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Hit Counter     rev. 01/11/15

IMSAI History: The 8048 Control Computer  
To view some early images and concept advertising click here

Background-  The IMSAI 8048 Control Computer was one of the products envisioned in early 1977 when Microprocessor chip-maker Intel released confidential pre-release information to IMSAI regarding their about-to-be-announced 8048 controller chip.  Always ready to be in the forefront of technology, IMSAI's Marketing and Engineering departments developed the single board implementation of that chip and it's attendant memory and control components.  A release bulletin dated August 1977 reads:

IMSAI NEWS RELEASE - 8048 Single Board Control Computer

San Leandro, California, U.S.A. - IMSAI Manufacturing Corporation is pleased to announce the IMSAI 8048 Control Computer. This complete control computer on an 8 1/2 x 10" board is based on Intel's new 8048 micro computer chip. It is the World's First Single Chip Control Computer that contains all of the following features:

1. 8 Bit CPU
2. 4.2 Microsecond instruction cycle, 96 instructions
3. BCD arithmetic capability
4. 1 K words of ROM or compatible EPROM program memory
5. 64 words of internal register memory
6. 27 I/0 lines
7. Internal Timer/Event counter
8. Oscillator and Clock Driver
9. Reset circuit
10. Interrupt Circuit
11. Uses Single 5-Volt Supply
12. TTL Compatible

In addition, to create a one board user programmable controller suitable for use with model railroads, energy conservation systems, ham radios, household lights, light shows, and a myriad of other applications, the following system features have been added:

1. Cassette Interface.
2. Serial I/0 (RS232, current loop).
3. 5 relays capable of handling 2 Amps at 220 Volts, 3 Amps at 110.
4. 1 K (optional additional 1 K) of user programmable program memory.
5. DC power supply or battery operated.


The Intel 8048/8748/8035 micro-computer chips are designed to accommodate three separate memory spaces: Program memory, Internal data memory (registers), and external data memory.

The Internal data memory is divided into 4 separate, though contiguous, areas: Register bank 0, register bank 1, Stock, and user RAM.

The 8048 series chips are intended for dedicated controller applications. As a result no provisions were made to modify program memory since this is usually a ROM or EPROM. IMSAI has solved this problem by using the same block of RAM as both program memory, which allows the contents to be executed, and as external data memory, which allows the contents to be read or written. Since direct addressing is only provided for 256 bytes of external data memory automatic paging is provided in the monitor program.

The monitor (described below) is stored in the resident ROM of the 8048 or EPROM of the 8748, or else it is located in external ROM or EPROM when an 8035 is used.

The IMSAI 8048 Control Computer is available in two versions. In the ROM version the system monitor is contained in the 8048/8035 chip itself or in an external ROM. In the other version the monitor is contained in the 8748/8035 chip itself or in a 2716 2K byte EPROM. Both versions contain the 64 byte internal register RAM and 1K byte of external memory with space for an additional 1 K byte of external memory.


IMSAI 8048 Control Computer provides the following functions:

1. Enter programs into program memory.

2. Enter data into both internal and external memory.

3. Examine any memory location, internal or external.

4. Execute a user program in stand-alone mode.

5. Execute a user program with software breakpoints for debugging.

6. Save/retrieve user programs on cassette tape.

7. Save and retrieve programs from serial port; e.g., teletype paper tape reader.

The IMSAI 8048 Control Computers are offered in both assembled and kit form/Prices are as follows:

IMSAI 8048 Control Computer (ROM version) $249 Kit, $299 Assembled

IMSAI 8048 Control Computer (EPROM version) $399 Kit, $499 Assembled

Five Volt Power Supply $99    (U.S. Domestic Prices)


REV 8/77

Some advertising images:   (click on image for larger view)

complete_cntrl_1.jpg (279867 bytes)This ad appeared in the program for the First West Coast Computer Faire in April of 1977.  It is unique in that it features IMSAI employees.   Seen in this ad are IMSIDER editor Barbara Otto (lower left), Finance Manager Ed Gingrass (above Barb), Operations Manager Marvin Walker (to Ed's right), Programmer Al Levy (to Marvin's right), Customer Service Tech Al Reno (to Levy's right), an unknown actor (below Reno), another unknown actor above and to his right), and Sales Associate Michael Moon to the far right).

complete_cntrl_2.jpg (290305 bytes)
This ad uses actors, except for IMSAI's Finance Director Hersch Mandelman as the "Milk Man".

8048_raw1.jpg (140771 bytes)
A raw ad photo of one of the five 8048 Control Computer prototypes I built while working in Engineering for IMSAI in March of 1977.
8048_raw_notebook.jpg (91390 bytes)
Another of the five prototypes is shown in this early concept photo of a "notebook" computer, to be packaged along with tutorials and design sheets.  It was released with a solder-masked board and manual, all neatly packaged in an attractive white 3-ring binder.

Concept_8048_1.jpg (200126 bytes)


One of the aborted ad campaigns for the new 8048 was "Micromania".  This is the first of the four images in our archives.

Concept_8048_2.jpg (154679 bytes)


This is the second of the four "Micromania" images in our archives.

Concept_8048_3.jpg (195955 bytes)
This is the third of the four "Micromania" images in our archives.

Concept_8048_4.jpg (187682 bytes)
This is the fourth of the four "Micromania" images in our archives.

8048_control.jpg (90765 bytes)
This was the most common form of the 8048's that were shipped, mostly as kits.  I believe that fewer than 300 were sold.

8048_express.jpg (82692 bytes)This was a limited production package for the IMSAI Express version of the 8048.  It was targeted for the Model Railroad market and garnered much attention from the hobby community but, overall,  was not successful.  Fewer than 50 of these were produced.