to collaborate with me on getting them built and tested, drop me an email and we can chat.
Kevin
#amstradCpc #pds #programmersDevelopmentSystem #z80Pio #zxSpectrum -
PDS – the Programmers Development System – Part 3
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces
ZX Spectrum Interface
Here are the remade schematic and PCB for the ZX Spectrum target interface.
This is simply reproducing the schematic found on the CPC wiki, but now in KiCAD. There are a few extras, such as capacitors for the ICs and a pull-up resistor for the unused inverter. The equivalent PCB is shown below.
The PCB uses the ZX Spectrum Edge connector symbol and footprint from https://github.com/alvaroalea/8bits_kicad_libraries.
The jumpers in the top centre of the board use a custom footprint that mirrors the original PCB, but they can easily be replaced with standard pin-headers or even just a simple wire link.
Bill of Materials
- PDS Remake ZX Spectrum PCB
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- Resistors: 1K, 4K7, 10K
- Capacitors: 3x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- ZX Spectrum edge connector (straight)
I’m using a standard/common 56-pin edge connector socket which will have to be “doctored” to turn it into a ZX Spectrum compatible socket. There are notes on how to do this online, but I’ve not experimented yet.
Amstrad CPC Interface
This is very similar to the ZX Spectrum, but the address decoding gives it a different address (see part 1 for details).
The PCB is using a custom 2×25-way edge connector taken from the ZX Spectrum one used previously. It also uses the same custom jumpers as the ZX Spectrum version.
Bill of Materials
- Z8420 Z80 PIO (NMOS is currently assumed given it has to work with a Z80A at 3.5MHz)
- 74LS245 octal bus transciever
- 74LS04 hex inverter
- 74LS032 quad 2-input OR gate
- Resistors: 1K, 4x 4K7, 10K, 1M
- Capacitors: 4x 100nF
- 6x6x6mm tactile button switch
- SPDT slider switch 2.54mm pitch OR 2.54mm header pins and jumper
- 16-way 2×8 shrouded pin header socket
- 50-pin (2×25) edge connector (straight)
I think the edge connector will be a standard 2×25 way, 2.54mm pitch, edge connector socket that will look something like this:
But someone who knows about the Amstrad CPC will have to confirm this is the right one!
Conclusion
These boards come with a HUGE CAVEAT: they are completely untested and in the case of the Amstrad CPC version, a whole pile of ignorance, as I know effectively nothing about the machines.
I think I’ve got the edge connector in the correct orientation for both, but that is still to be verified.
I’ll probably build the spectrum version, but there is little reason for me to build the Amstrad one unless I can find a machine to try it on!
For now, these are just documenting the current state of play with remaking these boards.
All files are currently in a private GitHub directory as I’m not sure what the licensing issues are going to be. But if you’d like to collaborate with me on getting them built and tested, drop me an email and we can chat.
Kevin
#amstradCpc #pds #programmersDevelopmentSystem #z80Pio #zxSpectrum -
Severe Weather Statement
National Weather Service Jackson MS
700 PM CDT Wed May 6 2026MSC037-070015-
/O.CON.KJAN.TO.W.0032.000000T0000Z-260507T0015Z/
Franklin MS-
700 PM CDT Wed May 6 2026...TORNADO EMERGENCY FOR Meadeville, Bude...
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 715 PM CDT FOR CENTRAL
FRANKLIN COUNTY...At 700 PM CDT, a confirmed large and destructive tornado was located
near Bude, or near Meadville, moving east at 50 mph.TORNADO EMERGENCY for Meadeville, Bude. This is a PARTICULARLY
DANGEROUS SITUATION. TAKE COVER NOW!HAZARD...Deadly tornado.
SOURCE...Radar confirmed tornado.
IMPACT...You are in a life-threatening situation. Flying debris may
be deadly to those caught without shelter. Mobile homes
will be destroyed. Considerable damage to homes,
businesses, and vehicles is likely and complete destruction
is possible.This tornadic thunderstorm will remain over mainly rural areas of
central Franklin County.PRECAUTIONARY/PREPAREDNESS ACTIONS...
