Changes between Version 6 and Version 7 of TeradriveHardwareNotes

Timestamp:

08/04/2024 07:29:02 AM (9 months ago)

Author:

Mike Pavone

Comment:

--

TeradriveHardwareNotes

@@ -34 +34 @@
 `A13000 - A130FF`: !TIME (cart mapper registers, also `MARS` at A130EC when a 32X is attached)\\
 `A13100 - A13FFF`: unmapped (!DTACK not asserted, will freeze without additional hardware)\\
-`A14000 - A14???`: TMSS lock (note this functions differently from the standard TMSS lock register)\\
+`A14000 - A14003`: TMSS lock, write only (note this functions differently from the standard TMSS lock register)\\
+`A14004 - A150FF`: unmapped (!DTACK not asserted, will freeze without additional hardware)\\
 `A15100 - A153FF`: normally unmapped (no !DTACK), 32X registers if 32X present\\
 `A15400 - ADFFFF`: unmapped (!DTACK not asserted, will freeze without additional hardware)\\
@@ -91 +92 @@
       when taken together with 1166, holds `68K address >> 12`\\
       Also used along with 1166 for passing params from PC side to MD-side firmware\\
+
+== MD Side Bus Switch Registers ==
+
+Note: The 68K can also access the PC-side registers via the AFXXXX region which gives access to PC IO space unless the Teradrive is in dual boot mode. This section only lists registers that are directly accessible by the 68K.
+
+`A14000`: TMSS unlock, write-only.\\
+          Seems to treat all writes as word-wide so byte-writes can't be used to unlock.\\
+          Writing `SEGA` here unlocks PC access to MD hardware via the bus switch\\
+
+`AE0001`: `XXXXRRXX`\\
+          bit 0: Value written here is readable at 1163 bit 4\\
+          bit 1: Value written here is readable at 1163 bit 5\\
+          bit 2: Returns value written to 1163 bit 6\\
+          bit 3: Returns value written to 1163 bit 7\\
+          bit 4: Appears to be used by TMSS firmware to detect cold boot (0 = cold boot, 1 = warm reset)\\
+          bit 7: Maps PC side memory at $0 when set as long as AF1164 bit 1 is clear\\
+
+`AE0003`: `XXXXXXXX`\\
+          Selects 1 MiB bank of 286 address space visible at $B00000\\
+          
 
 == IC List