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Type: Posts; User: chris_nh

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  1. Replies
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    What is written on the ROM(?) chip next to the...

    What is written on the ROM(?) chip next to the 8085?? Anything on the back of the board?
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    I'm going to guess maybe a network card, or...

    I'm going to guess maybe a network card, or perhaps a terminal interface card for a mainframe system ... is the connector db9? male or female?
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    Wow, nice find, very low serial # ... where was...

    Wow, nice find, very low serial # ... where was this one hiding?
  4. Hi Ruud, did you receive my message about the bug...

    Hi Ruud, did you receive my message about the bug fix in dochecksum routine?
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    Cool build! What is the checkit benchmark for...

    Cool build! What is the checkit benchmark for that combo with the v20?
  6. Replies
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    Should be fine ... I think the spec for TTL...

    Should be fine ... I think the spec for TTL logic is 2.7-5v for logic 1 and CMOS is 3.5v-5v for logic 1. I think the 5v spec is also +- .25v, so 4.75v should be completely acceptable.
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    Have you checked sw1:7/8 for continuity? Test...

    Have you checked sw1:7/8 for continuity? Test with meter on underside of board to see if switch contacts are actually contacting. I have a board with this problem on sw1:5, and it does not make...
  8. Thanks for the pointers! I think I'll give A86 a...

    Thanks for the pointers! I think I'll give A86 a try as well.
  9. I have found the documentation I need for this...

    I have found the documentation I need for this version of MASM, including proper program structure examples.
  10. Replies
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    2,252

    IBM basic roms on 5150 board ... I tried 2...

    IBM basic roms on 5150 board ... I tried 2 different ROM sets on 2 different boards. Landmark passes the checksums, but yours fails the checksums. I am hoping to get an ASM compiler working (per my...
  11. Thanks ... I will give NASM a try for sure, but I...

    Thanks ... I will give NASM a try for sure, but I do want to have a development path for working directly on the 8088 hardware. If I'm just fiddling around, it doesn't make sense to cross compile...
  12. Seeking orientation for x86 assembly on PC

    SO ...

    I'm a developer in the modern computing realm by profession, but mostly work with higher level languages. I'm looking to learn assembly on the 8088/PC machine, but I'm having a hard time...
  13. Lots of opinions out there on lubricating...

    Lots of opinions out there on lubricating steppers, but I use regular 3-in-1 oil and put a drop around the end of the shaft on the back and/or front of the stepper motor, depending on the type of...
  14. Have you tried a fresh low level format on the...

    Have you tried a fresh low level format on the drive? Also, I would recommend lubricating the head stepper motor if it has not been done ever.
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    The computer is working ... you might just need...

    The computer is working ... you might just need to clean the floppy drive. Also, are you sure the boot disk is any good?
  16. Replies
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    HI Ruud, I'm not 100% sure there is a bug, I...

    HI Ruud,

    I'm not 100% sure there is a bug, I only arrived at that conclusion because I've tried the rom on several boards and it always fails the checksums. I looked at your code and it looks...
  17. Replies
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    Looks like a neat find - would love to see some...

    Looks like a neat find - would love to see some pics of the motherboard after you open it up. Does it boot?
  18. Replies
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    2,252

    I want to just give a quick review of the...

    I want to just give a quick review of the problems discovered on this board, just if anyone would find it useful:

    The board: 16-64k early revision 5150 motherboard presenting as "dead board" with...
  19. Replies
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    OK, FOUND IT! Finally Keyboard socket on the...

    OK, FOUND IT! Finally

    Keyboard socket on the motherboard, pin 1 is physically missing, so there it is. I guess I need to find a socket
  20. Replies
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    haha sorry, I meant modem7 I discovered the...

    haha sorry, I meant modem7

    I discovered the speaker noise was due to power supply, and my other bench supply also decided it would be a good time to stop working, but I found another working...
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    Stone, you were right ... I hadn't noticed, but...

    Stone, you were right ... I hadn't noticed, but somewhere throughout all the handling of this board, sw3 had become switched ON, which of course was the cause of the ram issue. With SW3&4 OFF I'm...
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    Switch 3 and 4 are indeed off because this board...

    Switch 3 and 4 are indeed off because this board is fitted with 64k of RAM. The number I'm expecting to see for this board/bios combo is 61404.

    The 12k number is what appears when SW2:1-5 are ON....
  23. Replies
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    Well, finally the board boots to cassette basic,...

    Well, finally the board boots to cassette basic, but only with the keyboard unplugged. Cassette Basic is also reporting 12252 bytes free instead of 16k ... but all good clues. RAM chips are all...
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    OK ... I've made some more progress in...

    OK ... I've made some more progress in troubleshooting.

    I'm quite positive there is no problem with the ROM chips. I'm fairly certain Ruud's diagnostic has a bug in the ROM checksum test.
    ...
  25. Replies
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    (I couldn't edit the post above? Perhaps there...

    (I couldn't edit the post above? Perhaps there is a time limit on edits ...)

    Just to add clarity to point 2b above, Ruud's diagnostic fails with ROMS inserted
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