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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. I didn't try myself, but I don't see why this wouldn't work. Using a PC drive should be straightforward. It is certainly possible to connect to a 1050 (or 810) Atari drive, but has some issues. In first place you don't have the index pulse, which is, at least, important. In second place, you need to compensate for the different rotation speed, but this is not big deal. Last but not least, these Atari drives don't use the simple step motor control that more modern drives have. You need 4 pins/wires to control the 4 phases step motor. Note that a good logic analyzer, like the one Christian used in that article, is not much cheaper (if at all) than a SuperCard Pro.
  2. Thanks a lot . Mostly out of curiosity, do you know/remember which kind of duplicating equipment they used? I understand that Trace Mountain was the most common industrial duplicators at that period.
  3. Very interesting. Do you mind sharing some historical and anecdotal information? At which duplication company you worked? At the US or Europe? Do you remember which publishers used to duplicate disks at that company? Anything else interesting? Masters are rare indeed, but they appear occasionally. Of course, they are probably unique for those specific titles.
  4. After 10 years I am older and, honestly, I don't remember all the details , but ... Pokey is not designed for a true, full synchronous serial transfer. The so called synchronous mode is just the regular asynchronous mode with start and stop bits, only using an external clock instead of an internally generated one.
  5. I believe that was indeed the original reasons that sector copiers at that time had that option. Btw, the $1A hex is actually $E5 inverted, which is the actual data written to the disk surface. And not by chance it's the same value written normally when you format a floppy on a PC. In theory, the MFM pattern produced by $E5 is the most stressing to the magnetic surface. So the idea is that if you format the whole disk with that value and it can verified ok, then probably the disk is fine.
  6. I still believe that the original layout files should be made public. Even just for the historical value. Curt?
  7. This is not strictly related to the MOS process or the clocking system used at that time (called two phases non overlapped clock). Flip flops, memory bits, can be static or dynamic, as it happens with SRAM or DRAM chips respectively. Static memory holds the content with a voltage loop, dynamic memory just by capacitance and must be refreshed frequently enough. The same type of memory bits are used inside chips. If a chip uses only static flip flops, then it is fully static and it has no minimum clock frequency. That could have been implemented at the time with NMOS chips, but there was no interest in that feature, and would have been too expensive because static ram takes more transistors than dynamic ram. I reverse engineered the layout of the whole Atari 8 bit chipset. This is the main thread for ANTIC, with high rez die image, reverse engineered schematics and layout: The digitized layout was meant for reverse engineering the logic. Some work would be required to use for fabbing NMOS chips. At the time I didn't think somebody would be interested. And probably is better to use an FPGA/CPLD replacement instead of a full custom chip. Nowadays is no big deal to put a CPLD (non volatile FPGA) with voltage level shifters in a small board that would fit a DIP 40.
  8. Not sure that make much sense to me, does it? You want them to be free and public, but because somebody might/will/did use them closed, then you "close" them yourself? For years and years? You can't GPL something that is not yours. And even if you could, copyright has limited to no effect on hardware design. You can't copyright schematics. Well, you can copyright the particular drawing of the schematics in the best case, but not the actual design. Similarly for layout files. You can't even copyright Verilog or HDL files at the extent as if it they would be software. I went already all over this for my own decap and layout reverse engineering stuff. You just have to grow up and understand that releasing something to the public does have a price. Please note that "you" in this post is not you personally, but in a generic non personal sense. Anyway, most of this stuff at this point has more historic than technical value because most of the information, including layout, was already recovered by reverse engineering. They do belong to a public museum.
  9. I think I did interpret your comment correctly. I was just being ironic, sorry. Because, again, many of us asked for those files for years, both publicly and privately. So "he just asked him" doesn't sound a reasonable explanation for sharing the files with a single individual and not making them public. We are not talking about the schematics that he published. We are talking about the chip layout files, including those mentioned in this thread about GTIA and several other chips, still unreleased to the public. Sorry again for being ironic and not too polite. But I really can't understand why all those files aren't released to the public after all those years. Because of the historic and technical value they have, I honestly believe they really belong to the community.
  10. I guess you don't mean he specifically asked to share the files with him only and not make the public, do you? If you mean that he simply asked for the files, well ... as you can see at this very same thread, many of us have been asking for those chip layout files for years.
  11. Why he "shared" the GDS files just with you !!!??? Why not make then public? If he does I'm sure somebody, eventually, would be able to process them. And besides, the original GDS files are valuable by themselves to preserve them and make then public.
  12. I see. Didn't consider you were applying any skew.
  13. Not sure I understand why this would happen in this case when you converter from an ATR image. Don't you create SCP images already "correctly" aligned to the index so that writing blindly index to index would be ok? There is no skew in the ATR image to preserve anyway. I'm not saying that it is better to use SCP to write to the disk. Just commenting that it should be different in this case
  14. Doctor, I'm not sure you understand my point. But never mind, I don't want to hijack the thread. Keep up the good work, thanks.
  15. Yes, I can see what the listing posted here claims. But even that claim is a bit confusing. There was no Atari release on disk. The Atari release was, AFAIK, on cart only. The later Datasoft release was on disk. Note that the wording you are using here is not exactly the same as the listing. The listing claims "for Atari Inc". That's not the same as "for the Atari" as you are saying. In one case it seems to indicate the publisher, in the other the platform. Anyway, I'm not trying to play semantics or nitpick. Sorry if it sounded like that. And I'm no after anything in particular. I just was saying that, IMHO, we should be careful and precise with this sort of thing. May be because we were pissed off more than once with some announcements that original sources were found. But it turned out later that it was actually a reverse engineering work. Or even worse, it was original incomplete source mixed with disassembling, so you can't even tell which parts are original and which not.
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