To repeat, a large, extremely dangerous, and potentially deadly
tornado is on the ground. To protect your life, TAKE COVER NOW! Move
to an interior room on the lowest floor of a sturdy building. Avoid
windows. If in a mobile home, a vehicle or outdoors, move to the
closest substantial shelter and protect yourself from flying debris. -
PDS – the Programmers Development System – Part 2
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
Having now got a bit of an idea of how the PDS appears to work in my previous post (PDS – the Programmers Development System) I’m now taking another look at the PC interface and starting to think about the possibility of recreating the system.
The PC Interface
Having decided I couldn’t rely on the schematic on the CPC wiki, I’ve taken the printout-versions of the PCB traces and started tracing them through to see what is really going on. It was greatly helped by the PCB view that can be found here: https://lemmings.info/pds-programmers-development-system/
Of course, I am assuming here that the remade PC card does actually work.
It turns out the ISA to Intel 8255 part was fine, including the address decoding, but the three 8255 IO ports, through the octal line buffers, to the two PDS links are fundamentally missing some key links.
Essentially the three 74LS244s are configured for half in A->Y form and half in Y->A. The three IO ports (PORT A, B, C) are also split in half. This means that most of this circuit is working in 4-bit chunks.
The high level linkages are shown below.
So here we can see how the A halves of each of the 244s handles OUTPUT and the B halves handle INPUT. We can also see that U5 (sticking with the original schematic numbering for now) handles the control signals, U4 is D4-7 and U3 is D0-3. PORTC drives U5 and thus also handles all control signals.
We can also see that the data lines are now fully bidirectionally connected so that each can be connected to an OUTPUT or an INPUT depending on the state of the PC2 line. PORTB handles the OUTPUT and PORTA is the input.
The control signals are still mirrored as determined in the first part, but now we can see that some are OUTPUTs and some are INPUTs. The mappings from PC0-7 through to the link pins is shown below (note I’ve reverted to using the same PDS connector pin numbers as the ZX Spectrum schematic in the diagram above and table below).
PIODirectionLink 1 PinLink 2 PinPC0OUT313PC1OUT133PC2OUT1111PC3OUT99PC4IN515PC5IN155PC6IN7N/CPC7INN/C7There are two swapped pairs of connections, two common, and one unique to each.
As mentioned previously, the ZX Spectrum interface does not connect to pins 9,11,13,15 so that implies to me that it would not work out of link 2 without remapping in the software for the alternative pinout.
From working through the ZX Spectrum monitor code in part 1, we can infer the following functions:
- Pin 3 (OUT): PC to Target CLOCK
- Pin 5 (IN): Target to PC CLOCK/ACK
We can also note the following:
- Pin 11 (OUT): Direction based on PC2. HIGH = PC to Target; LOW = Target to PC
From this point I can now fully recreate the schematic and start to think about recreating the PCB.
The PC Hardware
One slight sticking point in remaking the PCB was getting useful dimensions for an XT era ISA card. Two useful references I found were:
- The ISA Spec can be found as part of the PC XT Technical Reference: https://bitsavers.org/pdf/ibm/pc/xt/6361459_PC_XT_Technical_Reference_Apr84.pdf
- Researched 8-bit ISA card dimensions: https://www.andavno.com/?p=87
The actual spec wasn’t massively useful to me. I don’t know if the ends of cards was slightly different in PC XT systems, but it doesn’t seem to match the photos of the PDS PC card. The second link was very well researched and complete however, so I went with that.
One compromise though was trying to keep the card within a 100x100mm footprint, so I’ve not extended completely to what I believe will be long enough to have an end plate.
The Schematic
The updated schematic is shown above. I’ve added a few things I’d expect to see on a modern design – additional 100nF capacitors (one for each IC), and a resistor network to pull up all unused inputs to the 74LS04.
