This page last updated June 04 2009. Contents (c) copyright Herb Johnson 2009.
S D Sales manuals are listed in my miscelaneous S-100 page under "SD Sales">. This page is for S D Systems.
I'll have more to say about SD Systems in the future. Meanwhile,
for more SD Systems information, software and hardware, check the following:
SD Systems documentation available
SD System Versafloppy II cards available
SD System motherboards available
my floppy drives and diskettes section.
tech specifications on floppy drives and media
Bruce Jones' work on the VF II
John Monahan's SD Systems work
Other's work on the VF II
commentary and code by Fred Scipione and Chuck Guzis
8080 code by Denver Hull
8080 code by Kevin Sisson
PROM 100 code from Andrew Lynch
I welcome comments and questions about this code. I've posted some suggested code and comments on this site with links as above. Read the code and comments before you do any work or ask questions.
To email me or to order follow this link. I have a number of SD Systems Versafloppy II S-100 controller cards,
unused with docs and some software. These cards were designed to
operate 8-inch or 5.25 inch floppy drives, soft sectored format,
single or double density. Their S-100 design is I/O mapped, uses
two 8-bit unidirectional data buses and 16 address lines, and requires
the older-style "phase 1" clock line. However, a simple LS7404 inverter
added to the card (a little solder and wire will do it) will flip the
"phase 2" line which most every S-100 system provides. There is no ROM or
serial I/O on this card.
These Versafloppy II cards were used by SD Systems in their
SDOS systems. SDOS is similar but NOT identical to CP/M.
Those systems used a ROM to support the SDOS BIOS
and SDOS format programs, and CP/M.
We have SDOS BIOS and ROM sources, the manual, and various
other software, all as described below. We offer no
warrenties on any of the software included with this card.
But there is plenty of information included to help you use
these cards and software or to write your own code.
I have a number of Versafloppy II S-100 cards available. Ask about price and availability.
Docs and code are available from this Web page, details below.
If you can fix or improve or add to the code, I'd appreciate
a copy to share with others who have bought this card. Code is posted on this site and linked
to this page, so check this page from time to time.
The Versafloppy II card I offer is a rev P version, with a WD 1795B FDC chip. The upper left corner has a trimpot, and an 8-pin IC, a LM310AN op amp. An earlier version (which I don't offer) is rev B or C. The upper left corner has a trimcap, and two IC's below it, one is an NE564 which is a phase-locked loop. The changes are in the diskette read circuits. Either board appears to work with the same software. Some customers have reported owning these boards with a WD 1791 FDC chip; this can be interchanged with the 1795 chip but the two chips function differently, and disks made with one may have errors when read with the other. Refer to the WD FDC documentation for more information.
This link is to a PDF copy of the SD Systems Versafloppy II manual with schematics, parts list, and hardware descriptions. This manual is also available as a photocopy for $5 plus postage and handling. This is copied as 30 sheets of 60 half-sized
manual pages. The manual is for rev C but has schematics and board photo for rev B & C, and also for rev N & P. thanks to John Monahan for the
revision information.
Note: the manual as printed does NOT include the data sheet for the WD1795 FDC chip.
The Western Digital 1791, 1793, 1795 and 1797 datasheet is available on my site at this link.
Or, we can provide a printed copy for $3 plus postage and handling.
Bruce Jones worked in the industry to "adapt DRI OS products for
a large number of S-100 and SBC products across the 8-bit, 16-bit and
32-bit range.". In late 2003, he provided me with very informative discussions and
code about 8080 and Z80 programming for floppy disk controllers. I've
posted much of that discussion on my site as per my links at the top of this page.
As of Jan 2004, I have from Bruce a set of working CP/M 2.2 BIOS, FORMAT,
and related Z80 code, for the Versafloppy II (and for other SD System
cards). His code (Z80 TDL format) supports 8-inch, 5.25 inch, and 3.5
inch drives. (He also includes a copy of the TDL assembler, ZASM, for CP/M.)
All his SD systems code, some CP/M programs, and additional docs in WORD
and PDF format are available from my Web site for free download.
One customer, Craig Landrum, who bought the card and software on Jan 2005, said
(er, at my request): "The sample boot and BIOS code included with the Versafloppy II
board were critical to getting my second IMSAI 8080 system
up and running. The documentation included for both the board
and the 1795 chip was a great reference, and by examining
the code while referencing the documentation, I was able
to what worked and get the job done quickly." I'll forward any questions to Craig
as he has requested.
For download, here is Bruce Jones' source code, docs and manuals: Some manuals for the Teac FD235 3.5" floppy are at this link. As of Oct 2007. I
have a variety of floppy drive manuals listed at this Web page for
sale as photocopies.
Bruce Jones has released all this work
"to the public domain", but please contact me if you want to post or
redistribute this work so updates can be made available. Also contact me
if you have comments or corrections. We offer no
warrenties on any of the software included with this card. But since 2006, Bruce has not responded to my inquiries. So I'll simply add new info to this page.
From SIG/M disk #26, here's JOHN J MONAHAN's 1981 version of an BIOS and FORMAT and BOOT, written in Z80 code.
In 2009, John Monahan has some SD Systems boards, and discussed with me his work on the SD Systems Versafloppy II controller.
Here's our email conversation and some photos and documents. He's provided an older revision schematic of the VF II, and
dicussion of how he's recently worked on this board and its software. John provided a BIOS source version and his own VF II diagnostic program source. See John's Web site "s100computers.com" for more information.
