release dates of early microcomputer operating systems, incl. Intel ISIS

Dave G4UGM dave.g4ugm at
Tue Sep 15 03:34:51 CDT 2015

> -----Original Message-----
> From: cctalk [mailto:cctalk-bounces at] On Behalf Of Eric Smith
> Sent: Tuesday, 15 September, 2015 8:48 AM
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at>
> Subject: release dates of early microcomputer operating systems, incl. Intel
> I've been searching for introduction dates of early microcomputer operating
> systems, by which I mean only operating systems that run on computers
> using single-chip microprocessors such as 8008, 8080, and 6800, but not the
> LSI-11, IMP-16, HP 9830, etc.

But would you rule out the IM6100. Rather than being a PDP-8 on a chip, it was really more a chip that stole the PDP-8 OS....

> Intel's ISIS operating system for their MDS was first released in 1975, but I
> haven't been able to pin down a month. I'm looking for a more specific date
> for that, and for the releases of any prior microcomputer operating system.
> On Twitter, @hotelzululima suggested Motorola MIKBUG, introduced in
> 1974, but IMO it's a monitor, not an operating system. 

Define an "operating system". If you have no disks what could have gone into MikBug that wasn't there?
... but perhaps you meant DISK Operating System..

Actually to answer my own question the address of the character i/o routines "INCH" and "OUCH" are not designed for portability and 
later Monitors such as SWTBUG had to jump through (small) hoops to retain compatibility...

> Hzl also suggested
> Forth, which I also don't really consider to be an operating system in the
> traditional sense, but if there's evidence of Forth or a Forth-like language
> available for a microcomputer prior to 1976, that would be interesting as well.

Looks like FLEX for the 6809 was also 1976...

BUT I don't believe ISIS became an operating system until 1976 when ISIS II added support for disks....

and the ISIS II manual has 1976 on Bitsavers has 1976 as the first  Copyright.....


P.S. Often the search for "First" is fruitless, and folks will twist the arguments to suit their needs. So the Manchester SSEM and ENIAC argue constantly argue about the first program.
So although ENIAC first ran a program it was stored as acoustic waves, and the Manchester folks argue this was not an "electronic program".
Moving on is "Core" electronic storage? So did we have a long wait between the IBM 701 and the first machine with semi-conductor store when we had no computers using electronic storage...

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