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IBM PC AT 5170 BIOS versions

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    #31
    Thank you Stone. Next is the conundrum of running it. The machine only has 2 5.25" floppies (probably high density). I have 2 of these and neither look like they've ever been used before, with a cut out in front of the case for a Syquest or Iomega removable drive.

    Since this is a BIOS sticky, would it be most appropriate to open up a new thread if I wanted to post pictures?
    IBM Computers: 5150 (16-64K, 64-256K), 5160, 5161, 5162, 5170 (regular and Tempest), Option 370 16 bit, PC Convertible
    PS/2 Machines: 30, 40SX, 50Z, 55SX, 60, 70, 77 (Lacuna & Bermuda), 80, 85, 90 XP, 95, "E"
    Vintage ThinkPads: 300, 360C/CE, 510CS, 560/E, 600E/X, 701C/CS, 700, 720C, 730TE (tablet), 750C/P (color and tablet models), 755C/CE/CD/CDV/CX, 760ED, 765L, 770
    Vintage UNIX workstations: 2/120, 3/75, 3/60, SS 2/5/20, U2 Ent, HP 715/100, several RS/6000s

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      #32
      I found another EPROM chip with P/N for IBM PC 5170 (Type 1) on eBay.

      U17 -- P/N : 6448894
      U27 -- P/N : 6480084
      U37 -- P/N : 6448895
      U47 -- P/N : 6480085

      https://i.ebayimg.com/images/g/eCUAA...fT/s-l1600.jpg
      https://www.ebay.com/itm/224368049783

      I'm sure this is for BIOS Rev.2 (06/10/85) for Type 2 motherboard normally.
      But this is already adapted on Type 1 motherboard.IBM5170V2-1.jpg

      Comment


        #33
        Some people debate between keeping things as original as possible and doing modifications; case in point replacing the BIOS on the 5170's due to hardware warnings and incompatibility with new drives. Personally, I think there has to be a balance. To that point, wanted to share a series of videos on Adrian's Digital Basement on YouTube covering the 5170, and specifically modifications to the IBM 5170 BIOS that "fixes" a couple of items. Like many people, he was trying to find a balance between trying to use the original IBM BIOS, or switching to another BIOS (QuadTel) to allow it to use other cards and work with large files.

        Here is the BIOS specific video, but the entire 5170 is a good watch:

        https://www.youtube.com/watch?v=qO3xrl0XR-4

        Also has a video on his second channel about "extreme overclocking" on a 5170:

        https://www.youtube.com/watch?v=81ezGc1Eb1M

        Also if you want, a video on an MFM emulator that would allow you to use the original IBM MFM controller, which wouldn't need any BIOS mods.

        https://www.youtube.com/watch?v=q__R8khTwo8

        But just wanted to share the results of Adrian's work, since he used a lot of information from MinusZeroDegrees, so wanted to share with the community.

        Comment


          #34
          Originally posted by TechElucidation View Post
          Some people debate between keeping things as original as possible and doing modifications; case in point replacing the BIOS on the 5170's due to hardware warnings and incompatibility with new drives. Personally, I think there has to be a balance. To that point, wanted to share a series of videos on Adrian's Digital Basement on YouTube covering the 5170, and specifically modifications to the IBM 5170 BIOS that "fixes" a couple of items. Like many people, he was trying to find a balance between trying to use the original IBM BIOS, or switching to another BIOS (QuadTel) to allow it to use other cards and work with large files.

          Here is the BIOS specific video, but the entire 5170 is a good watch:

          https://www.youtube.com/watch?v=qO3xrl0XR-4

          Also has a video on his second channel about "extreme overclocking" on a 5170:

          https://www.youtube.com/watch?v=81ezGc1Eb1M

          Also if you want, a video on an MFM emulator that would allow you to use the original IBM MFM controller, which wouldn't need any BIOS mods.

          https://www.youtube.com/watch?v=q__R8khTwo8

          But just wanted to share the results of Adrian's work, since he used a lot of information from MinusZeroDegrees, so wanted to share with the community.
          I am very much not a fan of the first two BIOS "fixes" described in that video. The first one is simply a kludge to ignore what could potentially be a legitimate configuration error by not testing that the FDD matches the configuration.

          The second one is a bit more nuanced but it was done wrong:
          Code:
          J_OK:
          MOV DX,03F1H ; D/S/P DIAGNOSTIC REGISTER
          IN AL,DX ; READ D/S/P TYPE CODE
          AND AL,11111000B ; KEEP ONLY UNIQUE CODE FOR D/S/P
          CMP AL,01010000B ; D/S/P CARD - MULTIPLE DATA RATE?
          JZ J_OK3 ; IF SO JUMP
          
          MOV DX,05F7H ; FIXED DISK DIAGNOSTIC REGISTER
          IN AL,DX ; READ FIXED DISK TYPE CODE
          AND AL,11110000B ; KEEP ONLY UNIQUE CODE FOR F/D
          CMP AL,10100000B ; FIXED DISK ADAPTER ?
          JZ J_FAIL ; MUST BE COMBO ELSE ERROR
          
