On other pages, we have the following:
a few IMSAI front panel switches, click here.
Here is a list of the IMSAI and Altair bus lines.
For a list of all S-100 docs click there.
And here is how to order S-100 stuff and to email @ me.

IMSAI history

Here's the FIRST "clone" computer: the IMSAI 8080, offered by IMS Associates Inc. late in 1975 after the introduction of the MITS Altair 8800. While not a copy of the Altair, it was designed and sold to be card and bus-compatible with the Altair 8800. Consequently over 100 manufacturers created S-100 products and so established a market requirement of compatibility which later became "clones" in the IBM-PC world.

IMSAI's history preceeded the Altair but it is remembered best for the IMSAI 8080 computer and related products. IMS Associates, Inc. was founded in 1973 by Bill Millard. The company provided engineering and software services. Sometime during 1975-76 it became known as IMSAI. Thomas "Todd" Fischer, an early IMSAI employee who later acquired rights to some IMSAI products and its name, describes on his site that IMSAI was designing a multiple 8080 processor system called the "Hypercube" in 1975. Meanwhile, MITS announced their Altair 8800 late in 1974. IMSAI decided to replicate the Altair for use with this system, and subsequently to offer it as a stand-alone product.

The IMSAI 8080 was designed by Joe Killian, and advertized in Popular Electronics late in 1975. The first units were shipped sometime in December 1975. The first IMSAI 8080 contained three cards: a motherboard with an Altair-like 100-pin bus connector, a front panel card with switches and lights like mainframe and minicomputers of the day; and a CPU card with a 2MHz 8-bit Intel 8080. This package was sold for the amazing initial price in 1975 of $400. A fourth card for memory was added at some point. The price rose during 1976 at various points, to about $500.

Most S-100 fans today say the IMSAI is better engineered than the Altair 8800. At the time MITS in their customer magazine called it a "copy". IMSAI ads of the period referred to their bus and cards as "MITS compatible". Subsequent plug-in card manufacturers referred to their products as "MITS/Altair bus compatible". The name "S-100" was created later, a term disliked by MITS management. But that bus cross-compatibility initiated an industry of S-100 compatible cards that led to the formation of over 100 computer companies large and small, producing (more or less) compatible cards and systems. A list of those companies is on my . A subsequent version of the S-100 bus wasthe IEEE-696 design which was in use in the late 1970's but not approved by the IEEE until 1983. S-100 bus history is described in this document.

IMSAI (or IMS Associates Inc.) went bankrupt in late 1979. Meanwhile, in 1976 Bill Millard co-developed and controlled ComputerLand, an early chain of franchised computer stores which did business through the mid-1980's.

IMSAI and CP/M

IMSAI was an early adopter of CP/M and floppy disk drives, starting in 1976. Check my Digital Research page for the IMSAI and CP/M story. According to Todd Fischer at IMSAI, "the first disk controller configuration was the two-board IFM/FIB single density only controller that ran IMSAI's CP/M 1.3. The next generation (c. early 1977) was the DIO/PDS board set which ran the enhanced proprietary version of CP/M called IMDOS. First, there was [IMDOS] version 2.02, then 2.05, then 2.07, and finally IMDOS II (Dianne Hijcek's last-ditch effort at propping up the value of the third generation IMSAI hardware."

Todd updated the above description, in a comp.os.cpm post for Jan 29 2007, quoted with permission here. "The IMSAI DIO series of memory mapped controllers handled Double Density just fine with the MPU-C 8085-based processor running at 3 MHz., and just as well with the original IMSAI MPU-A running at 2 MHz. We sold a boatload of disk subsystems to first and second generation IMSAI system owners. Our double-density formats included 256, 512, and 1024 (long sector) sector lengths. The mid-1977 second generation controllers closely followed the IBM 3740 formats and subsequent variants for media read/write compatibility. The original DIO-A of early 1977 used a proprietary double density format which was unique to IMSAI.

Todd continued: "For the record, the original IMSAI IFM/FIB intelligent DMA disk controller of mid-1976 was debugged and rendered eminently usable and reliable by Glen Ewing, consultant to IMSAI and fellow instructor with Gary Kildall at the Naval Postgraduate school in Monterey, CA." More of Todd's comments are on my Digital Research Web page.

