Bread80<p>Adding write support to the <a href="https://mstdn.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> in the simulator and <a href="https://mstdn.social/tags/CPC_ZERO" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CPC_ZERO</span></a>. The SYS register uses a '174. The clock pulse, to latch the data, could, naively, be driven by a write signal generated by PHI and RWB and gated by ~IO_SEL from the address decoder.</p><p>But the 6502 de-asserts RWB at the same moment it releases the data bus. Gate delays would mean the clock pulse arriving after the data bus has been released. Bus capacitance could make this work in the real world but I want proper validation. 1/n</p>
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root42<p>Five minutes until we code some <a href="https://chaos.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> assembly! Wait... I can't code 6502? Oh, never mind! We'll try anyway!</p>
Bread80<p>Old school DRAMs have a lot of timing requirements. I’ve been validating output from the <a href="https://mstdn.social/tags/CPCZERO" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CPCZERO</span></a> sequencer prototype against them - and everything checks out 🙂</p><p>Comments in my notes are where the timings depend on other components, such as the multiplexers.</p><p><a href="https://mstdn.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://mstdn.social/tags/Homebrewcomputer" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Homebrewcomputer</span></a> <a href="https://mstdn.social/tags/amstrad" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>amstrad</span></a></p>
oric_iss<p>I've just published the sources for <a href="https://mastodon.social/tags/QR_code" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>QR_code</span></a> generator adapted and optimized <a href="https://mastodon.social/tags/Oric" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Oric</span></a>,<a href="https://mastodon.social/tags/MOS6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>MOS6502</span></a>. Original code by: <span class="h-card" translate="no"><a href="https://mastodon.social/@the8bittheory" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>the8bittheory</span></a></span>. <br>LINK: 😎<a href="https://github.com/iss000/oricOpenLibrary/tree/main/lib-qrcode" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">github.com/iss000/oricOpenLibr</span><span class="invisible">ary/tree/main/lib-qrcode</span></a></p>
pagetable<p>6502 Illegal Opcodes in the Siemens PC 100 Assembly Manual (1980)<br><a href="https://www.pagetable.com/?p=1798" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="">pagetable.com/?p=1798</span><span class="invisible"></span></a><br><a href="https://mastodon.social/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a> <a href="https://mastodon.social/tags/aim65" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>aim65</span></a> <a href="https://mastodon.social/tags/siemens" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>siemens</span></a> <a href="https://mastodon.social/tags/pc100" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>pc100</span></a> <a href="https://mastodon.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a></p>
root42<p>Piers made a 6502 to 6504 adapter for the old CBM disk drives. Very neat!</p><p><a href="https://youtube.com/watch?v=fkwoDQRJFnA&si=nQ2RwQKieVUzPst5" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">youtube.com/watch?v=fkwoDQRJFn</span><span class="invisible">A&si=nQ2RwQKieVUzPst5</span></a> </p><p><a href="https://chaos.social/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a> <a href="https://chaos.social/tags/commodore" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>commodore</span></a> <a href="https://chaos.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a></p>
root42<p>Now <a href="https://chaos.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> seminar with svolli<br><a href="https://chaos.social/tags/Revision2025" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Revision2025</span></a></p>
root42<p>Thanks to svolli I now own two fake 65C02 -- which are actually real 6502! Oh how the tables have turned...<br><a href="https://chaos.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a></p>
Felix Palmen :freebsd: :c64:<p><span class="h-card" translate="no"><a href="https://fosstodon.org/@jbqueru" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>jbqueru</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.bsd.cafe/@gumnos" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>gumnos</span></a></span> <span class="h-card" translate="no"><a href="https://mastodon.bsd.cafe/@mms" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>mms</span></a></span> Well, it has a PC of course, which is technically an "address register" 😏 not a general-purpose one though.</p><p>Instructions are simple 8bit values (operation and mode combined to one opcode) and regarding which modes are available for which operation, I'd say you get quickly used to it. It's (partially) related to the purposes of the registers. None is really "general purpose", only A comes close, but yep, it can't do one thing X and Y can do: count.</p><p><a href="https://mastodon.bsd.cafe/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> coders use the "<a href="https://mastodon.bsd.cafe/tags/zeropage" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>zeropage</span></a>" in a way you'd otherwise use additional registers, which makes a lot of sense. The clocks for RAM and CPU are the same, RAM accesses need few clock cycles, and for the zeropage even fewer. There you can have your "address registers", 16 bits stored in little-endian.</p>
