Defining Disk Image Dump Standard

From: allisonp <allisonp_at_world.std.com>
Date: Tue May 30 17:07:54 2000

>I always figured the reason for the restriction was dumb boot PROMs, which
>only know how to do programmed I/O to the FDC, and 8" DD comes in too fast
>for typical 8-bit CPUs of the time to handle with PIO. If the boot PROM on
>a particular system is smart enough to set up DMA, no need to require SD.


it's an artifact of how people though the DDmedia was speced by IBM and
a lack of knowledge of CP/M boot as everyone just followed the book blindly.

Not all required {or even had it!} DMA to do DD, CCS didn't.

I'd add that DMA was mostly uncommon save for the more refined or robust
systems.

Allison
Received on Tue May 30 2000 - 17:07:54 BST