California Computer Systems -
2422 FDC Board
This was a fairly standard FDC board.
The only thing unusual was that by modifying the board you could get it to work
with PerSci drives. It utilized the Western Digital 1793 (non inverted data bus
1791) FDC chip.
CCS's 2422 Floppy
Disk Controller supported single- and double-density data formats, single- and
double-sided 5.25" and 8"
drives,
and provided a 2K ROM containing software debugging routines and a bootstrap
loader for loading CP/M (Digital Research's single-user operating system) from
diskette. The 2422 was designed especially for use in CCS's system 2210, but
provided a number of user options for compatibility
with
other
systems
and
software.
The
2422
incorporated
the
following
features:
-
Ability
to
control
up to
four drives
in
any combination of single-sided or
double-sided
5.25"
and
8"
drives.
-
Compatibility
with
the
IBM
3740
and
System
34
standards
for single-
and
double-density
diskette
formats.
-
ROM-resident
monitor
program
and
bootstrap loader.
-
Auto
Boot
option
allowing
CP/M
to
be
booted
in
on
reset.
-
Compatibility
with either
Shugart
or
Persci
drive buses
-
Compatibility
with
IEEE
proposed
S-100
bus
-
A
compatible version of CP/M that supports single- and double-density diskette
formats in 128, 256, 512, and 1024 bytes
per
sector.
The well written manual can be obtained
here.
The schematic can be seen
here.
"This board is modeled after the CCS Rev B controller. Incorporated are a couple
of the known fixes to correct some timing problems. The "Memory Map" prom option
was not included in this rev, which I have never seen used, and was also not
supported in the CCS BIOS. There is an option for using GALs instead of the
bi-polar proms (74s287's), which are hard to find, and need specialized
programmers. Two 22V10 GAL's replace the CCS U22, and U23 proms. I structured
the GAL pins in way that you can use either the GALs, or the proms, on the same
board with just 1 jumper. I also added the option for the Pololu 5V regulator.
There is a cut trace option on the solder side if one wanted to use a more
common 2732, vs a 2716 / 28C16. There is also a set of jumpers for the 8" "TWO
SIDED" signal to be emulated for either Drive A, Drive B, or ALL drives, if you
use drives that do not provide the "TWO SIDED" signal (The CCS controller, and
the Compupro Disk1A, needs this signal). This is especially useful when using
Drive Emulators, or using 3.5" drives as 8" drives, etc.. I added a mini led to
indicate that "TWO SIDED" is enabled. Functionality of this board, as well as
the chip layout, matches that of the CCS 2422 Rev B controller."
Greg Beat has submitted the following support information for a reproduction of
this board done by Richard Camarda and Todd Goodman. See
here
CCS_Controller_Software.pdf
CCS_Monitor.Zip
The code for the GALs is here:-
U22B_GAL.jed
U23B_GAL.jed
KiCAD Files.ZIP for the
above Rev E board. (Supplied by Rich Camarda/Todd Goodman). Use KiCAD 4.0.7 or
later.
Other California Computer
Systems S-100 Boards
16K RAM
2065 64K RAM
2066 64K RAM
FDC
Z80 CPU
SIO
Serial & Parallel
Other Boards
This page was last modified
on
02/28/2021
