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Thread: 8087 on 8088 motherboard that have no socket for it

  1. #41
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    Well, here's an old thread where MCPDIAG fails on a Juko MB with V20 or 8088 installed.
    Last edited by Chuck(G); November 11th, 2019 at 11:10 PM.

  2. #42

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    great find thanks! Good to know my use case on Z171 isn't necessarily defective. The thought of disassembling MCPDIAG is unappealing. After reading that application note for 8087, it seems like the best option for dealing with the interrupt may be to leave it disconnected altogether.. since there is likely no facility to deal with MCP exceptions via software interrupt built into a machine that was never intended to support a math coprocessor. My current dual socket adapter is a hand made thing; not the cleanest implementation, and I notice some ringing on the datapath.. I may spin a small board to see if better signal quality, and possibly that is related to the strange MCPDIAG test results. Stab in the dark but a nice board is better anyhow.

    Next project-- convert the Z171 from 640kB of DRAM into 1MB of SRAM. Next Next project... increase clock from 4.77MHz to 9.54MHz.

    Side note. I notice that the Z171 displays the odd random character on the screen when using V20.

  3. #43

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    Quote Originally Posted by Twospruces View Post
    great find thanks! Good to know my use case on Z171 isn't necessarily defective. The thought of disassembling MCPDIAG is unappealing. After reading that application note for 8087, it seems like the best option for dealing with the interrupt may be to leave it disconnected altogether.. since there is likely no facility to deal with MCP exceptions via software interrupt built into a machine that was never intended to support a math coprocessor. My current dual socket adapter is a hand made thing; not the cleanest implementation, and I notice some ringing on the datapath.. I may spin a small board to see if better signal quality, and possibly that is related to the strange MCPDIAG test results. Stab in the dark but a nice board is better anyhow.

    Next project-- convert the Z171 from 640kB of DRAM into 1MB of SRAM. Next Next project... increase clock from 4.77MHz to 9.54MHz.

    Side note. I notice that the Z171 displays the odd random character on the screen when using V20.

    There are several versions of MCPDIAG. Some complain about "integrity test" on XT machines (8087) and do not on ATs (80287/387/487), some output the same error on AT machines and not on XTs. I can make some tests and upload here the one that works fine on XT machines if someone is interested. I like MCPDIAG because it loads the FPU for 5 minutes and it often discovers problems when FPU is overclocked/overheated. I don't like MCPDIAG because it is tightly "hardwired" by using vectors that only Intel and licensed by Intel FPUs produce and it simply does not run on NPUs designed by Intel's competitors that produce slightly different results but otherwise work perfectly.

  4. #44

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    Quote Originally Posted by george View Post
    There are several versions of MCPDIAG. Some complain about "integrity test" on XT machines (8087) and do not on ATs (80287/387/487), some output the same error on AT machines and not on XTs. I can make some tests and upload here the one that works fine on XT machines if someone is interested. I like MCPDIAG because it loads the FPU for 5 minutes and it often discovers problems when FPU is overclocked/overheated. I don't like MCPDIAG because it is tightly "hardwired" by using vectors that only Intel and licensed by Intel FPUs produce and it simply does not run on NPUs designed by Intel's competitors that produce slightly different results but otherwise work perfectly.
    George that would be awesome.
    Sounds like you know how to make MCPDIAG run interations; I didnt see anything that let me do that, but I saw an iteration count.
    Anyhow I would be very interested in getting a valid MCPDIAG for XT. I can test it and report back.

  5. #45

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    Hi, as requested here is a version that works fine on XT with me. MCPDIAG does its 5 min. iterations automatically when no error is detected upon its start.
    Attached Files Attached Files

  6. #46

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    awesome, I will try and report back. Thanks very much!

  7. #47

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    Quote Originally Posted by george View Post
    Hi, as requested here is a version that works fine on XT with me. MCPDIAG does its 5 min. iterations automatically when no error is detected upon its start.
    hey thanks for this! seems to run well. passed all tests, and looping for 5 min. nice to have the file here in the forum stored for future reference as well!

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