Date   : Thu, 14 Oct 1982 03:37:00-EDT
From   : Jerry E Pournelle <POURNE@Mit-Mc>
Subject: M-drive etc.

There are at least two "pseudodisk" systems.  Both work.
Semi-disk works with any s-100 system (and also with trash-80
mod 3 and IBM pc) and any controller (using cpm-2.x).  The
Godbout M-drive or Warp Drive works only if you have a DMA disc
controller, preferably Godbout CompuPro Disk One, AND the
CompuPro 8085/8088 dual processor board.

The Semi-disk is dedicated memory; it is ONLY the "N=Drive"
(ours is tagged as drive 'N').  The Compupro Warp Drive (we have
named it Drive 'M' in our system) consists of ordinary memory
addressed properly plus a program to let you access it in the
right way.  It costs more than semi-disk but you can use the
momory when you use the 8088 (or go to an 8086 or whatever) as
ordinary memory; something you can't do with the N-drive
semi-disk.  Semi-disk is cheaper, and you can get more of it--up
to a megabyte.  We have 500K N-drive and about 256K M drive and
we like both.  They're fast and if you do  much assembly or
compiling you'll LOVE them...

See my BYTE peices for more details.