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#isa — Public Fediverse posts

Live and recent posts from across the Fediverse tagged #isa, aggregated by home.social.

  1. 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/C7

    There 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 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
  2. 1993, France 🇫🇷
    CELOGIC développe un "PC chantier" :
    PC transportable durci industriel
    Une autre époque du hardware, plus proche de l’instrumentation que du computing grand public.

    As-tu connu cette french tech massive ?

    #RetroComputing #IndustrialPC #ISA #MadeInFrance #Telecom #HardwareHistory

  3. Traders placed over $1bn in perfectly timed bets on the Iran war

    Suspicious wagers on the US-Israel war in Iran are creating huge windfalls and raising concerns among lawmakers

    theguardian.com/world/2026/apr

    #Iran #ISA #Israel #war #betting #gambling #dystopia #corruption #PolyMarket

  4. Viele 🚗 🚚 🚗 treffen sich gerade auf der A3: Nürnberg -> Passau, zwischen 3.0 km hinter Spitzig Berg und 3.6 km vor Kühberg und blockieren die #Autobahn.

    Es könnte sein, dass sie heute die #EU-weit verpflichtende Installation eines intelligenten, übersteuerbaren Geschwindigkeitsassistenten in alle #Neufahrzeuge fordern. Das könnte langfristig die Zahl der #Verkehrstote​n um 20% reduzieren. Viel weniger Autos hätten #Totalschaden. 🚗⚠️ #Verkehrssicherheit #ISA (Quelle: ETSC)

  5. @IngridHbn ik mag toch hopen dat deze organisatie ook een dag van de lage motorkap, van de lichte auto, van de auto zonder videoscherm, met automatische niet omgaanbare snelheidsbeperking instelt?
    Het is bijvoorbeeld toch niet ongemerkt voorbij gegaan dat de USA aan Europa monstertrucks probeert op te dringen? Je weet wel, laaghangend fruit, oorzaken aanpakken ipv dweilen met de kraan open. #ISA #SUV

  6. Mistähän tulee sanonta, että joku asia ”tekee eetvarttia”? Kuka se Edward / Edvard on? Mutta #isä sanoi joskus niin. Nyt tekee eetvarttia olla lomalla. #fensterfreitag

  7. Muslims should follow Jesus, as the Quran clearly states that those who follow Jesus shall be superior to those who do not believe!

    john1126.com/721

    #Muslims #Jesus #Isa #Quran #Islam #Koran

  8. Viele 🚗 🚚 🚗 treffen sich gerade auf der A3: Nürnberg -> Passau, zwischen 3.0 km hinter Spitzig Berg und 3.6 km vor Kühberg und blockieren die #Autobahn.

    Es könnte sein, dass sie heute die #EU-weit verpflichtende Installation eines intelligenten, übersteuerbaren Geschwindigkeitsassistenten in alle #Neufahrzeuge fordern. Das könnte langfristig die Zahl der #Verkehrstote​n um 20% reduzieren. Viel weniger Autos hätten #Totalschaden. 🚗⚠️ #Verkehrssicherheit #ISA (Quelle: ETSC)

  9. RE: fosstodon.org/@golemwire/11507

    I'm starting a Fluxer (Discord alternative) group for my computing environment :D

    Invite link: fluxer.gg/I2P03SBv

  10. Знакомство с ретро-ПК. Оживляем раритетный Pentium-200

    Приветствую всех! Бывало ли у вас такое, что какой-то артефакт долгое время лежал у вас в надежде, что когда-нибудь пригодится, и наконец-таки получал своё применение? Именно такой и оказалась судьба данного компьютера. Когда-то давно именно с этого ПК у меня и началось знакомство со старым компьютерным железом. И вот сейчас мне наконец захотелось показать этот девайс и то, на что он вообще способен. Press F1 to continue

    habr.com/ru/companies/timeweb/

    #timeweb_статьи #asus #pentium #s3_virge #windows_98 #windows_xp #windows_2000 #msdos #isa #sound_blaster

  11. Viele 🚗 🚚 🚗 treffen sich gerade auf der A7: Kassel -> Hannover, zwischen 5.8 km hinter AS Nörten-Hardenberg und 1.9 km vor AS Northeim-West und blockieren die #Autobahn.

