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sm3

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Posts posted by sm3

  2. Posted

    For the 1541, the relevant part of the ROM is

    F9E8 AD 00 1C LDA $1C00
F9EB 29 FB    AND #$FB   drive motor on
F9E0 8D 00 1C STA $1C00

    Seems I should be able to whip up an M-W and M-E for this. The 1571 appears to be the same for 1541-compatibility.

     

    Here is a BASIC version that will spin the motor:

     

    OPEN15,8,15:PRINT#15,"M-E"+CHR$(130)+CHR$(249):CLOSE15

     

    Found this on a website. Worked on my 1541. Don't forget to change the OPEN command to fit your drive device number.

    • Like 1

  6. Posted

    Wow nice, thanks! While I tend to use LDOS or LS-DOS on mine these days, I have fond memories of using TRSDOS 1.3 on a Model III the most.

     

    I spent (like most) many hours playing around with a Model III at my local Radio Shack after school. That 1.3 boot screen with the block graphical representation of a computer always brings back great memories!

     

    I still use both TRSDOS 2.7 and TRSDOS 1.3.

  9. Posted

     

    OLD CS1 wrote:

     

    > I found my MSD SD-2s, got them cleaned up and working.

     

    I had to have Ray Carlsen fix my MSD's. See

     

    http://blog.retro-link.com/2012/08/front-back-corroded-caps-and-others.html

     

    > ...one of the things I came across was that MSD made modifications to the TEC (TEAC?) FD-501 to accommodate GCR.

     

    It was TEC.

     

    > If true, does anyone have information on what had to be modified on the drive?

     

    I can't help you on that one.

     

    FCUG celebrating 33 years,

    Robert Bernardo

    Fresno Commodore User Group

    http://www.dickestel.com/fcug.htm

    July 18-19 Commodore Vegas Expo v11 -

    http://www.portcommodore.com/commvex

     

     

     

    Wow RobertB, you have quite the collection of MSD drives as well! I envy the storage space some of you seem to have for this type of thing ;)

  10. Posted

     

    Woot!

    attachicon.gifmsd sd-2.jpg

     

    I found my MSD SD-2s, got them cleaned up and working.

     

    I did a little research while I was cleaning them up. Given the schematics, like the 1541 there is no floppy controller chip. All work is done by the 6511Q and its I/O ports, similar to the 1541 and its 6522s. No hope in making the drive double-sided without a good bit of work: it looks like the 6511Q has a free I/O pin or two, so with some wiring and DOS modifications it may be possible to set up a head-select.

     

    That aside, one of the things I came across was that MSD made modifications to the TEC (TEAC?) FD-501 to accommodate GCR. None of this is mentioned in the schematics I have.

     

    If true, does anyone have information on what had to be modified on the drive?

     

     

    Those looks great! I bet they weigh quite a bit for shipping :)

  11. Posted

    That was my first guess (and post) as well but I figured I'd check mine first.

     

    There is a diagnostic program that is listed (BASIC) in the Sams Computerfacts for the Model 1 to check the video memory.

     

    There are other diagnostic programs as well available on the internet if you have the capability to transfer them to a disk or use them with a disk drive emulator.

     

    Here is where you can find the Sams Computerfacts among other things: http://www.classiccmp.org/cpmarchives/trs80/Library/Manuals/Hardware/

  12. Posted

    I've never really seen this issue myself (or noticed it). I think it probably happens so quickly that unless you take a picture of the monitor, you don't really see it. The screen has always sort of flickered with the graphics. I just chalk it up to being an over 38 year-old design.

     

    I'll need to set up my Model 1 to see if mine looks like that as well. I don't have enough room to keep all these old computers ready to use :)

     

    I use a device called the "MISE" so most of the time I don't even use the real TRS-80 monitor: http://home.comcast.net/~bartlett.p/MISE/

     

    Here he briefly talks about the black line: http://home.comcast.net/~bartlett.p/MISE/doc/vga.html

  15. Posted

    I know there are devices out there to warn you when the C64 decides to flake out, but is there a replacement for the C64 power brick that can avoid the issue all together?

