Date   : Tue, 08 Nov 1983 08:27:56 EST
From   : Keith Petersen <w8sdz@brl>
Subject: Re: FDC's for truly ancient S100 machines

Stan, I use a Morrow DJ2D floppy disk controller with two 8" drives.
It allows double-density double-sided (1.2 megabytes on one 8" disk!).
It comes with CP/M 2.2, Microsoft Basic-80 (MBASIC 5.21), and source
code for the CBIOS.  If you use the memory-mapped console port on
the FDC board, you can bring up CP/M immediately without having to
do any CBIOS configuration.  The FDC uses memory-mapped I/O and comes
standard with a starting address of E000h.  There is an option
(I recommend it) to have F800h as the starting address.  This would
use up F800-FFFFh which isn't too bad.  Dave Hardy has modified his
DJ2D to bank switch, thus allowing it to reside outside of the main
system RAM, but this requires a modification to the CBIOS software.
The DJ2D uses CPU transfers instead of DMA, so it does not conflict
with other boards that use DMA.  Mine has been used sucessfully with
both an IMSAI-8080 and a generic S-100 box that has a Cromemco ZPU
(Z80 CPU) card.  I do NOT use dynamic memory because I've had problems
with it when using the Z80.
--Keith