Laurent FRANCOISE<p>Je rattrape (un peu) mon retard dans les montages à assembler avec ces deux "NOP testers" pour <a href="https://piaille.fr/tags/z80" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>z80</span></a> et <a href="https://piaille.fr/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <br>Et un NOP testeur céquoidon ? C'est un montage qui permet de vérifier qu'un microprocesseur est vivant en présentant la commande NOP sur le bus de données (câblée en dur sur le circuit) et en regardant ce qu'il se passe sur le bus d'adresse : la commande NOP ne faisant rien le processeur passe juste à l'instruction suivante ce qui a pour effet d'incrémenter l'adresse, visualisée ici avec une série de LEDs.<br>L'horloge est ici un 555 pour que ça aille assez lentement pour y voir quelque chose !<br><a href="https://piaille.fr/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a></p>
𝚜𝚞𝚣𝚊<p><span class="h-card" translate="no"><a href="https://oldbytes.space/@EC64" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>EC64</span></a></span> PET meldet sich ♥️ <br><a href="https://mastodon.social/tags/vintagecomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vintagecomputing</span></a> <a href="https://mastodon.social/tags/commodore" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>commodore</span></a> <a href="https://mastodon.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://mastodon.social/tags/commodorepet" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>commodorepet</span></a> <a href="https://mastodon.social/tags/vcfe" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vcfe</span></a></p>
µP<p>Just received the "W.O.P.R. 64" cartridge for the <a href="https://mastodon.social/tags/C64" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>C64</span></a> expansion port. It features 32 LEDs to indicating signals on the <a href="https://mastodon.social/tags/MOS6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>MOS6502</span></a> address and data busses and for 8 control port indicators:</p><p><a href="https://www.tindie.com/products/thedarkforest/wopr64-for-commodore-64/" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://www.</span><span class="ellipsis">tindie.com/products/thedarkfor</span><span class="invisible">est/wopr64-for-commodore-64/</span></a></p><p><a href="https://mastodon.social/tags/RetroComputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RetroComputing</span></a> <a href="https://mastodon.social/tags/Commodore64" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Commodore64</span></a></p>
The Oasis BBS<p>Unearthing Commodore 64’s Hidden Illegal Opcodes<br><a href="https://techhub.social/tags/Commodore64" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Commodore64</span></a> <a href="https://techhub.social/tags/RetroProgramming" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RetroProgramming</span></a> <a href="https://techhub.social/tags/MOS6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>MOS6502</span></a> <a href="https://techhub.social/tags/C64" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>C64</span></a> <a href="https://techhub.social/tags/IllegalOpcodes" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>IllegalOpcodes</span></a> <a href="https://techhub.social/tags/VintageComputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>VintageComputing</span></a> <a href="https://techhub.social/tags/8bitMagic" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>8bitMagic</span></a> <a href="https://techhub.social/tags/IllegalOpcodes" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>IllegalOpcodes</span></a> <a href="https://techhub.social/tags/RetroComputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RetroComputing</span></a> <a href="https://techhub.social/tags/Assembler" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Assembler</span></a> <a href="https://techhub.social/tags/Coding" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Coding</span></a> <a href="https://techhub.social/tags/Secrets" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Secrets</span></a> <a href="https://techhub.social/tags/Retro" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Retro</span></a> <a href="https://techhub.social/tags/Hacking" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Hacking</span></a> <a href="https://techhub.social/tags/OldSchool" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>OldSchool</span></a><br><a href="https://theoasisbbs.com/unearthing-commodore-64s-hidden-illegal-opcodes/?feed_id=2467&_unique_id=67e69dd2278fc" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">theoasisbbs.com/unearthing-com</span><span class="invisible">modore-64s-hidden-illegal-opcodes/?feed_id=2467&_unique_id=67e69dd2278fc</span></a></p>
𝚜𝚞𝚣𝚊<p><a href="https://mastodon.social/tags/vcfe" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vcfe</span></a> <a href="https://mastodon.social/tags/vintagecomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vintagecomputing</span></a> <a href="https://mastodon.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://mastodon.social/tags/commodorepet" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>commodorepet</span></a> <a href="https://mastodon.social/tags/muenchen" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>muenchen</span></a></p>
