My first computer was a kit, a soldering iron and a very patient dad (ZX81, 1981)

Somebody asked in the chat what everyone's first computer was, and I started typing a reply and it got out of hand, so here it is as a proper post. Put the kettle on.

Back in 1981 I was thirteen, and my dad worked shifts at a steelworks in Rotherham. He was not a computer man at all, but he had seen an advert for the Sinclair ZX81 in the paper and worked out, on the back of an envelope, that the kit version was twenty quid cheaper than the built one. £49.95 against £69.95, if memory serves. Twenty quid was a lot of money in our house. So the kit it was, and the deal was that I would build it and he would "supervise", which meant sitting at the kitchen table with a mug of tea telling me to stop rushing.

The first problem was the soldering iron. Dad's iron was a great lump of a thing he used for plumbing, and the first time I went near the board with it I lifted a pad clean off. He looked at it, said nothing, and the next Saturday he came back from town with a little 15 watt Antex. I still have it. It still works.

It took me three evenings. A handful of chips, a lot of empty board, a modulator, a regulator with a heatsink that got hot enough to fry an egg, and a membrane keyboard you had to press like you meant it. We plugged it into the family telly, tuned to somewhere around channel 36, and got... nothing. Grey snow.

I was devastated. Dad went and got Mum's magnifying glass out of her sewing box and went over every joint with me, one at a time, with the desk lamp pulled right down. Forty minutes later he found it: a tiny bridge of solder between two pins on the ROM socket. I would never have seen it. He cleaned it up with the iron and a bit of braid, we plugged it in again, and there it was. The little inverse K cursor in the bottom corner. Mum came in from the other room because she thought somebody had been hurt, the noise I made.

My first program, typed with the one-key keywords (you pressed P for PRINT, it was all printed on the keys):

10 PRINT "PETER IS BRILLIANT"
20 GOTO 10

My sister wrote her own version the next day. I will not tell you what it said about me.

Then came the 16K RAM pack, which plugged into the edge connector at the back and wobbled. If you leant on the table, or breathed too hard, or the bus went past outside, the whole machine crashed and you lost whatever you had typed in for the last two hours. Half the country fixed it with Blu-Tack. We used a folded-up bus ticket and an elastic band. Saving to cassette took about five minutes and worked perhaps two times out of three, and I learnt very early that you write things down on paper as well, which is the oldest backup lesson there is.

The Amiga came years later, in 1988, bought with paper-round money and a loan from Dad that I paid back at a pound a week. That is a story for another day. If you want the proper history rather than mine, Nostalgia Nerd tells it better than I could:

The practical bit, because there is always a practical bit

If you are building a kit today, of any kind, two things Dad taught me without knowing he was teaching me:

• Inspect before you power up. A bright light from the side and a magnifier (a cheap jeweller's loupe is fine) will show you bridges and dry joints your eyes will never catch straight on. Look at every joint. Yes, every one.
• First power-up on a current-limited supply. If you have a bench supply, set the current limit just above what the board should draw and watch the meter. If it slams straight into the limit, switch off and go looking for a short before anything gets hot. Much cheaper than finding out the other way.

Dad is 84 now. Last Christmas I showed him a ZX81 emulator running on my phone and he said "it was better when it wobbled". He is not wrong.

Cheers, Pete