    Es könnte sein, dass sie heute die #EU-weit verpflichtende Installation eines intelligenten, übersteuerbaren Geschwindigkeitsassistenten in alle #Neufahrzeuge fordern. Das könnte langfristig die Zahl der #Verkehrstote​n um 20% reduzieren. Viel weniger Autos hätten #Totalschaden. 🚗⚠️ #Verkehrssicherheit #ISA (Quelle: ETSC)

  12. Выход в интернет с ПК на i486DX4 в 2026 году

    Приветствую всех! Думаю, всем нам известно: ещё каких-то лет десять назад "компьютером для интернета" назывался очень бюджетный офисный ПК, тогда как теперь потребление ресурсов возросло настолько, что порой современный веб - чуть ли единственное, с чем не справляется тот или иной девайс. А как насчёт чего-то совсем старого? Можно ли выйти в сеть с компьютера тридцатилетней давности и остались ли ещё какие-то сайты, которые можно полноценно просматривать с такого ПК? Сейчас и узнаем... Вставьте диск Windows 98SE и нажмите Enter

    habr.com/ru/companies/timeweb/

    #timeweb_статьи #486 #ne2000 #isa #pnp #сетевая_карта #windows_98 #msdos #свитч #блок_питания

  13. Может ли устареть инкремент: обзор выполнения оператора на современных вычислительных платформах

    Привет, Хабр! В ходе своей работы я часто изучаю сам и обучаю других писать и оптимизировать код. Однако когда я рекомендую в своих материалах «делайте так», я не всегда уверен, что тиражирую актуальную и достоверную информацию. Для подтверждения своих слов я изучаю и цитирую авторитетные источники, рекомендуемые в подборках книг, материалах конференций и курсах по C и C++. Тем не менее этого оказывается недостаточно. Скачав и углубившись в руководства по архитектуре, системам команд и оптимизации с официальных сайтов производителей вычислительных устройств, я обнаруживаю, что информация расходится. Возникает проблема: я перестаю чувствовать уверенность в своём опыте и в материале, который хотел тиражировать другим. В этой статье мы разберём один из таких примеров. Возьмём небольшой пример кода, сформируем рекомендации по его эффективному написанию и оценим, насколько сложно (и возможно ли вообще) обосновать их применение. Для этого мы проанализируем рекомендации учебников по программированию, оценим их качество и актуальность. Если они окажутся недостаточными, то обратимся к руководствам производителей «железа». Рассмотрим «простой» пример цикла, выполняющего сложение двух массивов. Слово «простой» взято в кавычки не случайно. Даже тезисное обсуждение эффективных методов сложения массивов на GPU (NVIDIA или AMD) с коллегами занимает несколько часов. Полноценно раскрыть эту тему в одной статье невозможно. Поэтому сосредоточимся лишь на части примера – операции инкремента «i++» в управляющей части цикла. Для анализа обратимся к книгам, рекомендованным на профильных it-ресурсах: Хабр, Яндекс.Практикум, Proglib и др. Чтобы уточнить информацию, рассмотрим официальные руководства следующих производителей вычислительных устройств: CISC (Intel, AMD), VLIW (МЦСТ, Texas Instruments), RISC (Apple, Qualcomm, MediaTek и др.) и GPU (NVIDIA, AMD).

    habr.com/ru/articles/983566/

    #isa #cpu #gpu #risc #cisc #vliw #программирование

  14. I got about $90 worth of 74-series chips, and am working on designing an architecture for it.
    I've done some basic design before, but have trouble designing ISAs where pointers are larger than the word size. So, I've never really made an 8-bit architecture I've liked.
    I designed a really simple 16-bit arch which I wanted to use, but I don't have enough chips! So I'm having to try to make an 8-bit arch....

  15. Lessons from History: When Workers’ Struggle Stopped Wars

    As we have explained in other articles in this issue of International Marxism, war and militarism are an inextricable part of imperialism.

    internationalsocialist.net/202

    #news #press #venezuela #democracy #workers #uspolitics #usa #isa #capitalism #marxism #imperialism #war

  16. #SouthKorea will be the first country that will truly have #DigitalSovereignty - thanks to it's major monopoly called #Samsung.

    We know next to nothing about the upcoming #SoC - or it's #ISA. But we're told it's an in-house #CPU & #GPU, which is good?

    I mean competition is always good, but it's Samsung we're talking about.

    Samsung reportedly plans a return to custom CPU and GPU cores for the Exynos 2800 - NotebookCheck.net News
    notebookcheck.net/Samsung-repo
    #tech

  17. @EH_Ludwigsburg

    Vielen herzlichen Dank & Zustimmung - Danke, dass Ihr im #Fediversum präsent seid und auch damit ein gutes Beispiel gebt!

    Aus der christlichen Tradition habe ich beispielsweise die #Martinstag -Umzüge als positive #Mimesis betont: Rabbi #Jesus (hebr. #Jehoschua , arab. #Isa) offenbart sich im Armen und Hilfsbedürftigen Menschen. Das ist eine weit über die #Religion hinaus mimetische Botschaft!

    @gedenkstaette_grafeneck

    youtube.com/shorts/B0CSD4BFkvo

  18. Aina puhutaan Pohjois-Pohjanmaan lestisnaisten kohtalosta synnytyskoneina.

    Sama ehkäisynvastainen meno on ruotsinkielisellä biblelbältetillä, jonka ydin #Luoto on (josta #KD:n Peter #Östman on kotoisin).