Fischer-Freitas and imsai.net

Todd says IMSAI was in business until October of 1979, when its assets were sold at a bankruptcy auction, and its and intellectual property and manufacturing rights were acquired by Fischer-Freitas Corporation. Some items were acquired by Fulcrum, later known as WW Component Supply. The IMSAI product line continued to be offered as a division of Fischer-Freitas Corporation for some time thereafter, says Todd. In 1998 Fischer-Freitas Company announced some new products based on the IMSAI and opened a Web site at imsai.net.

By 2001 their products, information and services included some of the original IMSAI systems and cards. In 2003 they had new products based on a new IMSAI using the IEEE-696 bus standard and some IMSAI bus lines as well; and an IEEE-696 I/O card which supports mass storage. Since (about) 2005-06 Todd is the owner of the "IMSAI" trademark and the imsai.net Web site.

(Note: Info from Todd Fischer is from Todd's imsai.net Web site, and from private and public correspondence. It is referenced here with his permission. More info on the history of IMSAI and Fischer-Freitas, and these newer products, can be found on their site. I'm pleased with the good will I've received from Todd Fischer and his company. - Herb Johnson)

Fulcrum computers

In private communications from 2004, Todd Fischer of IMSAI told me a bit about the history of "Fulcrum" computers, as follows. A company called "W.W. Component Supply" of San Jose, California acquired and sold some goods from the (original) IMSAI Inc. bankruptcy and auction. They advertised IMSAI products for a short period of time. Threatened with a law suit for trademark infringement, W.W. Component changed the name of their products to "Fulcrum", and continued in business until the late 1980's.

In 2006 I acquired a 1981 "Fulcrum" catalog by WW Component which refers to their "exclusive" IMSAI/Fulcrum product line.

Chris Raymond of Fulcrum

In late 2004 I was contacted by Chris Raymond. He designed a Fulcrum product, the Fulcrum VIO-X, first sold in late 1981. He wanted that card from me as a momento of that work. I asked about his VIO-X design versus the IMSAI VIO card, and what he knew of Fulcrum. He wrote:

Hi Herb, as I recall the VIO is an IMSAI product, is that correct?  The
VIO-X was a completely different design, not an IMSAI product, although it
shared the 80x24 format.

If I remember correctly, the VIO was a memory mapped design which required
a software driver to keep track of cursor position etc., and handle scrolling,
which was slow because the driver had to move all the characters around
one by one in the screen buffer.  I think it produced glitches on the display
whenever the software wrote to it.  The VIO-X on the other hand was designed
to look like a UART to the software - it responded to escape sequences and
commands the same as a Lear Siegler ADM-2 terminal.  There were no screen
glitches, scrolling was virtually instantaneous, and the software driver
was identical to a serial port.  The board had an 8085 microprocessor with
about 2K of software in EPROM to accomplish this.  The design was based on an
Intel 8275 [video processor chip] app note and worked pretty well, IMHO.

I designed the board at the suggestion of my friend Dave Needle who needed
a video terminal as part of his video game development system.  Although he
only needed TTY capability, I decided to implement conversational and
block modes compatible with the ADM-2 (which I used daily at my job at Tandem
Computers).  In addition, I took advantage of the invisible character
attribute feature of the 8275 chip which allow attributes such as
blinking, underline or inverse video to be turned on and off without a blank
character in front of the field, although the default mode used visible attributes
for ADM-2 compatibility.

The original design generated a monochrome video signal reasonably close
to the NTSC standard.  Brent Wright (WW Component Supply, later called
Fulcrum), who manufactured the board, asked me to change the design to
work with a Ball Brothers monitor (he had a lot of them on hand), which
required different timing of the HSYNC signal.  As I recall, the board was
configurable either way although I don't remember for sure.  Brent took my
original design, which I implemnted on a wirewrap board, and layed out a
PCB.  He sold a number of them but I don't know how many.

I also wrote the original manual which I understand was fairly worthless.
Hopefully the extended version (which I didn't write) is more useful.

So anyway, if you have a board lying around let me know how much you want
for it.   I don't know the business relationship between IMSAI and Fulcrum,
sorry I can't shed any light there.  I don't have a web site to link to
either, unless people want to look at baby pictures... thanks for your
interest in this stuff, it brings back some fun memories.  Cheers, [and]
Thanks,

Chris

WW Component Supply

See also "Fulcrum computers" above. Fulcrum was the previous company name for WW Component Supply. Some Fulcrum manuals have in fine print "distributed by WW Component Supply Inc.".

