[TUHS] PC Unix

Paul Ruizendaal pnr at planet.nl
Wed Apr 7 17:52:54 AEST 2021

> I developed LSX at Bell Labs in Murray Hill NJ in the 1974-1975 
> timeframe.
> An existing C compiler made it possible without too much effort. The 
> source was available to Universities by then. I also developed Mini-UNIX
> for the PDP11/10  (also no memory protection) in the 1976 timeframe.
> This source code was also made available to Universities, but the source
> code for LSX was not.
> Peter Weiner, the founder of INTERACTIVE Systems Corp.(ISC) in June 
> 1977,
> the first commercial company to license UNIX source from Western
> Electric for $20,000. Binary licenses were available at the same time.
> I joined ISC in May of 1978 when ISC was the first company to offer
> UNIX support services to third parties. There was never any talk about
> licensing  UNIX source code from Western Electric (WE) from the founding
> of ISC to when the Intel 8086 micro became available in 1981.
> DEC never really targeted the PC market with the LSI-11 micro,
> and WE never made it easy to license binary copies of the UNIX
> source code, So LSX never really caught on in the commercial market.
> ISC was in the business of porting the UNIX source code to other
> computers, micro to mainframe, as new computer architectures
> were developed.
> Heinz

The Wikipedia page for ISC has the following paragraphs:

"Although observers in the early 1980s expected that IBM would choose Microsoft Xenix or a version from AT&T Corporation as the Unix for its microcomputer, PC/IX was the first Unix implementation for the IBM PC XT available directly from IBM. According to Bob Blake, the PC/IX product manager for IBM, their "primary objective was to make a credible Unix system - [...] not try to 'IBM-ize' the product. PC-IX is System III Unix." PC/IX was not, however, the first Unix port to the XT: Venix/86 preceded PC/IX by about a year, although it was based on the older Version 7 Unix.

The main addition to PC/IX was the INed screen editor from ISC. INed offered multiple windows and context-sensitive help, paragraph justification and margin changes, although it was not a fully fledged word processor. PC/IX omitted the System III FORTRAN compiler and the tar file archiver, and did not add BSD tools like vi or the C shell. One reason for not porting these was that in PC/IX, individual applications were limited to a single segment of 64 kB of RAM.

To achieve good filesystem performance, PC/IX addressed the XT hard drive directly, rather than doing this through the BIOS, which gave it a significant speed advantage compared to MS-DOS. Because of the lack of true memory protection in the 8088 chips, IBM only sold single-user licenses for PC/IX.

The PC/IX distribution came on 19 floppy disks and was accompanied by a 1,800-page manual. Installed, PC/IX took approximately 4.5 MB of disk space. An editorial by Bill Machrone in PC Magazine at the time of PC/IX's launch flagged the $900 price as a show stopper given its lack of compatibility with MS-DOS applications. PC/IX was not a commercial success although BYTE in August 1984 described it as "a complete, usable single-user implementation that does what can be done with the 8088", noting that PC/IX on the PC outperformed Venix on the PDP-11/23.”

It seems like Venix/86 came out in Spring 1983 and PC/IX in Spring 1984. I guess by then RAM had become cheap enough that running in 64KB of core was no longer a requirement and LSX and MX did not make sense anymore. Does that sound right?

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