I originally went with the ZX Spectrum version of the 16-way connector, but then when it came to assigning footprints, to get a right-angled IDC connector meant pin one was now in the wrong place, so I had to revert to the alternative pin numbering as per the original schematic.
The PCB
I’ve followed the original layout used on the PC card remake as far as possible, reasoning that the person who did this almost certainly knows a lot more about electronics than I do.
One thing I wasn’t sure about was a GND fill. I initially created a fill zone, but then decided I’d follow the original lead and use explicit GND connections. If someone advises that a fill will be better then it is pretty trivial to add in.
Other points to note:
- A already mentioned I’ve kept this within the 100x100mm footprint. This leaves two unknowns: will it be tall enough to be useful; and will it extend to the edge of a PC case?
- The two connectors extend beyond the edge of the PCB, so they hopefully will be available at the edge of a PC.
- The dimensions are such that more of the PCB is off to the right compared to the photos of the remade board I’ve seen.
This will do for now, but I think it is highly likely there will need to be some physical adjustments for this to be usable.
Conclusion
I believe I’ve got an accurate schematic for the board based on the photos available and I now have design for a candidate PCB. The problem is that I don’t know anything about what the software is expecting when it drives the Intel 8255 to work the PDS interface.
There is also the small matter of needing an ISA bus in a PC…
I’m hoping to get these boards published somewhere but right now, I’m not clear what the licensing issues would be. These boards are not available anymore, but at some point this was a company’s IPR.
For now, I’ll keep blogging observations and see what the interest is.
Next up will be some remake of the target PCBs.
Kevin
#intel8255 #ISA #pcXt #pds #programmersDevelopmentSystem -
PDS – the Programmers Development System – Part 2
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces.
Having now got a bit of an idea of how the PDS appears to work in my previous post (PDS – the Programmers Development System) I’m now taking another look at the PC interface and starting to think about the possibility of recreating the system.
The PC Interface
Having decided I couldn’t rely on the schematic on the CPC wiki, I’ve taken the printout-versions of the PCB traces and started tracing them through to see what is really going on. It was greatly helped by the PCB view that can be found here: https://lemmings.info/pds-programmers-development-system/
Of course, I am assuming here that the remade PC card does actually work.
It turns out the ISA to Intel 8255 part was fine, including the address decoding, but the three 8255 IO ports, through the octal line buffers, to the two PDS links are fundamentally missing some key links.
Essentially the three 74LS244s are configured for half in A->Y form and half in Y->A. The three IO ports (PORT A, B, C) are also split in half. This means that most of this circuit is working in 4-bit chunks.
The high level linkages are shown below.
So here we can see how the A halves of each of the 244s handles OUTPUT and the B halves handle INPUT. We can also see that U5 (sticking with the original schematic numbering for now) handles the control signals, U4 is D4-7 and U3 is D0-3. PORTC drives U5 and thus also handles all control signals.
We can also see that the data lines are now fully bidirectionally connected so that each can be connected to an OUTPUT or an INPUT depending on the state of the PC2 line. PORTB handles the OUTPUT and PORTA is the input.
The control signals are still mirrored as determined in the first part, but now we can see that some are OUTPUTs and some are INPUTs. The mappings from PC0-7 through to the link pins is shown below (note I’ve reverted to using the same PDS connector pin numbers as the ZX Spectrum schematic in the diagram above and table below).
PIODirectionLink 1 PinLink 2 PinPC0OUT313PC1OUT133PC2OUT1111PC3OUT99PC4IN515PC5IN155PC6IN7N/CPC7INN/C7There are two swapped pairs of connections, two common, and one unique to each.
As mentioned previously, the ZX Spectrum interface does not connect to pins 9,11,13,15 so that implies to me that it would not work out of link 2 without remapping in the software for the alternative pinout.
