On August 5, 1986, Interactive Systems Corporation registered the isc.com domain name, making it 20th .com domain ever to be registered.
ISC’s 1977 offering, IS/1, was a Version 6 Unix variant enhanced for office automation running on the PDP-11. IS/3 and IS/5 were enhanced versions of Unix System III and System V for PDP-11 and VAX. ISC Unix ports to the IBM PC included a variant of System III, developed under contract to IBM, known as PC/IX (Personal Computer Interactive eXecutive, also abbreviated PC-IX), with later versions branded 386/ix and finally Interactive Unix System V/386 (based on System V Release 3.2). ISC was AT&T’s “Principal Publisher” for System V.4 on the Intel platform. ISC was also involved in the development of VM/IX (Unix as a guest OS in VM/CMS) and IX/370 (native Unix on the System/370). They also developed the AIX (Advanced Interactive Executive) for the IBM 6150 RT, again under contract to IBM, although IBM awarded the development contract for AIX version 2 for the PS/2 to the competing Locus Computing Corporation.
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 wasn’t quite a fully fledged word processor. PC/IX omitted the System III FORTRAN compiler, 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 directly addressed the XT hard-drive 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 the PDP-11/23.