    #Bibelbältet kuuluu myös keskeisimpiin #hopeavesi- ja rokotevastaisuusalueisiin Suomessa.

    Maksumuuri, mutta otsikko ja kuva paljastavat kaiken - varsin nuoren näköinen 11 lapsen #isä. #Lapset selvästi syntyneet peräkanaa.

    osterbottenstidning.fi/Artikel

    #uskonto #Larsmo #raamattuvyöhyke #ehkäisy

  19. #Isänpäivä:

    Onko vieläkin niin, kuten oli joitain vuosia sitten, että kun isänpäivä lähestyy, alkavat #kirjakaupat ja marketit mainostaa isänpäivälahjaksi sotakirjoja?

    En tiijä, kun en kohtaa mainontaa oikein missään. Ja kyllä, olen tilanteeseen hyvin tyytyväinen.

    Se oli vaan ilmiönä NIIN hämmentävä.

    #sotakirja #sotakirjat #isänpäivälahja #lahja #kirja #kirjat #KirjaMasto #KirjaMastodon #isä #isät #pappa #papat #isi #isit #faija #faijat

  20. Unessa #isä'ni (k. 2003) kyseli isoveljeltään, mitä tämä oli pitänyt lahjaksi saamastaan #sinihomejuusto'sta. Oli ollut kuulemma oikein hyvää punkun kanssa, tämä totesi, mutta sitten isäni pudotti pommin: #juusto olikin löytynyt kotoa pakastimesta, ja sen viimeinen myyntipäivä oli ollut vuosikymmen takaperin. Oli vain kiinnostanut, olisiko se yhä lainkaan syötävää. #unet #setä #pakastin

  21. (29 Aug) Higher ed association will no longer host conferences in Ohio due to state’s anti-LGBTQ+ laws

    thebuckeyeflame.com/2025/08/29

    Archive: ais: archive.md/wip/yrK0S ia: s.faithcollapsing.com/478kk

    #cleveland #education #gay-ohio #gov.-mike-dewine #higher-education #international-studies-association #isa #lgbt-ohio #lgbtq-ohio #mj-bosia #policy-legislation #transgender-ohio

  22. South Korea’s Individual Savings Account (ISA) deposits exceeded 40 trillion won for the first time, with a record 7.5 trillion won increase in the first half of 2024, driven by strong demand for investment brokerage-type accounts and expanded tax benefits.
    #YonhapInfomax #ISA #KoreaFinancialInvestmentAssociation #Deposits #TaxBenefits #BrokerageFirms #Economics #FinancialMarkets #Banking #Securities #Bonds #StockMarket
    en.infomaxai.com/news/articleV

  23. South Korea’s Individual Savings Account (ISA) deposits exceeded 40 trillion won for the first time, with a record 7.5 trillion won increase in the first half of 2024, driven by strong demand for investment brokerage-type accounts and expanded tax benefits.
    #YonhapInfomax #ISA #KoreaFinancialInvestmentAssociation #Deposits #TaxBenefits #BrokerageFirms #Economics #FinancialMarkets #Banking #Securities #Bonds #StockMarket
    en.infomaxai.com/news/articleV

  24. South Korea’s Individual Savings Account (ISA) deposits exceeded 40 trillion won for the first time, with a record 7.5 trillion won increase in the first half of 2024, driven by strong demand for investment brokerage-type accounts and expanded tax benefits.
    #YonhapInfomax #ISA #KoreaFinancialInvestmentAssociation #Deposits #TaxBenefits #BrokerageFirms #Economics #FinancialMarkets #Banking #Securities #Bonds #StockMarket
    en.infomaxai.com/news/articleV

  25. South Korea’s Individual Savings Account (ISA) deposits exceeded 40 trillion won for the first time, with a record 7.5 trillion won increase in the first half of 2024, driven by strong demand for investment brokerage-type accounts and expanded tax benefits.
    #YonhapInfomax #ISA #KoreaFinancialInvestmentAssociation #Deposits #TaxBenefits #BrokerageFirms #Economics #FinancialMarkets #Banking #Securities #Bonds #StockMarket
    en.infomaxai.com/news/articleV

  26. Maksumuuri, mutta hauska idea. Iskät on peristaneet cheerleader-joukkueen Raumalla.

    Tulee mieleen, kun aikanaan yhden frendin tytär harrasti muodostelmaluistelua, ja sitten siellä näiden tyttöjen iskät pitivät oman muodostelmaluisteluesityksen jossain tilaisuudessa. Oli tylliä ja sifonkia and.

    #harrastus #harrastukset #isä #isät #isyys #vanhemmat #vanhemmuus #cheerleading #urheilu #lapsi #lapset #Rauma

    hs.fi/suomi/art-2000011285774.