From working through the ZX Spectrum monitor code in part 1, we can infer the following functions:
- Pin 3 (OUT): PC to Target CLOCK
- Pin 5 (IN): Target to PC CLOCK/ACK
We can also note the following:
- Pin 11 (OUT): Direction based on PC2. HIGH = PC to Target; LOW = Target to PC
From this point I can now fully recreate the schematic and start to think about recreating the PCB.
The PC Hardware
One slight sticking point in remaking the PCB was getting useful dimensions for an XT era ISA card. Two useful references I found were:
- The ISA Spec can be found as part of the PC XT Technical Reference: https://bitsavers.org/pdf/ibm/pc/xt/6361459_PC_XT_Technical_Reference_Apr84.pdf
- Researched 8-bit ISA card dimensions: https://www.andavno.com/?p=87
The actual spec wasn’t massively useful to me. I don’t know if the ends of cards was slightly different in PC XT systems, but it doesn’t seem to match the photos of the PDS PC card. The second link was very well researched and complete however, so I went with that.
One compromise though was trying to keep the card within a 100x100mm footprint, so I’ve not extended completely to what I believe will be long enough to have an end plate.
The Schematic
The updated schematic is shown above. I’ve added a few things I’d expect to see on a modern design – additional 100nF capacitors (one for each IC), and a resistor network to pull up all unused inputs to the 74LS04.
I originally went with the ZX Spectrum version of the 16-way connector, but then when it came to assigning footprints, to get a right-angled IDC connector meant pin one was now in the wrong place, so I had to revert to the alternative pin numbering as per the original schematic.
The PCB
I’ve followed the original layout used on the PC card remake as far as possible, reasoning that the person who did this almost certainly knows a lot more about electronics than I do.
I’ve also tried to keep the connectors as close to the positions on the original as far as possible, whilst still keeping within the 100x100mm PCB total size.
One thing I wasn’t sure about was a GND fill. I initially created a fill zone, but then decided I’d follow the original lead and use explicit GND connections. If someone advises that a fill will be better then it is pretty trivial to add in.
Other points to note:
- A already mentioned I’ve kept this within the 100x100mm footprint. This leaves two unknowns: will it be tall enough to be useful; and will it extend to the edge of a PC case?
- The two connectors are roughly in the same horizontal position as the original card. They seem comparable to where the pins align with the edge connector anyway. An earlier iteration had them extending beyond the PCB, but I’ve redesigned it to mirror the original card.
- The dimensions are such that more of the PCB is off to the right compared to the photos of the original or the remade board I’ve seen.
- I’ve not been able to include mounting holes in any useful position whilst retaining the 100x100mm footprint.
The current dimensions of the above PCB are shown below.
This will do for now, but I think it is highly likely there will need to be some more physical adjustments at some point for this to be usable.
Conclusion
I believe I’ve got an accurate schematic for the board based on the photos available and I now have design for a candidate PCB. The problem is that I don’t know anything about what the software is expecting when it drives the Intel 8255 to work the PDS interface.
There is also the small matter of needing an ISA bus in a PC…
I’m hoping to get these boards published somewhere but right now, I’m not clear what the licensing issues would be. These boards are not available anymore, but at some point this was a company’s IPR.
For now, I’ll keep blogging observations and see what the interest is.
Next up will be some remake of the target PCBs.
Kevin
#intel8255 #ISA #pcXt #pds #programmersDevelopmentSystem -
PDS – the Programmers Development System – Part 2
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
Having now got a bit of an idea of how the PDS appears to work in my previous post (PDS – the Programmers Development System) I’m now taking another look at the PC interface and starting to think about the possibility of recreating the system.
The PC Interface
Having decided I couldn’t rely on the schematic on the CPC wiki, I’ve taken the printout-versions of the PCB traces and started tracing them through to see what is really going on. It was greatly helped by the PCB view that can be found here: https://lemmings.info/pds-programmers-development-system/
Of course, I am assuming here that the remade PC card does actually work.
It turns out the ISA to Intel 8255 part was fine, including the address decoding, but the three 8255 IO ports, through the octal line buffers, to the two PDS links are fundamentally missing some key links.
