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shoestring

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About shoestring

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    Dragonstomper

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    Male
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    Sydney
  • Interests
    C64, Apple, A8 & Amiga junkie. Video game & electronic repairs, homebrew dev (arcade diagnostics software), guitar & music.

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  1. That ‘joke of a general home computer’ happened to have sold 10s of millions of units. If it were really as bad as you say it was then they wouldn’t have sold nearly as many. It was great for the price, bundled with really good software and despite its shortfalls made home computing affordable for families like mine. During Christmas of 85, the IIe cost over $2500 AUD for basic system, the TI and the 800XL was in the $800-$900 price range and you just got the machine with a power supply + tv modulator . What did I get for $499? The c64, dataset unit, user guide, 4 really good programming books by Phil Cornes, 6 games plus a cart. Sounded like a much better deal to us and in hindsight it definitely was. That c64 lasted me until I bought an Amiga in 1990, so much for unreliability ? Regarding the cardboard shielding in the first models. Nobody ever seems to mention the proper metal shielding Commodore switched to in the later C models which also acted as a heat sink for all the major chips, increasing the reliability of the machine.
  2. I checked completed listings to see what these are fetching for these days on eBay AU. Ridiculous. I remember you couldn't even give these away. I picked up a working C128 for $5 at cash converters back in the mid 90s and there were breadbins & Cs taking up most of the rack space in the computing section. I bet most of them were thrown out. I should have bought the lot of them
  3. A bridge between pins 5 and 4 shouldn't damage the RAM. But you might want to check all of them again individually to make sure.
  4. Not sure where you going to get original non enhanced mask roms from. Alternatively, you can contact Steph at Eprompro and he can program the ROM chips you need. http://www.eprompro.com/computers.html
  5. 1. You don't need the original mask roms, you can program some EPROMs to take their place. There's a guy in Canada who does this as a service, just tell him what you need and provide the binaries and he will send you the chips. I believe you can use 2764s for video and program roms. But I'd save yourself the trouble and just get a kit from here for $25 which will end up being much cheaper. You get the roms, stickers and the 65C02 which will bring your machine up to Enhanced specs. https://www.reactivemicro.com/product/iie-enhancement-kit/ 2. If you think the issue is mechanical swap over the keyboard from your other IIe and see if the keys work .If its not a mechanical issue, reseat the keyboard decoder next to the connector ( UE14 ) or swap it and see if that resolves. Also check your ribbon cable as well.
  6. There's an issue with the boot sequence and the machine isn't starting. Check the F8 ROM first, then the AppleSoft ROM EF. ( locations D8 and D10 ). Did you remove all socketed chips prior to dishwashing ( that's never a good idea ) ?. Check that you didn't bend any pins re-seating. Similar issue at the link below with an Apple II & language card installed. So I would suspect the above ROMs or supporting logic fault. If replacing the ROMs doesn't fix it I'd suspect the two buffer ( 74LS244 ). If you have a scope or logic probe handy, you can check that the two enables are active ( pulsing ) on the above ROMs or just check the output of the MMU ( pin 19 and pin 20 ), if no pulsing then I'd assume replacement MMU is no good assuming the clock is good which appears it is. https://forums.macrumors.com/threads/apple-ii-plus-language-card-error-please-help.1699921/
  7. Does it beep with the speaker connected on reset or powering up ? Sounds like it's stuck in graphics mode. May be an issue with the logic chips which supports signals for softswitches. Check the IOU as well by substitution. Do you have a photo of the board and the screen ?
  8. Plenty of light is important too. I have a USB scope which helps locating these types of things. Is your c64 working now ?
  9. /RAS and A0 should not be bridged. Most likely happened when you installed the sockets. If they were not installed flush against the board, then it's likely solder has built up in between pins 4 and 5 on the component side and the two connections have been bridged.
  10. Not sure how I missed this one. They released it in January. Love the Drax tune.
  11. Yes. This is my 65XE below which I practically rebuilt ( if you're wondering about the sockets ). Atari did use the 130XE PCB in later 65XE models, presumably to save costs and just use the same PCB layout for both. As you can see the 2 other rams and EMMU are missing. And a 130XE with 4 x 4464 dram.
  12. This should also work in some XEs and the later Apple IIes ( Platinum board ) with the two 4464 DRAM configuration.
  13. a8diag1-6.rom CRC16 - E00A Some small fixes. 800XL PMG markers were completely off.
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