原创 How it used to be: PDP and VAX computers

Note: This "How it used to be" story told by Benny Attar truly takes me back in time. When I started with Cirrus Designs back in 1981, we had a single PDP 11/23 computer that we all shared (we each had a VT100 terminal and a keyboard on our desks). The single hard disc supported 1 megabyte and there was only one directory / folder. I can remember when we got a VAX running the VMS operating system where we each had our own directory trees... it all seemed so revolutionary back then (grin).

After completing my studies in a technical college in 1984, I joined the Services – never mind what service, that's classified – and was put in charge of the computer room. In those days, all the computers were in a central location, with restricted access, climate control, raised floors, and servants to look after them. Ordinary mortals had computer terminals and printers connected to the computer room through RS232 lines at 9600 baud (the longer lines wouldn't work beyond 4800 baud – for some lines we even had current loop converters).

Almost all our equipment came from DEC – we had a couple of PDP11/70's ( I remember being told they cost $120,000 each), a PDP11/44, and a VAX 730. The VAX 750's came later, then the 8300 and 8500 series, then things got smaller with the micro-VAX 3500, 3200 and 3100 computers in the early 90's.

The end users were given VT100 and VT102 monochrome monitors, and mighty heavy to carry around they were. The VT100 had a bug in the firmware, if you hit a certain sequence in setup – esc-shift-3 then q, I think it was – you would get a screech from the keyboard speaker. One of our programmers wrote a program that mimicked the terminals' setup screen. Run the program, and apparently you would be locked for eternity in setup.

Data storage was on a bank of 6 removable disc drives, each the size of a washing machine and holding 67 megabytes. Of course, we had the mandatory reel-to-reel tapes and 8 inch floppies. I was in charge of a small team of "computer operators" – there did exist such a job description once – who ran the daily backups, changed printer ribbons (the ribbons were packed as mobius loops so they'd be used on both sides), distributed printer paper (fanfold with sprocket holes) and taught new personnel how to operate a terminal ("Press setup-0 to reset the terminal...). One of my young operators went on to complete 2 engineering degrees and a doctorate in computer science, and is now a senior research scientist in the field.

We also had some Evans and Sutherland graphics computers for one of the projects involving tactical map displays. The controllers were housed in their own cabinets, with backplanes full of PCB's – mostly TTL standard logic and some 2901 bit-slice processors. We had just 2 colour displays, giant table sized cabinets with 21 inch displays and huge temperamental power supplies. They needed constant adjustment to keep the red, green and blue beams aligned, they needed degaussing with an external degauss ring, and they kept blowing transistors in the deflection amplifiers. The black and white monitors never gave any trouble, though. Of course in those days all this hardware came with shelves of ring binders full of schematics, maintenance instructions, and software descriptions. Other peripherals included XY magnetic tablets (before the days of computer mice) and pen-plotters for printing maps.

When the PDP11/70's were retired, I took a screwdriver and dismantled the front panel of one of them, with all the address/data entry keys and register lights. A colleague took the panel from the second one. I still have it, nearly 25 years after the last program ran.

When the PC revolution came and computing was no longer centralized, the job wasn't interesting anymore, so I transferred to a job working with automatic test equipment, and found myself with a Teradyne L210 tester and a few VAX stations. When I retired from the job, I think I was one of last people in the organisation who still worked with the VAX/VMS operating system.