forked from amberisvibin/chibi-pc09
56 lines
1.6 KiB
Markdown
56 lines
1.6 KiB
Markdown
# CHIBI PC-09 Technical Specification
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5-17-21 Amber Zeller
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## Quick Specs
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#### CPU
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1, 1.5, 2 MHz Motorola 6809
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#### Memory
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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.
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#### I/O
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2k block, position 30. Addresses EFFF-F7FE. Further subdivided into 128 devices of 16 addresses each.
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## Address Space Diagram
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| Address Range | Description |
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| ------------- | ---------------------- |
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| 0000 - 07FF | Kernal Root Block |
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| 0800 - EFFE | Standard Memory Blocks |
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| EFFF - F7FE | I/O Block |
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| F7FF - FFFF | Vector Block |
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## I/O Block Description
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11 bits per block
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128 devices are possible, though will likely never be used.
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| Bits | Description |
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| ---- | ----------------- |
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| 0-6 | Device selection |
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| 7-10 | Address selection |
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## Expansion Card Description
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Byte 0 of every card should contain a descriptor. The structure of the descriptor is described in the following table.
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| Bits | Descriptor |
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| ---- | ---------- |
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| 0-2 | Type |
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### Type Descriptor Table
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| Type Descriptor | Description | Example |
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| --------------- | ------------------------------- | -------- |
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| 000 | Block Storage | SD Card |
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| 001 | ANSI I/O Stream | UART |
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| 010 | ANSI Compatible Graphics Device | VGA64 |
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| 011 | Input Device | Keyboard |
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| 1xx | Other | Other |
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