In August of 2006 I was contacted by Rae Stiening, who discussed WW Component Supply, and his design of the Omniram for Brent Wright. If anyone has information about Mr. Wright, contact me so I can pass it along to Rae. - Herb Johnson

Brent Wright was one of the W's in W&W Component Supply. Brent got his start
in the component business by working for Mike Quinn at Oakland Airport's
North Field. It was a good start because Brent was the best components man I
ever met. I do know that the Omniram came after the VIO-X because the first
job I did for Brent was to write code for the
VIO-X so that it emulated the Bee terminal used by Cromemco.

I enjoyed visiting W&W's store at 1776 Junction Avenue in San Jose CA
on weekends. I don't know when W&W opened but would guess that it was around
1980. At some point Brent told me that he had located a supply of
inexpensive 2K static ram chips and that 32 of them would just barely fit on
an S100 card. I agreed to wire wrap a prototype and we agreed on terms. The
contract was a few words on the corner of a paper napkin that happened to be
nearby. W&W sold lots of Omnirams because Brent's choice of memory chip
permitted it to be sold a price far below that of competing boards.

From "contract" to first production Omniram's was
about six weeks. Brent worked really fast. There was a single page ad in
Byte magazine when we were ready to ship.
 
By the time the Omniram was produced neither S100 bus products nor W&W
Component Supply had long to live as viable commercial enterprises. 

W&W [later] moved to another location in San Jose and closed down
in approximately 1988. W&W's building is now (2006) a print shop
and a Fry's Electronics megastore occupies the entire block across the street.

At the time of the Omniram I was interested in the application of
microcomputers to astronomical data acquisition. The most recent project
that I managed is described at [this Web page].  

Regards, Rae Stiening, in MA

Rae provided this photo of WW Component Supply taken in the mid-1980's, at their Junction Avenue address in San Jose, CA.

Rae says more information about Mike Quinn, a well-known surplus and electronics dealer in Oakland since the 1960's, is described on a section of the imsai.net Web site. The site said Quinn's shop is still in business as of the 21st century. HOwever, I was told that the store closed in the fall of 2006.

IMSAI and Fulcrum Documentation S-100 docs list

Note: I do not offer "sets" of manuals. I offer manuals individually or in some cases I'll identify sections of manuals available seperately. By and large most companies created "sets" of docs from individual manuals for cards and software. Also it's cheaper to YOU if you don't buy docs for card or software you don't have anyway! I only offer copies, by the way, not originals.

I may have some IMSAI parts or related parts: check my S-100 items for sale page accordingly.

IMSAI parts available

Here's some UNUSED IMSAI switches - originals from C&K, not copies!
-------------------------------------------------------------------

  $4 each   C&K toggle switches, identical to the ones purchased by IMSAI
  $3 w/o    for the IMSAI 8080, with RED, not BLUE, plastic levers. These are
     red    the "address" switches, *NEW UNUSED*. (These will not work as
     cap    the "control" switches as they do not have a center position.)
            The caps can be removed with care and used seperately.
            Modest quantity available, minimum order $12. Caps not available
            seperately.

IMSAI and related documentation available (copies)

IMSAI 8080 System User's Manual and chapters

       IMSAI 8080 Microcomputer Systems User's Manual, 
        rev 1 1976, also see rev 4
            intro, cabinet, motherboard, CPA (front panel), MPU (processor card). 146 pgs
            (This is the manual for the processor card, front panel, case
            power supply, and motherboard for the "IMSAI 8080"!)
            Schematics included for items noted. Includes mechanical
            drawings and assembly, IMSAI bus description, test code.