Essentially the three 74LS244s are configured for half in A->Y form and half in Y->A. The three IO ports (PORT A, B, C) are also split in half. This means that most of this circuit is working in 4-bit chunks.
The high level linkages are shown below.
So here we can see how the A halves of each of the 244s handles OUTPUT and the B halves handle INPUT. We can also see that U5 (sticking with the original schematic numbering for now) handles the control signals, U4 is D4-7 and U3 is D0-3. PORTC drives U5 and thus also handles all control signals.
We can also see that the data lines are now fully bidirectionally connected so that each can be connected to an OUTPUT or an INPUT depending on the state of the PC2 line. PORTB handles the OUTPUT and PORTA is the input.
The control signals are still mirrored as determined in the first part, but now we can see that some are OUTPUTs and some are INPUTs. The mappings from PC0-7 through to the link pins is shown below (note I’ve reverted to using the same PDS connector pin numbers as the ZX Spectrum schematic in the diagram above and table below).
PIODirectionLink 1 PinLink 2 PinPC0OUT313PC1OUT133PC2OUT1111PC3OUT99PC4IN515PC5IN155PC6IN7N/CPC7INN/C7There are two swapped pairs of connections, two common, and one unique to each.
As mentioned previously, the ZX Spectrum interface does not connect to pins 9,11,13,15 so that implies to me that it would not work out of link 2 without remapping in the software for the alternative pinout.
From working through the ZX Spectrum monitor code in part 1, we can infer the following functions:
- Pin 3 (OUT): PC to Target CLOCK
- Pin 5 (IN): Target to PC CLOCK/ACK
We can also note the following:
- Pin 11 (OUT): Direction based on PC2. HIGH = PC to Target; LOW = Target to PC
From this point I can now fully recreate the schematic and start to think about recreating the PCB.
The PC Hardware
One slight sticking point in remaking the PCB was getting useful dimensions for an XT era ISA card. Two useful references I found were:
- The ISA Spec can be found as part of the PC XT Technical Reference: https://bitsavers.org/pdf/ibm/pc/xt/6361459_PC_XT_Technical_Reference_Apr84.pdf
- Researched 8-bit ISA card dimensions: https://www.andavno.com/?p=87
The actual spec wasn’t massively useful to me. I don’t know if the ends of cards was slightly different in PC XT systems, but it doesn’t seem to match the photos of the PDS PC card. The second link was very well researched and complete however, so I went with that.
One compromise though was trying to keep the card within a 100x100mm footprint, so I’ve not extended completely to what I believe will be long enough to have an end plate.
The Schematic
The updated schematic is shown above. I’ve added a few things I’d expect to see on a modern design – additional 100nF capacitors (one for each IC), and a resistor network to pull up all unused inputs to the 74LS04.
I originally went with the ZX Spectrum version of the 16-way connector, but then when it came to assigning footprints, to get a right-angled IDC connector meant pin one was now in the wrong place, so I had to revert to the alternative pin numbering as per the original schematic.
The PCB
I’ve followed the original layout used on the PC card remake as far as possible, reasoning that the person who did this almost certainly knows a lot more about electronics than I do.
One thing I wasn’t sure about was a GND fill. I initially created a fill zone, but then decided I’d follow the original lead and use explicit GND connections. If someone advises that a fill will be better then it is pretty trivial to add in.
Other points to note:
- A already mentioned I’ve kept this within the 100x100mm footprint. This leaves two unknowns: will it be tall enough to be useful; and will it extend to the edge of a PC case?
- The two connectors extend beyond the edge of the PCB, so they hopefully will be available at the edge of a PC.
- The dimensions are such that more of the PCB is off to the right compared to the photos of the remade board I’ve seen.
- I’ve not been able to include mounting holes in any useful position whilst retaining the 100x100mm footprint.
This will do for now, but I think it is highly likely there will need to be some physical adjustments for this to be usable.
