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ijor

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ijor last won the day on July 31 2011

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About ijor

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  1. My personal opinion is that I'm not sure it is a so good idea. Of course that the topic is cool and there is enough interest. The question is if better to have a separate forum (subforum or not doesn't matter too much), or keep the topic in this generic 8-bit forum. IMHO, unless the volume is too high that you would better separate, I'd prefer not.
  2. The Archiver open code is not exactly a password for privacy purposes. The purpose was to defend against nasty software copy protections that might attempt to detect a custom drive and refuse to run intentionally. Each original Chip/Archiver came with a different open code that was provided by the manufacturer. But non original EPROMS, not being a boxed product, usually came with such an obvious open code intentionally. There is nothing wrong with that unless somebody will write modern software that would attack such an Archiver open code.
  3. The open code is different on each drive unit. It is a sort of serial number. That's the whole point. Archiver emulators, such as the one for the Happy, typically don't need an open code. They start already open. Archiver/The Chip clones usually have an "obvious" open code, such as 0000, 1234, or something like that. Please, please, DO NOT crosspost the same question on multiple threads.
  4. Exactly. Raw/low level dumping is density and encoding agnostic. And btw, the Catweasel didn't have an intrinsic limitation with double or enhanced densities. The problem with the Catweasel was that there wasn't a standard low level file format and then it usually required specific Catweasel tools.
  5. Well, I can't say I know for sure. Atari XL field service manual shows this pin as internally N.C. And on all the schematics I've (previously) seen it is indeed not connected. Now ... I just looked at the console schematics that also used Sally, 5200 and 7800. And according to those schematics both pins are connected one to the other, externally, at the board level. Not sure what this is supposed to mean ??? AFAIK, there is no Sally datasheet. Might be interesting to scope pin 34 and see if there is any output.
  6. Hi Jim, As I said before, that note claiming that pin 34 is also R/W has to be wrong. R/W seems to be at pin 36 only. HALT is asserted by ANTIC one cycle before the CPU should disconnect from the bus. Note that HALT might have almost half a cycle delay. There is an ANTIC datasheet here: As also already mentioned, the earlier 8-bit computers used a standard 6502 and the HALT logic was external. You can check the Atari 800 (or 400) schematics and you would see exactly the HALT logic. It just stops the clock at the right time when the 6502 releases the bus. These schematics are widely available, sometimes as part of the Atari Technical Reference Notes: http://www.atarimania.com/documents/atari-800-technical-reference-notes.pdf
  7. (Bolding is mine) It this actually true? All references claim pin 34 is N.C., implying R/W is connected to 36 pin instead (and not in addition) to pin 34.
  8. Let's not forget that, precisely because of the FP routines, it doesn't actually fit into 8K. It "borrows" an extra 2K ($D800-$DFFF) from the OS space.
  9. I suspect that the reasons weren't entirely technical. IIRC, Atari initially asked to SMI to port MS Basic, which would probably mean using MS FP routines. But they rejected the idea and offered to write a new Basic from scratch. Sounds like there were some commercial motivations for the whole approach.
  10. Back at the day we used Diskeeper. I seem to recall it needs translator though? http://a8preservation.com/#/software/title/2930
  11. May be you are not aware, but Happy 810 firmware is actually just the original Atari ROM patched. Almost all the original Atari code is there verbatim. We had a thread about that some time ago. We wondered if that was legal or not. If he received some kind of authorization from Atari (I really doubt that), and if Atari was aware about this at all. Very interesting again. Looking forward to actually test your code We might be able to do that under emulation.
  12. Synertek was an official second source for MOS. It used almost the same mask. But as said, you might be mixing up with CMOS variants. CMOS parts were a complete new design and they didn't implement the undoc opcodes. I don't remember hearing about any 6507 CMOS part though. May be you tested a Synertek CMOS 6502 somehow, and assumed 6507 Synertek NMOS (not CMOS) would behave the same? Very interesting. Seems you invested a lot of time and effort. Just out of curiosity, did you have any contact with the other people/companies involved in similar developments, like Happy, Spartan/ICD (The Chip/Archiver)? Thanks once again
  13. Hi James, Welcome and thanks a lot for your input. It is always so great to have information first hand from the original developers. And congratulations for what seems to be a great development. Guess you were unlucky and were a bit too late with Atari releasing the 1050 soon after your product. I don't have a Synertek 650X to actually try, but I'm not sure that can be right. All the original 650X manufacturers used (almost) the same fab mask provided by MOS. They only changed the branding at the metal layer. But they didn't developed their own version. All the undocumented opcodes should be supported. It was only years later, when they started manufacturing extended CMOS versions that they actually remade the design adding some new opcodes, and then the undocumented opcodes were gone. The undoc opcodes were used by several programs. If the Synertek doesn't implement them then it would be incompatible with all that software and we surely would have known. Both terms were sometimes used to refer to the same thing. Yes, skew was used mainly for the alignment between tracks. But unfortunately ICD use the expression "sector skew" to actually refer to sector interleave, introducing some confusion to the terminology. Not really. Most Atari 8-bit original disks, especially the older ones, were duplicated without physical alignment to the index hole. But, yes, many do were aligned and sometimes that was even used as part of the protection. Do you remember anything about the software to copy copy protected disks? Thanks again!
  14. Out of stock now. IIRC, there were about a dozen a few days ago ... guess the seller doesn't know why it suddenly sold out
  15. Is it really identical? The one pictured here doesn't seem to have an HDMI input ???
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