724 B
724 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| +-+-+-+ |F000|4k|BDOS and hw drivers| ||var|BDOS data| |SP|var|Stack, growing down| |||Free memory| |0100|up to stack|Transient Program Area| |0080|128 bytes|Command line and disk buffer| |0000|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.