Conclusion
I believe I’ve got an accurate schematic for the board based on the photos available and I now have design for a candidate PCB. The problem is that I don’t know anything about what the software is expecting when it drives the Intel 8255 to work the PDS interface.
There is also the small matter of needing an ISA bus in a PC…
I’m hoping to get these boards published somewhere but right now, I’m not clear what the licensing issues would be. These boards are not available anymore, but at some point this was a company’s IPR.
For now, I’ll keep blogging observations and see what the interest is.
Next up will be some remake of the target PCBs.
Kevin
#intel8255 #ISA #pcXt #pds #programmersDevelopmentSystem -
PDS – the Programmers Development System – Part 2
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
Having now got a bit of an idea of how the PDS appears to work in my previous post (PDS – the Programmers Development System) I’m now taking another look at the PC interface and starting to think about the possibility of recreating the system.
The PC Interface
Having decided I couldn’t rely on the schematic on the CPC wiki, I’ve taken the printout-versions of the PCB traces and started tracing them through to see what is really going on. It was greatly helped by the PCB view that can be found here: https://lemmings.info/pds-programmers-development-system/
Of course, I am assuming here that the remade PC card does actually work.
It turns out the ISA to Intel 8255 part was fine, including the address decoding, but the three 8255 IO ports, through the octal line buffers, to the two PDS links are fundamentally missing some key links.
Essentially the three 74LS244s are configured for half in A->Y form and half in Y->A. The three IO ports (PORT A, B, C) are also split in half. This means that most of this circuit is working in 4-bit chunks.
The high level linkages are shown below.
So here we can see how the A halves of each of the 244s handles OUTPUT and the B halves handle INPUT. We can also see that U5 (sticking with the original schematic numbering for now) handles the control signals, U4 is D4-7 and U3 is D0-3. PORTC drives U5 and thus also handles all control signals.
We can also see that the data lines are now fully bidirectionally connected so that each can be connected to an OUTPUT or an INPUT depending on the state of the PC2 line. PORTB handles the OUTPUT and PORTA is the input.
The control signals are still mirrored as determined in the first part, but now we can see that some are OUTPUTs and some are INPUTs. The mappings from PC0-7 through to the link pins is shown below (note I’ve reverted to using the same PDS connector pin numbers as the ZX Spectrum schematic in the diagram above and table below).
PIODirectionLink 1 PinLink 2 PinPC0OUT313PC1OUT133PC2OUT1111PC3OUT99PC4IN515PC5IN155PC6IN7N/CPC7INN/C7There are two swapped pairs of connections, two common, and one unique to each.
As mentioned previously, the ZX Spectrum interface does not connect to pins 9,11,13,15 so that implies to me that it would not work out of link 2 without remapping in the software for the alternative pinout.
From working through the ZX Spectrum monitor code in part 1, we can infer the following functions:
- Pin 3 (OUT): PC to Target CLOCK
- Pin 5 (IN): Target to PC CLOCK/ACK
We can also note the following:
- Pin 11 (OUT): Direction based on PC2. HIGH = PC to Target; LOW = Target to PC
From this point I can now fully recreate the schematic and start to think about recreating the PCB.
The PC Hardware
One slight sticking point in remaking the PCB was getting useful dimensions for an XT era ISA card. Two useful references I found were:
- The ISA Spec can be found as part of the PC XT Technical Reference: https://bitsavers.org/pdf/ibm/pc/xt/6361459_PC_XT_Technical_Reference_Apr84.pdf
- Researched 8-bit ISA card dimensions: https://www.andavno.com/?p=87
The actual spec wasn’t massively useful to me. I don’t know if the ends of cards was slightly different in PC XT systems, but it doesn’t seem to match the photos of the PDS PC card. The second link was very well researched and complete however, so I went with that.
One compromise though was trying to keep the card within a 100x100mm footprint, so I’ve not extended completely to what I believe will be long enough to have an end plate.
