The recognition of Unix as standard operating system for 16-bit and 32-bit computers took a big step forward last week following two separate announcements.

IBM said it will offer Unix, under the name of PC/IX, for the PC in April in the US, and Digital Research released details of an agreement with AT&T under whose umbrella Unix was decised to develop a library of applications software for programmers and end users.

But there are divergencies in approach. In keeping with the PC philosophy of using proven - some would say out-of-date - technology, IBM has opted for an implementation of Unix System III.

Digital Research, meanwhile, will be concentrating its efforts on the latest version, System V, and the one designed by AT&T to be the commercial standard.

The significance of this decision is that AT&T has already signed agreements with the major chip manufacturers to standardise on System V.

Digital Research is already involved in this and is doing the 'port' on to the 286 chip for Intel. Motorola is doing its own port for the 68000 family of processors.

IBM's decision to implement a version of Unix on the PC opens a range of technical and scientific software for PC users as well as giving the Big Blue's seal of approval to the multi-tasking, multi-user operating system.

Interestingly, IBM has not opted for either of the two leading commercial implementations, Xenix from Microsoft and UniPlus from UniSoft. Instead it has gone to Interactive Systems, a small California based software house.

The indications are that IBM is avoiding dependence on one software company. The company is working on other versions of Unix for use on mainframes and other products.

In true IBM fashion it is not revealing any details nor will it discuss what operating system will be used on its present project, the Popcorn, believed to be based on the Intel 80186. Some IBM-watchers say Microsoft is not involved.