Graduate Software: Difference between revisions
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=== Structure of a utility ROM === | === Structure of a utility ROM === | ||
Each ROM is 16KB and has the following structure: | |||
{| | |||
|- | |||
| ''Offset (Hex)'' | |||
| ''Count'' | |||
| ''Description'' | |||
|- | |||
| &100 | |||
| 256 | |||
| Directory (note 1) | |||
|- | |||
| &200 | |||
| &3e00 | |||
| Data area for files. | |||
|} | |||
Each directory entry has the following structure: | |||
{| | |||
|- | |||
| ''Offset (Hex)'' | |||
| ''Count'' | |||
| ''Description'' | |||
|- | |||
| 0 | |||
| 8 | |||
| Filename (note 2) | |||
|- | |||
| 8 | |||
| 1 | |||
| ? (unknown &20) | |||
|- | |||
| 9 | |||
| 2 | |||
| address in ROM for start of data for file (note 3) | |||
|- | |||
| 11 | |||
| 2 | |||
| length in bytes of file | |||
|- | |||
| 14 | |||
| 2 | |||
| (unknown) &feff | |||
|} | |||
Notes: | |||
1. Up to 16 files can be defined. Each file takes 1 entry. Unused entries are filled with &FF. | |||
2. Filename is in upper case, 8 characters long, padded with spaces. '.COM' extension is assumed when accessed. | |||
3. ROM starts at &c000. Therefore &c200 is the start of the first file. | |||
[[Category:Operating System]][[Category:CP/M]] | [[Category:Operating System]][[Category:CP/M]] | ||
Revision as of 15:39, 28 April 2018
Graduate software provided a version of CP/M+ on ROM.
Additional 'utility' roms contained CP/M programs installed on a ROM.
Structure of a utility ROM
Each ROM is 16KB and has the following structure:
| Offset (Hex) | Count | Description |
| &100 | 256 | Directory (note 1) |
| &200 | &3e00 | Data area for files. |
Each directory entry has the following structure:
| Offset (Hex) | Count | Description |
| 0 | 8 | Filename (note 2) |
| 8 | 1 | ? (unknown &20) |
| 9 | 2 | address in ROM for start of data for file (note 3) |
| 11 | 2 | length in bytes of file |
| 14 | 2 | (unknown) &feff |
Notes: 1. Up to 16 files can be defined. Each file takes 1 entry. Unused entries are filled with &FF. 2. Filename is in upper case, 8 characters long, padded with spaces. '.COM' extension is assumed when accessed. 3. ROM starts at &c000. Therefore &c200 is the start of the first file.