     

    Yes, take a look at this page http://personalpages.tds.net/~rcarlsen/

     

    http://personalpages.tds.net/~rcarlsen/custom%20ps.html

     

    I have 2 of them (black/white metal box) that I use and recommend, but they aren't too cheap. I use one for a 64 and one for a 128.

     

    He has other versions, but I've only used the one in the black/white metal box myself.

     

    I wanted one that *only* has a 64 plug, so he built one with that specifically instead of the ones shown on the page that have multiple adapters. For the 128, he made an adapter that connects to the end of the 64 connector.

     

    These provide over 5 amps which is more than even a 128 power supply.

  17. Posted

    If you are using an original "brick" power supply, I would ask Ray to purchase one of his "64 savers". It's a device that keeps your original brick power supply from killing your 64 *when* it fails.

     

    He also sells new power supplies (switching type) but they are not too cheap. If you are serious about using a 64 you might want to invest in one. If you do go that route, you will not need the "64 saver". I have 2 of them myself and they work great!

  18. Posted

    Thanks guys

    The computer is going to be boxed up and shipped to Ray this weekend for him to work his magic on. Those traces for the hot ram chip are too tiny and delicate for my weary old eyes. Plus if the ram ain't the issue it will be in the hands of a guy who can fix it.

     

    I wouldn't be surprised if he repairs and mails it back to you on the same day. He works really quickly!

     

    It takes longer for the packages to arrive at his place than actual repair time.

  20. Posted

    Thanks for the info sm3.

    I'm fearful of removing the hot chip because the traces are so damn tiny. Wish I could find somebody who repairs c64's here in Phoenix. If I place a good ram on top of the hot one it might give an indication of the issue?

     

    That guy I linked above, he lives in the state of Washington. I've sent items for repair to him and I've also purchased items from him (power supplies). He doesn't charge all that much (for repairs) and is someone you can trust.

     

    You might want to just email him and ask your tech questions directly.

  21. Posted

    Hello All,

    First post to this part of Atariage because I am a TI'99er first and foremost.

    However, I enjoy all vintage computers/gaming machines and have 2 C64 computers.

    One is an SX64 and works just fine. The other is a 64C and does not - black screen.

     

    I have plugged in a kickman cartridge and get the screen attached here.

     

    attachicon.gifc64c.jpg

     

    I have opened the computer up and I reseated the chips - no change.

    I did a touch test and found u10 and u22 (ram) too hot to touch - replaced the ram chip in u10 (socketed) and could not in u22(not socketed)

    Somebody must have been in the computer before, right?

    Anyway, Do you think replacing the hot u22 ram will fix the issue and get the computer to work properly?

    Thanks for any tips you might be able to give me.

    -Ralph...

     

    Hi, there are many causes for a blank screen on the Commodore 64. It's possible that bad RAM is your issue, but it could be something else as well. The Kickman cartridge is what's called an "Ultimax" cartridge. These can sometimes give you an indication of a failure because they bypass certain components like RAM and ROMs.

     

    Some people have luck testing for failing RAM by putting a known good chip on top of the old. But a good indication of a failed RAM is it becoming really hot like you've stated.

     

    I would also check your power supply. If you are using an original "brick" type of power supply, I'd get rid of it as soon as I could and find a modern replacement. They are the cause of a lot of failures in the Commodore 64.

     

    Check out this link of a former service tech for Commodore: http://personalpages.tds.net/~rcarlsen/cbm/c64/

     

    Lots of good information there to help you troubleshoot the issue yourself. He also still does repairs as well.

    • Like 1

  22. Posted

    I suppose you could say LS-DOS (or LDOS) is closer to a "standard" DOS than most since it was essentially the same as TRSDOS 6 (Tandy hired Logical Systems to create TRSDOS 6).

     

    LDOS evolved from code (VTOS) that was written by the original TRSDOS programmer for the Model 1, Randy Cook.

     

    One of the benefits of using LDOS on the Model I & III is that Model III LDOS can read disks from Model I LDOS. Something that can't be done with the original TRSDOS versions.

     

    This is one of those areas (just like the Atari world) where there are many different preferences.

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