Sunday, 3 April 2022

Emulating the past

“It’s no use going back to who I was yesterday, because I was a different person then”
Lewis Carroll

For so long, now, it's very fashionable to go back to how things were, that retro is almost passé.

It's computing that makes it all possible, of course. Computers today are so powerful that they can emulate older computers even faster than full speed.

Even in my lifetime, new computers became so fast that they weren't slow enough to properly run some of the older programs that they were supposedly compatible with. That's always fun telling the user "It's because your computer is so powerful it crashed the program". It's quite something to watch them dilute their own frustration with a mingling of pride and awe.

My history with computers started as a pre-teenage child when I traded a pair of opera glasses (that I had got from a friend whose dad ran a waste processing business) with a school teacher, to get an old electric school bell. I used to wake up at night from realistic dreams of the electric shocks that I inflicted on myself during the day.

Around the same time, my dad brought a bunch of old Bakelite telephones home from where he worked. I'm not sure what he did with them, but when he'd finished, I knew enough to fix them up with my old train transformer and make some kind of an intercom system (incurably suffused with a 50hz hum loud enough to give you a headache).

It went on from there. What pocket money I didn't spend on sweets I'd spend on the Maplin Electronics catalog and look at all the things I could build, and all the things I could build them with, if only I wouldn't spend all my money on sweets.

And that was the problem. Apart from the odd FM transmitter, I didn't build very much because electronics is an expensive hobby - all those parts to buy. I used to get by filing components from old transistor radio circuit boards before I was given leave to use the antique soldering iron. I still have a scar on my wrist from that!

But one day as I was walking home from school along the main road, that we all traveled, I heard some crazy talk, and that made all the difference.

My brother was talking to a friend about a computer program that he had written at computer club, which made a man walk across the screen, getting lower and lower, and leaving some dots behind him. It sounded fantastic, but yet his ideas intrigued to me.

I don't know what I had been doing instead of going to the computer club, but the very next time I did go to the computer club and asked the computer teacher:

Please write me a program that makes a man walk across the screen getting lower and lower and tell me how it does what it does.

Even now I am as impressed by my ability to synthesize that request as I am of my ability to understand the program.

The program is something like this (Try it on the Beeb Emulator at https://bbc.godbolt.org/):
10 CLS
20 FOR Y=0 T0 25
30 FOR X=0 T0 40
40 PRINT TAB(X,Y) "*";
50 PRINT TAB(X,Y);
60 A$=INKEY$(10)
70 PRINT TAB(X,Y) " ";
80 NEXT X
90 NEXT Y
The teacher explained how it worked but it was pretty obvious. He was a kind and good teacher, so rather than answer my questions all night, he gave me the user programming guide (for those were the days when the users did the programming).


One misspent youth later, including the notable event of being dragged out of the computer room by the invigilator so that I could sit what was left of my french exam, I had written the following computer software:
  1. The school email program (BBC Micro, on the eNet network system)
  2. Decode morse code (including punctuation) (Sinclair ZX81)
  3. Various programming tools (music output, read-data-&-restore) (Sinclair ZX81)
  4. Database (Amstrad CPC6128) where I learned that adults will answer personal questions posed by a child if a computer is used.
  5. 3-player personal computer implementation of electronic game Detective Shoestring originally by Grandstand, which involved a cardboard separator on the screen, and added a helpful detectives dog as the third player. (Amstrad CPC6128)
  6. Much much more, and I also learned the futility of adding "-on-a-computer" to various other specialist tasks of the time. My attempt at scenery design on a BBC micro was doomed.
I think I only paid for 1 computer, my ZX81, and the seller gave me many a sleepless Friday night as he repeatedly forgot to bring it on Saturday each week. Christmas eve excitement was nothing to getting my first computer. My Dad then bought me a portable TV to stop me hogging the one in the front room.

Through kindness and good fortune I was lent/borrowed/given the following: 
  • ZX Spectrum 48K
  • Amstrad CPC6128
  • TRS80 II with dual disk drive
  • 80286 with 2MB RAM and Hercules Graphics Card
  • 397SX16 with 4MB
After which I was able to buy a 386DX40 motherboard and 4MB RAM with Crystal sound card, and a second hand 540MB hard disk for £40

Such glorious memories.

And now -- the computers of the past return in the form of an emulator. All of them. Most of them will even run in a web browser.

I've installed some of them, but mostly I just look and stare in a daze.

What do I want to make it do? 

Nothing. I did it all already. 

I can't go back to my childhood, I'm not a child anymore.

I seek not to follow in my footsteps of old, I attained those things I sought.

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