forked from amberisvibin/chibi-pc09
1.3 KiB
1.3 KiB
CHIBI PC-09 Technical Specification
5-17-21 Amber Zeller
Quick Specs
CPU
1, 1.5, 2 MHz Motorola 6809
Memory
64k SRAM on external card for optional MMU capability. Seperated into 2k blocks, numbered 0-31. Only 62k of memory is accessible, due to the I/O block.
I/O
2k block, position 30. Addresses EFFF-F7FE. Further subdivided into 128 devices of 16 addresses each.
Address Space Diagram
| Address Range | Description |
|---|---|
| 0000 - 07FF | First Kernel Block |
| 0800 - EFFE | Standard Memory Blocks |
| EFFF - F7FE | I/O Block |
| F7FF - FFFF | Reset Vectors |
I/O Block Description
11 bits per block
128 devices are possible, though will likely never be used.
| Bits | Description |
|---|---|
| 0-6 | Device selection |
| 7-10 | Address selection |
Expansion Card Description
Byte 0 of every card should contain a 'type' descriptor.
| Type Descriptor | Description | Example |
|---|---|---|
| 00 | Block Storage | SD Card |
| 01 | ANSI I/O Stream | UART |
| 02 | ANSI Compatible Graphics Device | VGA64 |