Cromemco 4FDC, How do you format a disk?

From: allisonp_at_world.std.com <(allisonp_at_world.std.com)>
Date: Tue Jul 27 15:45:42 1999

> > Looking at the BIOS level implementation, it
> > seems that CP/M doesn't have a native format
> > command?
>
> That final statement sums it up. CP/M was not 'hardware aware' beyond the
> very basics needed to read/write data to an existing file system.

In the words of Shane Minor, Here's your sign!

The whole point of CP/M is to be logically disconnected from the mechanics
of the IO and the disks. The BIOS does the logical to physical
translation. There is no requirement for a LLF primitive for CP/M in the
BIOS BUT, there is nothing to prevent you from putting it there save for
one thing. 8080/z80 machines typically only have 64k of ram and many less
tossing off 500-1200 bytes to a routine that can be done as a utility
is a shameful waste of valuable ram.

> Keep in mind that in the time of CP/M, direct access to the hardware was a
> common thing the neither the operating system or the hardware attempted to
> prevent this. ...with the occasional exception of the disk controller

This whas discouraged as it made for non portable software. also due to
the limits of 8080/z80 there was little you can do to prevent direct
hardware access (no prived instructions in the cpu or hardware to enforce
it).

Allison
Received on Tue Jul 27 1999 - 15:45:42 BST