The Schematic
The updated schematic is shown above. I’ve added a few things I’d expect to see on a modern design – additional 100nF capacitors (one for each IC), and a resistor network to pull up all unused inputs to the 74LS04.
I originally went with the ZX Spectrum version of the 16-way connector, but then when it came to assigning footprints, to get a right-angled IDC connector meant pin one was now in the wrong place, so I had to revert to the alternative pin numbering as per the original schematic.
The PCB
I’ve followed the original layout used on the PC card remake as far as possible, reasoning that the person who did this almost certainly knows a lot more about electronics than I do.
One thing I wasn’t sure about was a GND fill. I initially created a fill zone, but then decided I’d follow the original lead and use explicit GND connections. If someone advises that a fill will be better then it is pretty trivial to add in.
Other points to note:
- A already mentioned I’ve kept this within the 100x100mm footprint. This leaves two unknowns: will it be tall enough to be useful; and will it extend to the edge of a PC case?
- The two connectors extend beyond the edge of the PCB, so they hopefully will be available at the edge of a PC.
- The dimensions are such that more of the PCB is off to the right compared to the photos of the remade board I’ve seen.
This will do for now, but I think it is highly likely there will need to be some physical adjustments for this to be usable.
Conclusion
I believe I’ve got an accurate schematic for the board based on the photos available and I now have design for a candidate PCB. The problem is that I don’t know anything about what the software is expecting when it drives the Intel 8255 to work the PDS interface.
There is also the small matter of needing an ISA bus in a PC…
I’m hoping to get these boards published somewhere but right now, I’m not clear what the licensing issues would be. These boards are not available anymore, but at some point this was a company’s IPR.
For now, I’ll keep blogging observations and see what the interest is.
Next up will be some remake of the target PCBs.
Kevin
#intel8255 #ISA #pcXt #pds #programmersDevelopmentSystem -
PDS – the Programmers Development System – Part 2
This series of posts looks at the Programmers Development System (PDS).
- Part 1 – Introduction, background and some initial reverse engineering.
- Part 2 – A closer look at the PC ISA Interface card.
- Part 3 – Remaking the target interfaces.
Having now got a bit of an idea of how the PDS appears to work in my previous post (PDS – the Programmers Development System) I’m now taking another look at the PC interface and starting to think about the possibility of recreating the system.
The PC Interface
Having decided I couldn’t rely on the schematic on the CPC wiki, I’ve taken the printout-versions of the PCB traces and started tracing them through to see what is really going on. It was greatly helped by the PCB view that can be found here: https://lemmings.info/pds-programmers-development-system/
Of course, I am assuming here that the remade PC card does actually work.
It turns out the ISA to Intel 8255 part was fine, including the address decoding, but the three 8255 IO ports, through the octal line buffers, to the two PDS links are fundamentally missing some key links.
Essentially the three 74LS244s are configured for half in A->Y form and half in Y->A. The three IO ports (PORT A, B, C) are also split in half. This means that most of this circuit is working in 4-bit chunks.
The high level linkages are shown below.
So here we can see how the A halves of each of the 244s handles OUTPUT and the B halves handle INPUT. We can also see that U5 (sticking with the original schematic numbering for now) handles the control signals, U4 is D4-7 and U3 is D0-3. PORTC drives U5 and thus also handles all control signals.
We can also see that the data lines are now fully bidirectionally connected so that each can be connected to an OUTPUT or an INPUT depending on the state of the PC2 line. PORTB handles the OUTPUT and PORTA is the input.
The control signals are still mirrored as determined in the first part, but now we can see that some are OUTPUTs and some are INPUTs. The mappings from PC0-7 through to the link pins is shown below (note I’ve reverted to using the same PDS connector pin numbers as the ZX Spectrum schematic in the diagram above and table below).
PIODirectionLink 1 PinLink 2 PinPC0OUT313PC1OUT133PC2OUT1111PC3OUT99PC4IN515PC5IN155PC6IN7N/CPC7INN/C7There are two swapped pairs of connections, two common, and one unique to each.
