Changes between Version 13 and Version 14 of TeradriveHardwareNotes


Ignore:
Timestamp:
09/01/2024 08:55:28 PM (5 weeks ago)
Author:
Mike Pavone
Comment:

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  • TeradriveHardwareNotes

    v13 v14  
    7777      bit 2: Controls video switch - 0 = PC video, 1 = MD video\\
    7878      bit 3: Dual boot bit. When both this and bit 1 are set, bit 0 is ignored and both CPUs run independently.\\
    79       bit 4: Unclear function. When set bits 4 & 5 become 10 in AE0003 and 1165 returns a fixed sequence (D5,7F,00,AA,55,FF,80,2A)\\
     79      bit 4: Unclear function. When set bits 4 & 5 become 10 in AE0003 and 1165 returns a stream of bytes.\\
     80             Unclear circumstances will cause this to shift to a fixed sequence (D5,7F,00,AA,55,FF,80,2A) that\\
     81             only updates on writes to the PC IO region (AFXXXX)\\
     82             Setting this bit in "dual boot" mode tends to lead to 68K lockups\\
    8083      bit 5: Unknown\\
    8184      bit 6: Set on TMSS failure immediately before wedging 68K by reading from VDP while configured for writes\\
    8285      bit 7: Seems to start as 1, clearable on 68K but not on 286\\
    8386      Dual boot mode makes all Teradrive hardware except AE000X and A14000 inaccessible (no !DTACK)
     87      Switching between 68K exclusive and dual boot mode does NOT reset the 68K like switches to 286 exclusive mode
    84881165: `0000RR0R`
    8589      bit 0: Indicates PC/MD switch setting, 0 = MD boot, 1 = PC boot\\