===========#==#=======#===============================================#=====
----------------------|DMA, WD1772 Disk Controller |-----
===========#==#=======#===============================================#=====
$FFFF8604.W|RW|WDC_SEC|FDC/HDC Access/Sector Count |
$FFFF8606.W|R-|WDC_DMA|DMA Status %________ _____DSE |
| | | Data request condition--------------------+|| |
| | | Sector count 0:zero,1:not zero-------------+| |
| | | DMA 0:error,1:no error----------------------+ |
| | | CORRECTED 2026: bit 0 was listed inverted. The|
| | | bit is CLEAR on error and SET when there is no|
| | | error. Per Atari TOS bios/floppy.S and EmuTOS |
| | | bios/dma.h, confirmed by ijor. |
|-W| |DMA Mode %_______W FD_SHAA_ |
| | | 0:read,1:write---------------------+ || |||| |
| | | 0:HDC,1:FDC access-------------------+| |||| |
| | | DMA 0:on,1:off------------------------+ |||| |
| | | 0:FDC/HDC register 1:sector count-------+||| |
| | | 0:FDC,1:HDC access-----------------------+|| |
| | | A1/A0 pin 0:low,1:high--------------------++ |
| | | NOTE: bit 6 is nominally DMA enable/disable |
| | | but is ignored on STF and STE, so $90 behaves |
| | | the same as $D0. |
$FFFF8609.B|RW|WDC_BSH|DMA Base and Counter Hi |
$FFFF860B.B|RW|WDC_BSM|DMA Base and Counter Mi |
$FFFF860D.B|RW|WDC_BSL|DMA Base and Counter Lo |
$FFFF860E.B|RW|WDC_FDN|Frequency and Density control %______FD |STE,F
| | |Frequency 0:8MHz,1:16MHz--------------------+| |
| | |Density 0:DD,1:HD----------------------------+ |
| | | CORRECTED 2026: was labelled WDC_BSL, |
| | | duplicating $FFFF860D. Renamed WDC_FDN. |
===========#==#=======#===============================================#=====
----------------------|DMA SCSI |-----
===========#==#=======#===============================================#=====
$FFFF8701.B|RW|SCS_DA0|DMA Address Pointer (Highest byte) |TT
$FFFF8703.B|RW|SCS_DA1|DMA Address Pointer (High byte) |TT
$FFFF8705.B|RW|SCS_DA2|DMA Address Pointer (Low byte) |TT
$FFFF8707.B|RW|SCS_DA3|DMA Address Pointer (Lowest byte) |TT
$FFFF8709.B|RW|SCS_BC0|DMA Byte Counter (Highest byte) |TT
$FFFF870B.B|RW|SCS_BC1|DMA Byte Counter (High byte) |TT
$FFFF870D.B|RW|SCS_BC2|DMA Byte Counter (Low byte) |TT
$FFFF870F.B|RW|SCS_BC3|DMA Byte Counter (Lowest byte) |TT
$FFFF8710.W|Rw|SCS_DA0|Rest data (High Word) |TT
$FFFF8712.W|Rw|SCS_DA0|Rest data (Low Word) |TT
| | | CHECK: both Rest data registers carry the |
| | | label SCS_DA0, which also duplicates the DMA |
| | | Address Pointer label above. Needs distinct |
| | | labels. |
$FFFF8714.W|Rw|SCS_CTL|DMA SCSI Control Register %________ BZ____DW |TT
| | | Bus Error 0:no,1:yes-----------------+| || |TT
| | | Byte Counter Zero 0:no,1:yes----------+ || |TT
| | | DMA 0:off,1:on-----------------------------+| |TT
| | | DMA 0:read,1:write--------------------------+ |TT
===========#==#=======#===============================================#=====
----------------------|5380 SCSI Drive Controller |-----
===========#==#=======#===============================================#=====
$FFFF8781.B|RW|SCS_CDB|Contents of SCSI-Data Buses |TT
$FFFF8783.B|RW|SCS_ICR|Init Command Register |TT
$FFFF8785.B|RW|SCS_TSR|Transfer Start Register |TT
$FFFF8787.B|RW|SCS_TCR|Target Command Register |TT
$FFFF8789.B|RW|SCS_BSR|Bus Status Register |TT
$FFFF878B.B|RW|SCS_DSR|Device Status Register |TT
$FFFF878D.B|RW|SCS_BCD|SCSI-Bus Command Data |TT
$FFFF878F.B|RW|SCS_RES|Reset Interrupts,Parity error,Start DMA-Action |TT
Back to Memory Map for Atari ST,STE,TT and Falcon