S100 Computers

Home S-100 Boards History New Boards Software Boards For Sale
Forum Other Web Sites News Index    
- CompuFone
CompuFone was Computalker's second and last S-100 board. It came out in 1984.


The board was S-100/IEEE-696 compatible and contained the following sub-systems.

An FCC-approved direct-connect to a telephone interface.
A Touch-Tone generator and decoder.
A speech digitizer.
An analog multiplexer that can select any of eight sources for connection to the speech digitizer/telephone line interface.

The direct-connect telephone interface was capable of recognizing tones on the telephone network such as dial tone, ringing and busy. The interface could pulse or Touch-Tone dial, allowing CompuFone to originate calls as well as answer them.

Touch-Tones could be generated at any time and can be sent to the telephone interface for transmission. Touch-Tones can also be received and  decoded to allow control of the program running the CompuFone. The speech digitizer subsystem functioned as a "solid state tape recorder" by allowing speech or other sound to be saved in either RAM or mass storage and reproduced on playback. The speech digitizer used a hardware data compression technique to reduce the memory and mass storage space needed to record messages. This data compression technique achieved a 5-to-1 compression over an A/D converter. This allowed acceptable quality speech to be recorded and played back at a rate as low as 1.25K per second. This kind of compression made the storage of messages on floppy disks feasible. A total of five sampling rates were available, from 1.25 to 4K bytes per second.

Finally, the analog multiplexer allowed any one of eight sources to be connected to the internal audio bus. The internal audio bus, which feed both the telephone line and the speech digitizer, was buffered and was available at a connector (line-out pin) for attachment to an external amplifier and speaker. Seven of the lines connected to the multiplexer were:- microphone, line-in, three aux lines, the Touch-Tone generator, and speech digitizer output. The analog multiplexer used three bits of the boards base port to control the selection of input. The eighth choice is zero, which the documentation says was the telephone line. However, the telephone line was always connected to the internal audio bus. I believe this "selection" allowed the telephone line to be connected to the audio bus without attenuation and without being mixed with any other source.

I do not have a manual for this board. If you would like to donate one (or a better picture) please let me know.
In May 1984 Randy Reitz wrote up an excellent review of this board for Microsystems (Vol 5, #5, p44). 


Computalker  S-100 Boards
CT-1    CompuFone


This page was last modified on 10/25/2013