As mentioned previously, the ZX Spectrum interface does not connect to pins 9,11,13,15 so that implies to me that it would not work out of link 2 without remapping in the software for the alternative pinout.
From working through the ZX Spectrum monitor code in part 1, we can infer the following functions:
- Pin 3 (OUT): PC to Target CLOCK
- Pin 5 (IN): Target to PC CLOCK/ACK
We can also note the following:
- Pin 11 (OUT): Direction based on PC2. HIGH = PC to Target; LOW = Target to PC
From this point I can now fully recreate the schematic and start to think about recreating the PCB.
The PC Hardware
One slight sticking point in remaking the PCB was getting useful dimensions for an XT era ISA card. Two useful references I found were:
- The ISA Spec can be found as part of the PC XT Technical Reference: https://bitsavers.org/pdf/ibm/pc/xt/6361459_PC_XT_Technical_Reference_Apr84.pdf
- Researched 8-bit ISA card dimensions: https://www.andavno.com/?p=87
The actual spec wasn’t massively useful to me. I don’t know if the ends of cards was slightly different in PC XT systems, but it doesn’t seem to match the photos of the PDS PC card. The second link was very well researched and complete however, so I went with that.
One compromise though was trying to keep the card within a 100x100mm footprint, so I’ve not extended completely to what I believe will be long enough to have an end plate.
The Schematic
The updated schematic is shown above. I’ve added a few things I’d expect to see on a modern design – additional 100nF capacitors (one for each IC), and a resistor network to pull up all unused inputs to the 74LS04.
I originally went with the ZX Spectrum version of the 16-way connector, but then when it came to assigning footprints, to get a right-angled IDC connector meant pin one was now in the wrong place, so I had to revert to the alternative pin numbering as per the original schematic.
The PCB
I’ve followed the original layout used on the PC card remake as far as possible, reasoning that the person who did this almost certainly knows a lot more about electronics than I do.
I’ve also tried to keep the connectors as close to the positions on the original as far as possible, whilst still keeping within the 100x100mm PCB total size.
One thing I wasn’t sure about was a GND fill. I initially created a fill zone, but then decided I’d follow the original lead and use explicit GND connections. If someone advises that a fill will be better then it is pretty trivial to add in.
Other points to note:
- A already mentioned I’ve kept this within the 100x100mm footprint. This leaves two unknowns: will it be tall enough to be useful; and will it extend to the edge of a PC case?
- The two connectors are roughly in the same horizontal position as the original card. They seem comparable to where the pins align with the edge connector anyway. An earlier iteration had them extending beyond the PCB, but I’ve redesigned it to mirror the original card.
- The dimensions are such that more of the PCB is off to the right compared to the photos of the original or the remade board I’ve seen.
- I’ve not been able to include mounting holes in any useful position whilst retaining the 100x100mm footprint.
The current dimensions of the above PCB are shown below.
This will do for now, but I think it is highly likely there will need to be some more physical adjustments at some point for this to be usable.
Conclusion
I believe I’ve got an accurate schematic for the board based on the photos available and I now have design for a candidate PCB. The problem is that I don’t know anything about what the software is expecting when it drives the Intel 8255 to work the PDS interface.
There is also the small matter of needing an ISA bus in a PC…
I’m hoping to get these boards published somewhere but right now, I’m not clear what the licensing issues would be. These boards are not available anymore, but at some point this was a company’s IPR.
For now, I’ll keep blogging observations and see what the interest is.
Next up will be some remake of the target PCBs.
Kevin
#intel8255 #ISA #pcXt #pds #programmersDevelopmentSystem -
The Epstein Note They Never Wanted Us To See. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
The Epstein Note They Never Wa... -
The Epstein Note They Never Wanted Us To See. #PDS Via @phillydefranco #Epstein #TrumpIsOnTheList #EpsteinList #EpsteinFiles #TrumpEpsteinFiles
The Epstein Note They Never Wa...