Memory Map




This is the text form of the Memory Map for this system. It will probably change in time, but it is a starting point for the design of V1.0.

As this is a 65xxx based system, RAM, ROM, I/O, etc. are all memory mapped, which means that there are "holes" in memory to access different areas or functions within the system.

As with everything else on this site, there is a "Base" area, in this case the direct page, and then everything else. In this system, the base has the majority of hardware in it - this allows for easier address decoding in the beginning during my development (ie: I am just working on direct page hardware and code right now, once that is complete and working "normally" I will start working with memory above the base 64K).

Memory addresses on this system go from $000000 - $FFFFFF. The direct page is located at $0000 - $FFFF.


$FE0000 - $FFFFFF Large expansion slot - 128K bytes allocated,Intended for a graphic card or other hardware that requires a large address space.

$FDFC00 - $FDFFFF Medium expansion slot - 1024 bytes allocated, general purpose slot.

$DF0000 - $FDFBFF Battery Backed up RAM storage - 1.98Meg storage space for programs, data and such

$DB0000 - $DEFFFF Upper EPROM space - 256K for extended drivers, data, misc. operational software

$010000 - $DAFFFF Upper RAM - ~13.95Meg upper RAM area, can be re-allocated, or used as RAM

$00E000 - $00FFFF Base Eprom - ~8K base eprom containing monitor app, keyboard, RS232, base LCD, main LCD RTC drivers, as well as boot code

$00DE00 - $00DFFF Expansion slot: 512 bytes allocated, GP slot

$00DDF0 - $00DDFF Interrupt detection hardware

$00DDE0 - $00DDEF Base LCD controlled thru 6522 via

$00DDD0 - $00DDDF Keyboard / RTC thru 6522 via

$00DDC0 - $00DDCF RS232 ports thru 6522 via, 2-4 RS232 ports

$00DDB0 - $00DDBF Main LCD display thru 6522 via

$00DDA0 - $00DDAF Expansion slot thru Via

$00DD90 - $00DD9F Expansion slot thru Via

$00DD80 - $00DD8F Expansion slot thru via

$00DD70 - $00DD7F Expansion slot thru via

$00DD60 - $00DD6F Expansion slot thru via

$00DD50 - $00DD5F Expansion slot thru via

$008000 - $00D4FF 32K RAM module 2, ~21.25K not allocated for I/O, upper ~1200 bytes reserved for driver buffers, display area, etc.

$000000 - $007FFF 32K RAM module 1, bottom 512 bytes ($0000 - $01FF) reserved, stack and old 0 page.