Near the beginning - Reminiscences of a half century in IT 17th August 2015
Near the beginning – Reminiscences of a half century in IT
9th June 2015
So when was the beginning?
Charles Babbage? Certainly the founding father of IT. (No, I’m not that old)
Alan Turing? Very much in the news. A life cut short that could have moved us much further forward much faster.
Tim Berners-Lee? Can any teenager imagine life without the World Wide Web? (I am older than him).
Next year I will celebrate 50 years in IT. So I reckon I am allowed to do some reminiscing and get misty eyed over a VAX, ICT, 360 or PDP. Or even a punched card. Actually it was called DP when I started – Data Processing, or Electronic Data Processing to distinguish it from Mechanical Data Processing. But then I guess MDP is where I really started. I was going to call this article “Face down, 9 edge leading” but it would take a whole article just to explain that. (Perhaps I will tackle that and its MDP heritage in a future blurb).
So in 1966 the parts division of a major British motor manufacturer took delivery of an ICT 1500. ICT – International Computers and Tabulators was an English company that rivalled International Business Machines – American IBM. ICT became ICL (dropping the Tabulators and adding Limited) but both ICL and the motor manufacturer are long gone. Anyway I was in the 3rd and final year of a commercial apprenticeship with the aforementioned motor company. (Rootes Group, for the record, was Humber, Hillman, Singer, Sunbeam and Talbot cars plus Commer and Karrier trucks). The parts division stocked over 100,000 different parts and handled 5,000 order lines per day from their dealers. These were processed by a large punched card Hollerith system that involved at least 50 people. The ICT computer was so big it had a whole brand new air-conditioned building to itself and its workers. Thinking that this looked more interesting than selling or servicing cars I quickly got my training schedule changed to be part of this pioneering team.
The project was to “computerise” the stock control and order processing from the Hollerith setup. I don’t intend to bore you with details of that. What I thought you may find interesting was the equipment and language we were using.
The Processor and Memory. This was housed in a multi-doored cabinet about 15 feet long, 6 foot 6 inches high and 18 inches deep. (Sorry you metric people, but it was the 1960’s. Try 4.5 x 2 x 0.5 metres.) Ours had at least 2 extra bays to the left of the console in the picture above. The memory had 20,000 6 bit bytes. No not 20 x 1024 but 20,000. This was ferrite core memory. Each bit has a magnetic toroid or ring which can be set to one or zero by passing electricity through the correct wire. So 20,000 time 6 bits meant 120,000 ferrite rings with wires through them. This alone was about 18 inches cubed and obviously got quite hot. Unlike later semi-conductor memory this was not volatile when the current was switched off. It “remembered” what all the bits were set to, so when the machine was assembled the engineer pressed Go and it started running the memory check program that it had been running in the factory before it was disassembled and shipped. Much the same as a USB memory stick but a bit larger.
The whole Processor had a cycle time of 4.7 milliseconds say just over 200 cycles per second. Your average tablet today can do 15 with 9 zeros after it in one second. No wonder I feel so tired some days. Also it did not have a full arithmetic unit which even the humble Raspberry Pi has. This means that it could only add and subtract. So to multiply you had to personally program a loop of repeated additions. And to divide multiple subtractions. Each one taking several processor cycles. Don’t forget this is pre-decimalisation, so we had to do calculations in pounds, shillings and pence. Nightmare!! When we eventually got the export invoicing program running the printing would actually pause between each line whilst the calculations were done. This included something mysterious called “overriding discount”. Not sure if it would be allowed these days but it was certainly good for Harrods and Bond Street when the overseas owners came to London.
The Console. As you can see from the picture, this had a nice set of flashing lights and buttons. The bank of white buttons on the right were used to enter individual machine instructions such as
Symbol fill all memory with spaces. We did this between each job
Read a card into memory location 600 then transfer control to that instruction
That was how we got the Bootstrap in. The bootstrap was a set 13 x 80-column cards. These were placed on the front of each program. The programs to start with were in a deck of cards one assembler instruction per card. Some programs had well over a 1,000 of them. If you dropped them you were really stuffed. Had to gang punch a new set from magnetic tape and that could set you back 20 minutes or more. The gang punch was very noisy and the Fat Controller could hear it and would come in to see what was going on. Trouble at ’mill.
The two banks of darker buttons on the left were actually red alarm lights with acronym letters on. The processor would stop with one or more of these lit up and we operators had to work out what was wrong. One frequent combination was MAPE MRPE DRPE, affectionately known as three fingers. I’ve still got the manuals somewhere if anyone is nerdy enough to want chapter and verse but it was all parity errors when reading data into or out of the memory.
You see, they were not very reliable. They hiccupped several times a day. And it could take quite a while to find the correct dose of milk of magnesia to settle it down and coax it back to work. But we had help. We had an engineer on site two shifts out of three!! Imagine a “Tech Guy” from PC World sitting there in your lounge playing on his tablet on the off chance your laptop threw a wobbly. They even had their own office with a door directly into the computer room. Full of spares it was. Never the right ones of course, but fascinating anyway. Don’t forget the circuit boards were still full of transistors, capacitors etc. No integrated circuits or chips back then lad. We was lucky we didn’t ‘ave all them valves like they do at Bletchley Park. Or in the 555 Hollerith calculator we were slowly replacing. Mind you we had a gradely time holding the soldering iron for the engineer when he eventually found which one of the blighters had gone phut and had to be replaced. Put us hours behind it did. And all them warehouse staff hanging around waiting for their picking dockets to rattle off the printer. The Fat Controller was having apoplexy. But just like today, repairing something takes as long as it takes. Except today we just throw it away and use a new one.
Oh well, that’s enough for today. Just as John Ebdon used to say on the Home Service – If you have been, thanks for listening.
Ferrite Core Memory