3 ms·

I also had a bedroom full of electronics in the late 1970s/early 1980s. I certainly wasn't a rich teenager. All the audio gear was given or scrounged. For ex

I also had a bedroom full of electronics in the late 1970s/early 1980s. I certainly wasn't a rich teenager. All the audio gear was given or scrounged. For example, I got given a very good turntable by the father of a friend of my parents for free, when he upgraded his. I didn't even know him, but I'd got a reputation for knowing about electronics, and it was starting to become a little flakey. People would just give me old gear, if it developed an intermittent fault. Old gear was pretty easy for me to fix, but getting it repaired professionally was expensive, and so they replaced things and gave the old ones to me. My mother worked for a company that made cash dispenser (ATM) machines. Every now and then, they'd scrap some old machines, and she'd tip me off. I'd raid the bins behind the company, and carry off whatever I could carry - professional grade power supplies, AC motors, all sorts of electronics that I'd de-solder components from and re-use. We'd also raid the local council dump when the workers weren't watching. A surprising amount of stuff got thrown away that could be fixed and re-sold to friends for a little extra pocket money. Sometime around 1982, aged 15, I saved up and bought a Jupiter Ace computer. It had 3K of RAM, and was programmed in Forth. That summer, I wrote a whole load of games for it, and sold them on cassette through a computer magazine. That paid for the computer several times over. It was never a popular machine, and I think I was one of only about three people selling games for it that summer. Then my school threw out an old teletype. I got permission to take it. There was no printer available for the Jupiter Ace, so I resolved to connect the teletype. Trouble was there wasn't an RS232 interface available for the Ace either. I'd built a TTL-logic parallel board for the Ace from scratch. To get +/- 12V for RS232 I used one of the cash machine 24V smoothed power supplies, used second hand cash machine transistors to switch the power via a parallel port pin, and wrote an RS232 implementation in software in Z80 machine code (hand assembled, as I didn't have an assembler). Eventually it all worked. I must have been the only owner of a Jupiter Ace that had a 1960s printer attached. The Jupiter Ace had one of those crummy rubber keyboards. I'd scavenged enough cash machine keypads, so I desoldered all the keys from them, etched my own circuit board, and made a proper keyboard. That made programming much nicer. Anyway, my parents weren't wealthy, and I certainly wasn't. But you should never underestimate a resourceful teenager.

ams6110 9y ago
About the teletype -- I didn't think they used RS-232, but a current loop (like a telephone) with some early pre-ascii (5-bit?) encoding?
- mhandley 9y ago
  It's been a long time, but I'm fairly sure it was 110 baud RS232, 7 bit ASCII, all upper case. I think it was an ASR 33, or at least I recall it looking like this: https://en.wikipedia.org/wiki/Teletype_Model_33 https://en.wikipedia.org/wiki/Teletype_Model_33 Unfortunately I don't have it any more - my parents threw it out a few years after I left home. Wikipedia certainly implies the ASR 33 used current loop. If I recall correctly, mine had a DB25 connector, which likely indicates RS232, and is probably how I figured out it was RS232 in the first place, as information was hard to come by back then. I do know I used a 24V power supply from a cash machine, using a potential divider to create a +/- 12V signal, which is consistent with the model I had having an RS232 interface. Getting the timing right in software was a lot of trial and error. Edit: this page indicates that RS232 was available as an option on the ASR-33 teletype: http://bytecollector.com/asr_33.htm http://bytecollector.com/asr_33.htm
  - raphlinus 9y ago
    I had one of those too, an ASR 33 with RS-232. I connected it to an Intel SDK-85, which had optional RS-232 stuff on it. Fun times! If I recall, the teletype was sourced from the Green Bank Observatory, which had some really impressive old equipment - racks of hardware with nixie tube displays, all that kind of stuff.
3chelon 9y ago
I totally recognise where you're coming from. I was the same, skip raiding, etc. One Christmas I asked for a present which was a job lot of ex-mainframe PCBs I'd seen advertised in the back of an electronics magazine, Can't remember the cost, but a significant chunk must have been delivery, because it was a fair haul. The boards were just stuffed with 74-series TTL DIP chips, and a lot of red LEDs too. Pretty much every logic chip I used throughout my teenage years came from those boards, and I know for a fact I still have some of the LEDs in my collection - I recognise them by their rather pointed profile, not as cylindrical as modern ones.

ams6110 9y ago

About the teletype -- I didn't think they used RS-232, but a current loop (like a telephone) with some early pre-ascii (5-bit?) encoding?

mhandley 9y ago
It's been a long time, but I'm fairly sure it was 110 baud RS232, 7 bit ASCII, all upper case. I think it was an ASR 33, or at least I recall it looking like this: https://en.wikipedia.org/wiki/Teletype_Model_33 https://en.wikipedia.org/wiki/Teletype_Model_33 Unfortunately I don't have it any more - my parents threw it out a few years after I left home. Wikipedia certainly implies the ASR 33 used current loop. If I recall correctly, mine had a DB25 connector, which likely indicates RS232, and is probably how I figured out it was RS232 in the first place, as information was hard to come by back then. I do know I used a 24V power supply from a cash machine, using a potential divider to create a +/- 12V signal, which is consistent with the model I had having an RS232 interface. Getting the timing right in software was a lot of trial and error. Edit: this page indicates that RS232 was available as an option on the ASR-33 teletype: http://bytecollector.com/asr_33.htm http://bytecollector.com/asr_33.htm
- raphlinus 9y ago
  I had one of those too, an ASR 33 with RS-232. I connected it to an Intel SDK-85, which had optional RS-232 stuff on it. Fun times! If I recall, the teletype was sourced from the Green Bank Observatory, which had some really impressive old equipment - racks of hardware with nixie tube displays, all that kind of stuff.

3chelon 9y ago

I totally recognise where you're coming from. I was the same, skip raiding, etc. One Christmas I asked for a present which was a job lot of ex-mainframe PCBs I'd seen advertised in the back of an electronics magazine, Can't remember the cost, but a significant chunk must have been delivery, because it was a fair haul. The boards were just stuffed with 74-series TTL DIP chips, and a lot of red LEDs too. Pretty much every logic chip I used throughout my teenage years came from those boards, and I know for a fact I still have some of the LEDs in my collection - I recognise them by their rather pointed profile, not as cylindrical as modern ones.