          MOV BL,0FH ; OUTER LOOP COUNT WAIT FOR BUSY OFF
          SUB CX,CX
          MOV DX,01F7H ; HARD FILE STATUS PORT
          J_OK1:
          IN AL,DX ; GET THE STATUS
          TEST AL,080H ; IS THE CONTROLLER BUSY?
          JZ J_OK2 ; CONTINUE IF NOT
          LOOP J_OK1 ; TRY AGAIN
          DEC BL ; DECREMENT OUTER LOOP
          JNZ J_OK1 ; TRY AGAIN IF NOT ZERO
          AND AL,0CH ; BITS 2 & 3 = 0 IF MULTI DATA CAPABLE
          JZ J_OK3 ; GO IF YES
          JMP SHORT J_FAIL ; NO MULTIPLE DATA RATE CAPABILITY
          J_OK2:
          MOV DX,1F4H ; VERIFY MULTIPLE DATA RATE CAPABLE
          MOV AL,055H ; WRITE TO THE CYLINDER BYTE
          OUT DX,AL
          JMP $+2 ; I/O DELAY
          IN AL,DX ; CHECK DATA WRITTEN = DATA READ
          CMP AL,055H
          JNZ J_FAIL ; GO IF NOT
          MOV AL,0AAH ; WRITE ANOTHER PATTERN
          OUT DX,AL
          JMP $+2 ; I/O DELAY
          IN AL,DX
          CMP AL,0AAH ; IS DATA PATTERN THE SAME?
          JZ J_OK3 ; GO IF SO
          Here is the relevant section of the floppy test code. What the person did is change the first JZ up there to a unconditional jump to essentially skip testing the controller for 500k data rate. What they were actually trying to achieve (preventing the 601 from being thrown when using a different FDC than the stock combo card) could have been achieved by NOPing the "JZ J_FAIL ; MUST BE COMBO ELSE ERROR" after where it tests port 5F7. This is the check that non-IBM combo cards will fail, and incidentally Adrian's IBM combo card failed it because it was *actually broken* and he just ignored this fact lol

          Comment


            #35
            Originally posted by maxtherabbit View Post

            I am very much not a fan of the first two BIOS "fixes" described in that video. The first one is simply a kludge to ignore what could potentially be a legitimate configuration error by not testing that the FDD matches the configuration.

            The second one is a bit more nuanced but it was done wrong:
            Code:
            J_OK:
            MOV DX,03F1H ; D/S/P DIAGNOSTIC REGISTER
            IN AL,DX ; READ D/S/P TYPE CODE
            AND AL,11111000B ; KEEP ONLY UNIQUE CODE FOR D/S/P
            CMP AL,01010000B ; D/S/P CARD - MULTIPLE DATA RATE?
            JZ J_OK3 ; IF SO JUMP
            
            MOV DX,05F7H ; FIXED DISK DIAGNOSTIC REGISTER
            IN AL,DX ; READ FIXED DISK TYPE CODE
            AND AL,11110000B ; KEEP ONLY UNIQUE CODE FOR F/D
            CMP AL,10100000B ; FIXED DISK ADAPTER ?
            JZ J_FAIL ; MUST BE COMBO ELSE ERROR
            
            MOV BL,0FH ; OUTER LOOP COUNT WAIT FOR BUSY OFF
            SUB CX,CX
            MOV DX,01F7H ; HARD FILE STATUS PORT
            J_OK1:
            IN AL,DX ; GET THE STATUS
            TEST AL,080H ; IS THE CONTROLLER BUSY?
            JZ J_OK2 ; CONTINUE IF NOT
            LOOP J_OK1 ; TRY AGAIN
            DEC BL ; DECREMENT OUTER LOOP
            JNZ J_OK1 ; TRY AGAIN IF NOT ZERO
            AND AL,0CH ; BITS 2 & 3 = 0 IF MULTI DATA CAPABLE
            JZ J_OK3 ; GO IF YES
            JMP SHORT J_FAIL ; NO MULTIPLE DATA RATE CAPABILITY
            J_OK2:
            MOV DX,1F4H ; VERIFY MULTIPLE DATA RATE CAPABLE
            MOV AL,055H ; WRITE TO THE CYLINDER BYTE
            OUT DX,AL
            JMP $+2 ; I/O DELAY
            IN AL,DX ; CHECK DATA WRITTEN = DATA READ
            CMP AL,055H
            JNZ J_FAIL ; GO IF NOT
            MOV AL,0AAH ; WRITE ANOTHER PATTERN
            OUT DX,AL
            JMP $+2 ; I/O DELAY
            IN AL,DX
            CMP AL,0AAH ; IS DATA PATTERN THE SAME?
            JZ J_OK3 ; GO IF SO
            Here is the relevant section of the floppy test code. What the person did is change the first JZ up there to a unconditional jump to essentially skip testing the controller for 500k data rate. What they were actually trying to achieve (preventing the 601 from being thrown when using a different FDC than the stock combo card) could have been achieved by NOPing the "JZ J_FAIL ; MUST BE COMBO ELSE ERROR" after where it tests port 5F7. This is the check that non-IBM combo cards will fail, and incidentally Adrian's IBM combo card failed it because it was *actually broken* and he just ignored this fact lol
            Nice avatar Max.

            Surely not everyone was Kung-Fu fighting

            Comment

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