The title pretty much says it all. I'm looking for information about an operating system called I/OS by a company called Infosoft in the early 1980's. I think it might have been a CP/M variant and it definitely ran on a Z80 based microcomputer with an S100 bus.

Some background: Sometime in 1990 or 1991 I purchased 5 or 6 Sony LDP-1000 LaserDisc players from a salvage shop. These were part of interactive video labs used by the Army in (I assume) the 1980's and were interesting enough that I purchased one of the labs in it's entirety. A big wooden box with the laser disc player, a printer, Amdek color monitor, 1200 baud modem, and a strange little Z80 based computer to control the laserdisc player (via RS-232) and run whatever software / operating system it was supposed to run... I only ever tried using the computer 1 time, and my memories from the time are quite fuzzy. Years later, when I parted out the box, I took the power supply, PC boards, and everything interesting (except the floppy drive) and stored everything in my pile of junk.

Recently, I just found the lab was called a C3 JOIN system, and that it ran "I/OS Operating System version 2.36". But my google-fu didn't turn up anything, so it's either really obscure - or I'm just not using the right terms (obviously the name I/OS is similar enough to iOS to skew the search results).

3 Answers 3


The first page of the article Getting Compatible with CP/M implies it was an alternative name for Infosoft's TSA/OS, and was indeed a CP/M variant.

  • This is indeed helpful (thanks alephzero!), but I am still having difficulty obtaining any substantial information about Infosoft or the TSA/OS (I/OS) operating system, including but not limited to possible documentation and/or disk images.
    – Geo...
    Commented Oct 3, 2018 at 11:18

AFAIK Mostek M/OS-80 was a licensed derivative of an Infosoft CP/M-compatible operating system. There is an M/OS-80 manual on bitsavers in this directory:



There is a brief mention of it in this list:

That might be referring to the brief news story on p2 here:
See "8080/Z80 operating system has multiuser capability"

Someone here claims to have contacted the author:

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .