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shoestring

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Posts posted by shoestring

  2. Posted

    Based on experience, you may still get noise/jail bars coming through the display even with the SCCC / UAV installed if you don't have clean power or a decent ground from the vertical block.

     

    Once I fixed up the grounding issue, I had a very nice and clean picture on my 800 that surpasses the display in any of my other 8bits.

     

     

    • Like 2

  9. Posted

    I suppose it would only be an issue with a lot of upgrades ?

     

    I just have the SCCC which I purchased from you and the 800 doesn't draw too much. Though I believe this might change with someone like the Incognito.

     

    Just wondering if you still plan to develop the a personality board for the 800? I'll definitely be in line for one...

    • Like 2

  10. Posted · Edited by shoestring

    I'm hesitant on installing one inside my 800 for the same reason but since you've already done it you could try adding a choke ( just a hand wound ferrite core with 5 or 6 turns ) and a cap to implement a lc low pass filter.

     

    I had the same issue in another power supply I rebuilt but the symptoms were more subtle.

     

    Here's a really good video on how to implement one.

     

    https://www.youtube.com/watch?v=G-Llhy2ViUY

    • Like 3

  13. Posted

    I'd say in 1985 for Apple and Atari.

     

    Commodore started using them in 1986.

     

    The answer is probably here

     

    https://tedium.co/2016/11/24/1988-ram-shortage-history/

     

     

    After the computer industry slumped in 1985, prices for RAM chips fell to extreme lows. According to an analysis by retired computer science professor John C. McCallum, a 256-kilobit DRAM (dynamic random-access memory) chip being sold in BYTE magazine could be had for just $2.95 in September of 1985—a sharp decline from the $8.95 the same-capacity chip sold for in January of that year.

     

     

     

     

     

     

     

     

     

  14. Posted

    Here is my list of 20

     

    1. Wizball

    2. Uridium

    3. Murder On The Mississippi

    4. Maniac Mansion

    5. Paradroid

    6. Hunter's Moon

    7. Impossible Mission

    8. Pitstop II ( great with two players )

    9. Microprose Soccer

    10. Hardball

    11. Last Ninja

    12. Pacland

    13. International Karate + ( IK+ )

    14. Elite

    15. Bubble Bobble

    16. Little Computer People ( disk version )

    17. Prince Of Persia

    18. Bounder

    19. Spindizzy

    20. Barry McGuigan World Championship Boxing

    • Like 1

  15. Posted

    Kyle22 showed me this ad from 86 and they look relatively cheap.

     

    The two 8 Bit DRAMs are still cheaper based on this ad. I have no way of verifying when the board was made and I'm not sure when 4464s were introduced, so perhaps those were factors. 4416s were in the 600xl in 83, so its highly likely 4464s existed but may have been too expensive to manufacture in large enough quantities at the time. So perhaps availability was the main factor.

     

     

    post-13040-0-66599600-1455816203_thumb.p

  17. Posted · Edited by shoestring

    At least they used good quality RAM chips and not the mT variety we all love so much.

     

    I no longer have this board, the OKI branded ram went straight into an 800xl. I'm not sure why they didn't just use the two 4bit DRAMs and 3 wires.

     

    The ram upgrade before installing the Antonia 4Mb board.

     

    600xlupgrade.jpg

  21. Posted

    I can't check the schematics for the C64 at this moment, but I would say that C107 is not expendable :D

     

    Regarding the ceramic capacitors, I have seen arcade PCBs with lots of them not just chipped but broken, and they were still working. The problem with the board is that it may have some serious problems if some of the capacitors are in so bad state. But I would go with that board anyway: I would place C107 in its place, and check the main and second voltage on 6581 (SID): you should have +5 on pin 25 and +12v on pin 28. If you find this is correct, then you can move to check the ICs; if it is not, you have to take a further look on the supply side.

     

    Chipped is usually ok but I always check their values just in case they're off.

     

    I've only had one game ( it was a King Of Boxer ) constantly crash because of missing and broken decoupling caps. Once I replaced those the game was stable.

  23. Posted

     

    I just saw a video where a big portion of cheats and glitches work. Maybe these guys copy-pastad the source and jury rigged the system calls. Re-using actual SMB code would be a bad look.

     

    The cheats, glitches work because he took the original rom and reverse engineered the binary into his own source code.

     

    Whilst the game logic is the same. He would have re-written a large portion of the code to work around the c64s many limitations and make things work in a different way, each system is different with its own unique strengths. The scrolling relies on a very specific technique to make it work on the c64 and he also would have completely re-written the sprite engine to handle as many objects as it does.

     

    The sound & music would have been a challenge as well but the SID and NES APU can produce similar sounds.

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