The Gazette 1990

GAZETTE

JULY/AUGUST 1990

UNIX

and Networking explained

happened was because of the incredibly huge amount of software being developed for the IBM standard. These packages included word processing, spreadsheet, project management, ideas pro- cessors, databases, communica- tions, desktop publishing, . . . the list is endless. Wang users were deprived of all these packages except in a relatively small number of cases. On the hardware side also, manufacturers were making pieces of equipment that did weird and wonderful things like read books directly into the computer, talk, make telephone calls, control machines . . . etc. Here also these were not available to unfortunates, myself included, who did not buy the standard. So today where do we stand at the microprocessor end of the computer market? Should we go for UNIX or should we go for MS- DOS? Before I answer that question let us look at how the t wo operating systems differ. UNIX is a multi-tasking system. Most people will tell you that this means t hat several tasks or programs run at the same time. However, this is not the complete truth. What happens is that UNIX allows several programs to be in memory at the same time, but they do not all run at the same time. What UNIX does is " v i s i t" on each program in memory and perform a few instructions before visiting on the next program and perform its next f ew instructions. If the number of programs is small and if the computer is fast enough, the user will not notice any delay as his turn comes around so often he thinks he has the whole computer to himself. So on a UNIX computer you could have a person using word processing, another person using accounts and someone else using database all at the same time. All programs are in memory at the same time and the computer cycles

1989 was the 20th anniversary of UN I X . Why is it that it is only now gaining acceptability and becoming such a buzz word? The main reason is that when US legislation released Bell Laboratories, the research wi ng of AT&T, from restrictions imposed because of their monopoly position with telephones and allowed them to license it commercially to other companies they went about marketing it widely, spending huge amounts of money. There was no great secret about what Unix did and how it operated as it was in free use in most of the Amer i can Universities for years. It was a very shrewd move by Bell Labs to license it for a nominal fee to the Amer i can Universities as when it was eventually launched on the market there were thousands of graduates who had used it.

In the period leading up to the release of UNIX, most computer manufacturers were developing their own versions under licence for their own equipment. At the same time Intel were lauching their 8 0 2 86 and 8 0 3 86 micropro- cessors on the market and they wanted an operating system to work on these. Software houses were quick to see the opportunity to develop an operating system for the new cheaper hardware. Micro- soft was one of the first to do this with its version called Xenix. SCO (Santa Cruz Operation) was another company which brought Microsoft's Xenix a stage further and called it SCO Xenix (Microsoft have a large share in SCO). At this stage most computer manufact- urers have their own version of UNIX. This means the " n ew standard operating system" has many different flavours so it is not really a standard at all. IBM has Aix, "At this stage most computer manufacturers have their own version of UN I X . " Digital has Ultrix, SCO has Xenix, Wang has Inix. My own product TOPS legal will run on both MS- DOS and Xenix, but will not run on some of the other versions of Unix. The problem with Unix is that the standard is at a lower level and really interesting features have been added to the standard operating system by the manu-

f ac t u r e r s. This is how t he manufacturers gain their competi- tive edge. So when a software company makes use of one of these features, for example win- dows, in say an accounts program, then the accounts program will only run on that manufacturer's

By Do n a l O ' L o c h l a i n n*

computer. So much for standards. However, life would be very boring if all computers were the same. Prior to the release of Unix, other software houses were developing other operating systems to take advantage of the 8086 and then for the later 8 0 2 86 and 8 0 3 86 microprocessors. The main con- tender here was of course IBM in association with Microsoft with MS-DOS (Microsoft - Disk Op- erating System). This operating system was very quick to establish itself as the standard. Any com- puter manufacturers who develop- ed computers or operating systems which did not conform to the " I B M " s t anda rd perished or changed course. Wang is a notable case here. Even though, in my view, Wang made a far superior com- puter, it was forced in the end to adopt the " I BM Compatibility" tag. The main reason t hat this

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