        If you only want individual chapters of the System Users Manual:
            Introduction, overall description and testing, component assembly: 44 pgs
            MOtherboard, 20 pgs
            Power Supply, many photos, 24 pages
            CPA (front panel), 40 pgs with updates
            MPU (CPU card) 14 pages
         
       additional System User Manual chapters on other cards, with schematics, are extra as below:
            chapter on PROM-4, 14 pgs
            chapter on PIO, 20 pgs                                  
            chapter on SIO, 30 pgs; also see rev 4
            chapter on PIC-8, 20 pgs
            chapter on CRI, w/source listings, 32 pgs
            chapter on SCS (Self-contained op sys), source, 74 pgs
            chapter on RAM 4A, 10 pgs; also see rev 4
            chapter on RAM 4, 10 pgs
      later version schematics, layouts:
            CPA rev 4, 4 pgs
            SIO 2-2 rev 3, 4 pgs
            MPU-A rev 4, 3 pgs
            RAM 4A-4 rev 3, 2 pgs
            PS-C-D rev 1, 2 pgs

Other IMSAI product manuals

      IMSAI MIO manual (from copy), 70 pgs
      IMSAI PIO-6 manual (from copy), 30 pgs
      IMSAI RAMIII reference man, 50 pgs
      IMSAI Dynamic Ram system User Man (RAM-16, RAM-32, RAM-65), 120 pgs
            sections for ONE model only (RAM-16 OR -32 OR -65), 68 pgs
      IMSAI VIO Users manual, 200 pgs
          schematics, source listing, video character bitmaps
 
Other IMSAI system manuals (PCS or VDP systems)

      PCS 80/30 reference manual, 185 pgs
            MPU-B, VIO, IKB-1, PS-28U. CP/M 1.33 references!
      IMSAI PCS-4X Microcomputer Sys Users Man
            CDIO, MDIO, DIO-D, RAMIII, MPU-B, PCS-44; 200 pgs
            RAM III chapter only, 36 pgs
            MDIO chapter only, 34 pgs; other chapters available seperately
      PCS 80/15 reference manual (MPU-B) - ask for details
      IMSAI VDP-80 Users and Ref Man (VIO, MPU-B), 250 pgs
      VDP-80 user manual, 70 pgs
      VDP-80 reference manual, 120 pgs
      VDP-40 Operating manual, 70 pgs
      VDP-4X operators manual, 90 pgs

IMSAI floppy and hard drive manuals

      IMSAI Floppy Disk sys User Man (Calcomp drive) May 1978, ?? pgs
            IFM chapter, 26 pgs w/schematic
            FIB chapter, 26 pgs w/schematic but not firmware
            FIB firmware listing 32 pgs
            floppy disk system user manual 60 pgs

      IMSAI FPS, FLB, FDS, other info ??? pgs
            Calcomp 140 disk drive OEM manual, 40 pgs

      IMSAI DIO Controller User Manual (Persci drive)
            DIO, PDS rev 1 11/77 w/ 5/78 eratta sheets, 100 pgs
            (Imsai) PerSci 277 Diskette drive manual, 100 pgs
            (Imsai) PerSci/IMSAI runnup procedure, 75 pgs
            (Imsai) PerSci Maintenance manual, 40 pgs

      IMSAI Diskette system Reference (PDSII,DIO, FIF), 150 pgs

      IMSAI HD-10 (CDC 9427H cartridge disk drive) reference manual, 200 pgs
            includes HD-10, DCFIO controller / formatter
            DA-01 S-100 bus adapter,
            Control Data copies of info on CDC 9427H drive


IMSAI and related software documentation available (copies)

             IMDOS V2.05 Users manual, 250 pgs
             IMSAI Fortran IV user manual V1.0, 100 pgs
             FORTRAN IV V3.05, 155 pgs
             IMSAI CBASIC user manual, 40 pgs
             IMDOS BIOS listings, 16 pgs
             IMDOS Users Manual, 340 pgs
             IMDOS BASIC-E manual, 80 pgs
             IMSAI 8K BASIC, 100 pgs
             CBASIC users manual, 80 pgs

Fulcrum & WW Component Supply documentation

             MPU-Z Z80 User's Manual, June 1984 prelim. 12 pgs
             MPU-Z Z80 Ref. Manual, Mar 86 prelim.  27 pgs
             OMNIDISK Unit DMA Disk Controller Tech Ref, June 86, 140 pgs
             VIO-X user manual A1.1 8/81, w/addendum C1 11/81, 56 pgs
             Monitor program for MPU-Z and OMNIDISK, Mar 1986, 20 pgs
                 paper listing only, ZILOG Z80 source for M80 assembler
                 two columns of listings per page, many comments
             OMNIDISK Firmware source listing, "AA1.ASM", 50 pages
                 two columns of listings per page, 2 years of fixes from
                 1983 initial source date
		 WW Component Supply "Fulcrum" product catalog, 1981, 12 pages

Copyright © 2009 Herb Johnson