735 B
735 B
Memory Layout
On a 8080, there are no segments, the addresses are as displayed.
On on the 8086, a single segment with a value of 0x0100 is assumed. This implies that the first 4k of memory are not used.
The BDOS may be recompiled for starting at a lower address, in this case, the minimum memory requirement may be less than 64k.
| Start | Size | Function |
|---|---|---|
| 0xF000 | 4k | BDOS and hw drivers |
| var | BDOS data | |
| SP | var | Stack, growing down |
| Free memory | ||
| 0x0100 | up to stack | Transient Program Area |
| 0x0080 | 128 bytes | Command line and disk buffer |
| 0x0000 | 128 bytes | System data area |
Application program interface
It is using the call 5 convention with CP/M compatible syscall numbers.
File I/O is done via FCB blocks.