• IBM MCA SCSI Console probulation!

    From Louis Ohland@21:1/5 to All on Sun Apr 16 19:15:24 2023
    MAJ Tom skipped off the upper atmosphere [too shallow of an angle] but
    he managed to get off a cryptic message...

    History: a few years back, I got the idea from somewhere [Evil Dave?
    WBST?] that there was a console in the IBM MCA SCSI firmware. MAJ Tom
    was trying to mollify me by pretending he was going to look into it...

    There are three versions, my SWAG is all have roughly the same layout
    and registers. The versions are ver 1.x 80C32 based, ver 2.x 80C188
    based, and ver 3.x 80C186 based.

    Fzzt! Crackle! Bzzt! -------->

    Ok I have located the console code and figured out how it uses the
    various strings. Here is a more accurate description of the commands
    supported in version 3.1:

    Single-character DEBUG-like Commands: (https://montcs.bloomu.edu/Information/LowLevel/DOS-Debug.html)

    B - Dump memory (B [address]; address = offset | segment:offset)
    D - Dump memory (D [address]; address = offset | segment:offset)
    E - Enter to memory (E address; address = offset | segment:offset) [input]
    F - Fill memory [input > segment_word offset_word count_word
    pattern_byte (0: FF, 1: 00, 2: AA55, 3: FF00)]
    G - ? ("Go" in DOS DEBUG) [terminates?]
    T - ? ("Trace" in DOS DEBUG) [terminates?]
    I - Input (I port)
    O - Output (O port byte)
    Q - Quit [terminates]
    R - Register(s); (R [reg_name]) sets value of the specified reg. or
    displays value of all x86 regs+flags [input*]

    Proprietary Commands:

    @ - ?

    PSCB - Set SCB channel registers? [input]
    RSCB - Display SCB channel registers
    RESET
    REV - Print uCode, Malibu & Cutlass revisions
    RLTB - Display LTB channel registers
    STAT - Prints ISR ESRI ESRII status (?)
    FI - Failure info - prints Failure ID & Test Number
    LED - Diag. LED control? [input > 0: LED OFF, !=0: LED ON?]

    Notes:
    [input] - the command requires additional input from the user
    [terminates] - the command terminates the console environment

    Now the elephant in the room... how to enter and interact with the
    console? I'm still not quite sure.

    It uses B000:4Ah for input and output and the I/O is serial. So,
    possibly the J7 header? TX/RX may be all that is needed.

    The console may not be accessible by default. It activates on hw int. 1
    - single step and hw int. 2 - breakpoint instruction. There are also 3
    calls to it in the main microcode loop - something that is rather hard
    to decode (nested jump loops, unknown memory locations everywhere...).

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  • From Tomas Slavotinek@21:1/5 to All on Thu May 18 00:31:00 2023
    More info here:
    https://ardent-tool.com/IBM_SCSI/Serial_Console.html

    Success with Tribble, no luck with the other adapters yet...

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