Another person, Fred Scipione, read Bruce's Z80 code in Jan 2005 and provided some comments and code. He has "unwound" the tight read/write loop so a slower processor can execute it. Follow the link for details. Send any comments to me and I'll pass them along. LIkewise I got similar code and comments from Chuck Guzis and I've added that to my Web pages. Thanks!
I've had requests for 8080 code for the Versafloppy II, so I asked some of my customers for conversions of Chuck Jones's code from Z80 to 8080. Denver Hull did a conversion to run on his IMSAI 2MHZ 8080 board, but he had problems making his VF II work. But the same card worked OK in the same system with Jones' Z80 code on a Cromemco ZPU Z80 card. Here's the 8080 code by Denver Hull, with some of his comments about problems. Code includes BIOS, boot, and format. Also, some 8080 memory test programs Denver obtained from other documents.
In May 2007, Kevin Sisson provided some 8080 code, which I've ZIPpped into
into this file. Here's Kevin's discussion of it. "I'm sorry it took so long for me to respond but I haven't looked at the code in a year and a half, and had to find all the pieces again. The file '8080-VF2.txt' explains what I did and has the code that I use on my S-100 system for reading in the boot code from a CP/M floppy. It is an ASCII text file. 'putsys.asm' runs from S-100 memory and copies the CP/M code in that memory to tracks 0 and 1 of a floppy (it is my version of SYSGEN). '4bios.asm' is the entire bios section of CP/M, written specifically for my system. Both of the asm files are also in ASCII, but might have some extra LFs or CRs."
have some SD Systems software provided to me in 1998 by Raymond Gandia as follows below. John Monahan noted, "One neat piece of software in that Gandia folder is the simple Zilog-mnemonic assembler that quickly spits out .COM code. Always wanted something like this!"
Any ".CPM" files are actually CP/M .COM files. SDSOURCE ZIP SD Systems SBC-200 dissassemblies of various sorts. From "Curt" ? I have some SD Systems SDOS disks, but they are 8-inch and I'll have to read them off someday. SDOS was
SD System's rewrite of CP/M.
To order from me or ask questions, email me as per the instructions
in this notice. SD Systems PROM-100 is a 2708 and 2716 EPROM programmer. The following code ASM files are courtesy of Andrew Lynch: Versafloppy I disk controller, with 33 pgs of BIOS and diagnostic source code, total 85 pgs.
Versafloppy II disk controller rev C Copied 2 pages per 8 X 11 sheet (half size) Other manuals:
Copyright © 2009 Herb Johnson
To return to my S-100 home page click here.
Versafloppy II S-100 cards, revisions
Versafloppy II manual, controller chip docs
Bruce Jones' software for Versafloppy II
Bruce Jones's sources and tool programs;
Bruce Jones's sources documents;
manual for WD179X & TMS279X FDC chip
ZASM manual to assemble code.
a document & code for SD Systems' VDB 8024 board upgrades by Bruce Jones;
docs & code on Z80 and 8080 operation of Versafloppy II by Bruce Jones;
docs & code for BIOS and FORMAT with the Versafloppy II by Bruce Jones.
Bruce's BIOS, FORMAT, VDB software and docs ZIP file
Bruce's updates and code fixes for his software
John Monahan's SD Systems work
Other's work on the VF II
Raymon Gandia code for Versafloppy II, SD Systems ROM disassembly
(I have not heard from Mr. Gandia in some time.) Any ".CPM" files are actually CP/M .COM files.
GANDIA ZIP Ramon Gandia's work on 3.5 inch support. Sysgen, bios, boot. No format.
Other SD Systems files
BIOS, ROM monitors, some format code. May be incomplete.
SDHEX ZIP SD System ROM dumps in hex
disassemblies and assemblies Herb Johnson has done. Some 8080 to Z80 translation tools, assembler and disassembler tools too.
RAMDISK ZIP Jade RAMDISK code for SD Systems, Jade "Double D" floppy controller.
HARD ZIP SD Systems hard disk executables
Also see John Monahan's work above.
SDOS
PROM16a.asm is nondiskette based code for 2716's
PROM16u.asm is CP/M code for 2716's
PROM08a.asm is nondiskette based code for 2708's
PROM08u.asm is CP/M code for 2708's
Here's the SD Systems docs I have available. Contact me to obtain a copy.
manual with schematics only, 30 sheets (60 pgs)
w/1795 docs, add 12 sheets (24 pgs)
see above for source code, S-100 card, and more information.
Expandoram User's manual, 30 pgs
PROM-100 rev c, with source code listings, 90 pgs (mostly code)
SDOS manual, 100 pgs
SD Monitor USer manual, (SBC-100) 23 pgs or SBC-100 & 200, 18 pges (copy)
Text Editor, Z80 Global Assembler, Linker, 50 pgs
SBC-200, 50 pgs
SD Systems Microcomputer Operating Manual, 35 pgs
ExpandoRAM II, with notes, 60 pgs
VDB-8024, with source code, 70 pgs
ExpandoRAM III, 32 pgs
I/O 8 serial, with driver source for RTC, 55 pgs
MPC-4 (smart serial controller), 100 pgs
OEM Price list, Aug 1983, 2 pages
2-page product descriptions for: IO/8, SBC 300, VFW-III, ExpandoRAM IV
Z80 Starter Kit, 115 pages (copy)
COSMOS or Communications Oriented Multi-User OS V2.17, 94 pages (copy)
...multi user OS, CP/M programs, for SBC-200 and Expandoram II
upgrade rev D ExpandoRAM II to 256KB; and errata, 14 pgs (copy)
Herb Johnson
New Jersey, USA
follow this link to email @ me
