Last modified on 28 April 2018, at 10:39

Graduate Software

Revision as of 10:39, 28 April 2018 by Arnoldemu (Talk | contribs) (Structure of a utility ROM)

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.