Memory Map
The following is the memory map for the Atom. Shaded areas indicate those present on the minimal system.
| Hex Address | Contents | Annotations |
|---|---|---|
| 0000 | Block Zero RAM | 1KB RAM |
| 0400 | Teletext VDG RAM | |
| 0800 | VDG CRT Controller | |
| 0900 | ||
| 0A00 | Optional FDC | |
| 0A80 | ||
| 1000 | Peripherals space | |
| 2000 | Catalogue buffer | |
| 2200 | Sequential File buffers | |
| 2800 | Floating point variables | Internal RAM 5KB max. |
| 2900 | Extension Text space RAM | |
| 3C00 | Off-board Extension RAM | |
| 8000 | 8000-01FF for mode 0 (512 bytes text) | Video and BASIC RAM 6KB max. |
| 8000 | 8000-83FF for mode 1 (1 KB graphics) | |
| 8000 | 8000-85FF for mode 2 (1.5 KB graphics) | |
| 8000 | 8000-8BFF for mode 3 (3 KB graphics) | |
| 8000 | 8000-97FF for mode 4 (6 KB graphics) | |
| 9800 | ||
| A000 | Optional Utility ROM | |
| B000 | PPIA I/O Device | |
| B800 | Optional VIA I/O Device for Printer Interface | |
| C000 | ATOM BASIC Interpreter | 4KB ROM |
| D000 | Optional Extension ROM | |
| E000 | Optional Disk Operating System | |
| F000 | Assembler | 4 KB ROM |
| Cassette Operating System |
Read more about this topic: Acorn Atom
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