  27. I've been sitting on a redesign of my TurboXT addon (github.com/hkzlab/TurboXT_Addo) for the 5160 for a few months now.

    This one allows (or at least should) toggling the turbo either via external input (switch, 8255 pin), or via an I/O write.

    Might decide to just send it for print at the end of the month, with a slew of other boards. Depends on my willingness to suffer at the time of ordering.
    #ibm #pcxt #isa

  28. @m20k @moonchild (Of course, it depends a little on what you considered the "fundamental idea").

    If you take "SW #JIT and in-order #VLIW" as core, then, sure, that might not have scaled so well, but if the core idea is "amortize #translation into a different #ISA", then a lot of #µOp caches can considered to already be there.

    #NVIDIA significantly improved the cold code performance in Denver though.

  29. How many #space agencies did you know ?
    #ASAL 🇩🇿 #GGPEN 🇦🇴 #CONAE 🇦🇷 #NSSA 🇧🇭 #AEB 🇧🇷 #CSA 🇨🇦 #CMSA #CNSA 🇨🇳 #DASHE 🇩🇰 #EgSA 🇪🇬 #ESAI 🇸🇻 #CNES 🇫🇷 #DLR 🇩🇪 #ISRO 🇮🇳 #LAPAN 🇮🇩 #ISA 🇮🇱 #ASI 🇮🇹 #JAXA 🇯🇵 #KENSA 🇰🇪 #LSA 🇱🇺 #AEM 🇲🇽 #NZSA 🇳🇿 #SUPARCO 🇵🇰 #CONIDA 🇵🇪 #PhilSA 🇵🇭 #KARI #KASI 🇰🇷 #ROSA 🇷🇴 #ROSCOSMOS 🇨🇳 #SSC 🇸🇦 #SANSA 🇿🇦 #CDTI 🇪🇸 #SSAU 🇺🇦 #UKSA 🇬🇧 #NASA 🇺🇸 #ZINGSA 🇿🇼 #APSCO #EUSPA 🇪🇺 #ESA 🇪🇺 unoosa.org/oosa/en/ourwork/spa

    #SpaceAgency

  30. How many #space agencies did you know ?
    #ASAL 🇩🇿 #GGPEN 🇦🇴 #CONAE 🇦🇷 #NSSA 🇧🇭 #AEB 🇧🇷 #CSA 🇨🇦 #CMSA #CNSA 🇨🇳 #DASHE 🇩🇰 #EgSA 🇪🇬 #ESAI 🇸🇻 #CNES 🇫🇷 #DLR 🇩🇪 #ISRO 🇮🇳 #LAPAN 🇮🇩 #ISA 🇮🇱 #ASI 🇮🇹 #JAXA 🇯🇵 #KENSA 🇰🇪 #LSA 🇱🇺 #AEM 🇲🇽 #NZSA 🇳🇿 #SUPARCO 🇵🇰 #CONIDA 🇵🇪 #PhilSA 🇵🇭 #KARI #KASI 🇰🇷 #ROSA 🇷🇴 #ROSCOSMOS 🇨🇳 #SSC 🇸🇦 #SANSA 🇿🇦 #CDTI 🇪🇸 #SSAU 🇺🇦 #UKSA 🇬🇧 #NASA 🇺🇸 #ZINGSA 🇿🇼 #APSCO #EUSPA 🇪🇺 #ESA 🇪🇺 unoosa.org/oosa/en/ourwork/spa

    #SpaceAgency

  31. How many #space agencies did you know ?
    #ASAL 🇩🇿 #GGPEN 🇦🇴 #CONAE 🇦🇷 #NSSA 🇧🇭 #AEB 🇧🇷 #CSA 🇨🇦 #CMSA #CNSA 🇨🇳 #DASHE 🇩🇰 #EgSA 🇪🇬 #ESAI 🇸🇻 #CNES 🇫🇷 #DLR 🇩🇪 #ISRO 🇮🇳 #LAPAN 🇮🇩 #ISA 🇮🇱 #ASI 🇮🇹 #JAXA 🇯🇵 #KENSA 🇰🇪 #LSA 🇱🇺 #AEM 🇲🇽 #NZSA 🇳🇿 #SUPARCO 🇵🇰 #CONIDA 🇵🇪 #PhilSA 🇵🇭 #KARI #KASI 🇰🇷 #ROSA 🇷🇴 #ROSCOSMOS 🇨🇳 #SSC 🇸🇦 #SANSA 🇿🇦 #CDTI 🇪🇸 #SSAU 🇺🇦 #UKSA 🇬🇧 #NASA 🇺🇸 #ZINGSA 🇿🇼 #APSCO #EUSPA 🇪🇺 #ESA 🇪🇺 unoosa.org/oosa/en/ourwork/spa

    #SpaceAgency