𝚜𝚞𝚣𝚊<p>Mein PET hat gerade den nächsten Termin eingetippt: 3./4. Mai 2025 VCFe in München </p><p><a href="https://mastodon.social/tags/VCFe2025" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>VCFe2025</span></a> <a href="https://mastodon.social/tags/vintagecomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vintagecomputing</span></a> <a href="https://mastodon.social/tags/CommodorePET" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>CommodorePET</span></a> <a href="https://mastodon.social/tags/6502Forever" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>6502Forever</span></a> <a href="https://mastodon.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://mastodon.social/tags/vcfe24" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vcfe24</span></a> <a href="https://mastodon.social/tags/VCFe" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>VCFe</span></a> <a href="https://mastodon.social/tags/vintagecomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>vintagecomputing</span></a> <a href="https://mastodon.social/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a> <a href="https://mastodon.social/tags/muenchen" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>muenchen</span></a></p><p>Vintage Computer Festival Europa</p>
André Fachat<p>I am getting somewhere... <a href="https://mastodon.online/tags/8bit" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>8bit</span></a> <a href="https://mastodon.online/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a></p>
Atari Scene News<p>A webdemo dedicated to the MOS Technology 6502 microprocessor whose 50th anniversary we will celebrate this year, in the Sally version used in all <a href="https://mastodon.world/tags/Atari8bit" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Atari8bit</span></a> computers, original Atari 400/800 NTSC apart <a href="https://krystone.pl/6502/?Sally" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="">krystone.pl/6502/?Sally</span><span class="invisible"></span></a> <a href="https://mastodon.world/tags/atari" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>atari</span></a> <a href="https://mastodon.world/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://mastodon.world/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a></p>
Profoundly Nerdy<p>I've tried several disassembly and reverse engineering projects. I always get stuck and the projects peter out. I'm mostly interested in working <a href="https://bitbang.social/tags/C64" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>C64</span></a> binaries back to maintainable <a href="https://bitbang.social/tags/asm" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>asm</span></a> source code. Some people call this source code archaeology. I'm at least 0/5.</p><p>I've kept to 4-8kB binaries without copy protection. Nothing crazy. Any suggestions on RE workflow or anything else that will improve my odds of success?</p><p><a href="https://bitbang.social/tags/revereengineering" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>revereengineering</span></a> <a href="https://bitbang.social/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://bitbang.social/tags/retrocomputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>retrocomputing</span></a> <a href="https://bitbang.social/tags/programmimg" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>programmimg</span></a></p>
Paolo Amoroso<p>Nemanja Trifunovic argues that the 6502 is a good instruction set for learning to program in Assembly.</p><p><a href="https://nemanjatrifunovic.substack.com/p/6502-is-a-good-starting-point-for" rel="nofollow noopener" translate="no" target="_blank"><span class="invisible">https://</span><span class="ellipsis">nemanjatrifunovic.substack.com</span><span class="invisible">/p/6502-is-a-good-starting-point-for</span></a></p><p><a href="https://fosstodon.org/tags/mos6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>mos6502</span></a> <a href="https://fosstodon.org/tags/assembly" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>assembly</span></a> <a href="https://fosstodon.org/tags/programming" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>programming</span></a></p>
mmu_man<p>I was totally out but thanks to Sebastian we actually have a schedule for the <a href="https://m.g3l.org/tags/RetroComputing" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>RetroComputing</span></a> devroom at <a href="https://m.g3l.org/tags/FOSDEM" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>FOSDEM</span></a>!</p><p><a href="https://fosdem.org/2025/schedule/track/retrocomputing/" rel="nofollow noopener" target="_blank"><span class="invisible">https://</span><span class="ellipsis">fosdem.org/2025/schedule/track</span><span class="invisible">/retrocomputing/</span></a></p><p>Featuring <span class="h-card"><a href="https://ohai.social/@marquisdegeek" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>marquisdegeek</span></a></span> <span class="h-card"><a href="https://mastodon.social/@occitel" class="u-url mention" rel="nofollow noopener" target="_blank">@<span>occitel</span></a></span> 🙂 </p><p><a href="https://m.g3l.org/tags/DragonQuest" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>DragonQuest</span></a> <a href="https://m.g3l.org/tags/Teletext" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Teletext</span></a> <a href="https://m.g3l.org/tags/MOS6502" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>MOS6502</span></a> <a href="https://m.g3l.org/tags/Occitel" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>Occitel</span></a> <a href="https://m.g3l.org/tags/GameBoy" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>GameBoy</span></a> <a href="https://m.g3l.org/tags/SDCC" class="mention hashtag" rel="nofollow noopener" target="_blank">#<span>SDCC</span></a></p>
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