Image Map Image Map
Tab Content
  • iz8dwf's Avatar
    June 18th, 2017, 07:36 AM
    Also, double check that all the mask ROMs have known part numbers, check here: http://www.zimmers.net/anonftp/pub/cbm/firmware/computers/pet/ ...
    5 replies | 336 view(s)
  • iz8dwf's Avatar
    June 17th, 2017, 11:35 PM
    Hi, It surely is an 8032 motherboard. It has two option ROMs (the two EPROMs) so, if it were mine, I would dump all the ROMs and send the dumps to...
    5 replies | 336 view(s)
  • iz8dwf's Avatar
    June 14th, 2017, 02:53 AM
    iz8dwf replied to a thread Terninators for GVP SCSI in Commodore
    original SCSI bus is quite easy instead: BUS must be terminated at both ends (well, actually close enough to both ends, so a single internal drive...
    9 replies | 252 view(s)
  • iz8dwf's Avatar
    June 13th, 2017, 10:51 AM
    iz8dwf replied to a thread Terninators for GVP SCSI in Commodore
    That doesn't make much sense, an SD card *could* be used on a suitable SD->SCSI adapter, but that would surely need to comply with SCSI electrical...
    9 replies | 252 view(s)
  • iz8dwf's Avatar
    June 9th, 2017, 01:41 AM
    Hi, try with LCD contrast setting. I'm not sure where that is on the M100 (I only own a clone of it, the Olivetti M10), but what you describe looks...
    3 replies | 208 view(s)
  • iz8dwf's Avatar
    June 8th, 2017, 09:37 AM
    I doubt it's the VIC-II, but since the problem is temperature-dependent, try to get a compressed air can, even from ebay or so. It takes a few...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 6th, 2017, 11:10 AM
    Hi, the module in the last two pictures is a RAM module (3 x 8K), not ROM. I'm quite sure the "notch" of the module is on the same side as the top...
    4 replies | 167 view(s)
  • iz8dwf's Avatar
    June 6th, 2017, 06:54 AM
    Ram refresh cycles are generated by the VIC-II chip. It might fail to generate the refresh cycles only and keep on functioning normally on all the...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 4th, 2017, 11:29 PM
    The 8701 was used on late C64 and C64C motherboard. In the first three major revisions of the C64, there was a PLL clock generator made with a few...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 4th, 2017, 10:35 AM
    Yes, all it should need is a new clock generator. On the SX-64 there's a little daughterboad with one crystal oscillator and one VXO driven by a PLL....
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 4th, 2017, 09:24 AM
    Well, it's a really strange fault. Errors on all RAMs after some time. Why don't you get a compressed air can and try to spray one chip at a time...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 3rd, 2017, 11:47 AM
    1 flash = bit 7 failed. It can be either the ram chip UA4 (which according to your tests should be good) or some other IC on the data bus with stuck...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 2nd, 2017, 07:36 AM
    Runs fine in the kernel socket, see: https://youtu.be/x3suultS0dE?t=419 you need dead test.BIN image (found here as a zip file:...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 2nd, 2017, 04:24 AM
    I'm quite sure the dead test will show some RAM error, but if you tested all the RAM chips already, it won't help much at this point. What happens,...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 1st, 2017, 11:29 PM
    UB2 is a 74LS373, it's a de-multiplexer for the address lines to the color SRAM, it can't (easily) cause RAM problems. When insisting in socketing...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    June 1st, 2017, 12:42 AM
    Looks like temperature dependent, so it's quite easy to find the right chip(s) with the help of compressed air can. it easy enough to find,...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    May 31st, 2017, 12:09 AM
    Hi, indeed looks like the delete key is stuck. You can easily open the C64, there're only 3 screws on the bottom. You can try to disconnect the...
    3 replies | 146 view(s)
  • iz8dwf's Avatar
    May 30th, 2017, 12:02 AM
    You should really try to write a program that tests chunks of RAM (8K block at 49152 for example) for errors. Like writing all zeros and reading back...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    May 28th, 2017, 11:52 AM
    You're right, the ROMs are not the first thing that could produce a garbage screen, but I have developed a procedure that saves me as much guessing...
    38 replies | 1117 view(s)
  • iz8dwf's Avatar
    May 28th, 2017, 09:11 AM
    Hi, I would suspect a RAM and/or a RAM address multiplexer chip, or might also be the 6526 controlling the video memory bank. However you should...
    38 replies | 1117 view(s)
No More Results
About iz8dwf

Basic Information

Statistics


Total Posts
Total Posts
30
Posts Per Day
0.31
General Information
Last Activity
June 18th, 2017 07:36 AM
Join Date
March 20th, 2017
Referrals
0