Janus AT Memory Map

AMIGA ACCESS: Amiga Interface Offset Address = Base Addr.

  • Base Addr. + (00000 - 1FFFF) : Byte Access
  • Base Addr. + (20000 - 3FFFF) : Word Access
  • Base Addr. + (40000 - 5FFFF) : Graphic Access
  • Base Addr. + (60000 - 7FFFF) : I/O Register Access

INTERFACE MEMORY MAP:

Interface Offset Address Size Usage
00000-0FFFF 64K DISK BUFFER RAM
10000-17FFF 32K COLOR VIDEO RAM
18000-1BFFF 16K PARAMETER RAM
1C000-1DFFF 8K MONO VIDEO RAM
1E000-1FFFF 8K I0-PAGE

Kinds of memory access on the following pages:

  • B = Byte access
  • G = Graphic access
  • W = Word access

(*) selectable by BIT 5 and 6 of the MODE REGISTER

  • BIT 5 = SEL1
  • BIT 6 = SEL2

 

A2286/A2386 Memory Map PC Side

PC Address Range Size Usage kind
of access		 Amiga Interface
Offset Address
0000-03FF 1K IO-PAGE B 1E000-1FFFF
      W 3E000-3FFFF
      G 5E000-5FFFF
        7E000-7FFFF
A0000-AFFFF 64K DISK BUFFER RAM (*) B 00000-0FFFF
    (*) W 20000-2FFFF
    (*) G 40000-4FFFF
B0000-B1FFF 8K MONO VIDEO RAM B 1C000-1DFFF
      W 3C000-3DFFF
      G 5C000-5DFFF
B8000-BFFFF 32K COLOR VIDEO RAM B 10000-17FFF
      W 30000-37FFF
      G 50000-57FFF
D0000-D3FFF 16K PARAMETER RAM B 18000-1BFFF
      W 38000-3BFFF
      G 58000-5BFFF
D4000-DFFFF 64K DISK BUFFER RAM (*) B 04000-0FFFF
    (*) W 24000-2FFFF
    (*) G 44000-4FFFF

A2286/A2386 Memory Map Amiga Side

Amiga Interface
Offset Address		 AT Address Range Size Usage kind of
access
00000-0FFFF A0000-AFFFF 64K DISK BUFFER RAM (*) B
00000-03FFF CAN NOT BE ACCESSED BY THE AT
04000-0FFFF D4000-DFFFF 48K DISK BUFFER RAM (*) B
10000-17FFF B8000-BFFFF 32K COLOR VIDEO RAM B
18000-1BFFF D0000-D3FFF 16K PARAMETER RAM B
1C000-1DFFF B0000-B1FFF 8K MONO VIDEO RAM B
1E000-1FFFF 0000-03FF 1K I0-PAGE B
20000-2FFFF A0000-AFFFF 64K DISK BUFFER RAM (*) W
20000-23FFF CAN NOT BE ACCESSED BY THE AT
24000-2FFFF D4000-DFFFF 48K DISK BUFFER RAM (*) W
30000-37FFF B8000-BFFFF 32K COLOR VIDEO RAM W
38000-3BFFF D0000-D3FFF 16K PARAMETER RAM W
3C000-3DFFF B0000-B1FFF 8K MONO VIDEO RAM W
3E000-3FFFF 0000-03FF 1K I0-PAGE W
40000-4FFFF A0000-AFFFF 64K DISK BUFFER RAM (*) G
40000-43FFF CAN NOT BE ACCESSED BY THE AT
44000-4FFFF D4000-DFFFF 48K DISK BUFFER (*) G
50000-57FFF B8000-BFFFF 32K COLOR VIDEO RAM G
58000-5BFFF D0000-D3FFF 16K PARAMETER RAM G
5C000-5DFFF B0000-B1FFF 8K MONO VIDEO RAM G
5E000-5FFFF 0000-03FF 1K I0-PAGE G
7E000-7FFFF 0000-03FF 1K I0-PAGE W

Last Update: 14.08.2023