5 ms·

This remind myself the good old 8bit days of using a cross-over RS232 cable to send a file from one computer to another. even at 30bps, it was much more reliabl

This remind myself the good old 8bit days of using a cross-over RS232 cable to send a file from one computer to another. even at 30bps, it was much more reliable than write my data to a cassette tape on one computer and then reading on the other.

ErroneousBosh 17d ago
I have plugged two ZX Spectrums together and done LOAD "" on one and SAVE "THING" on the other to transfer data. If you get away from BASIC commands and copy the tape routines up into RAM you can mess with the timing values, and with care you can get it from an average of 1800bps up to around IIRC 12000bps before things really fall apart. Probably with better interfacing you'd get even faster. With more conservative values, this is how "speedloaders" worked. In the late 80s or early 90s one publisher released games on CD where it would load in the loader at normal rate then ramp up to some unholy speed that CD had the bandwidth and stability for but tape did not.
hdgvhicv 17d ago
232 crossover was still going in the PC era with laplink. Parallel was an option too if I remember. Used to play Duke Nukem 3D over a null modem serial cable. In the days of the spectrum where you loaded via an analog audio input from a tape, and saved via the output, you could move from one to another in the same way, skipping the tape. Apparently this was about 1kbit per second.
inigyou 17d ago
But did you ever plug one computer's cassette out directly to another computer's cassette in?
- yitchelle 17d ago
  Not possible on my system. It was only computer<->cassette connection.
  - inigyou 16d ago
    You weren't thinking like a hacker.
thenthenthen 17d ago
Yeah! Werent these also called NULL-modem cables?
- myself248 17d ago
  Because if you had modems between the computers, you used straight-through RS232 cables -- the PC would have its Tx/Rx pins according to DTE standard, and the modem would have its Tx/Rx pins according to DCE standard. The modems did the "swap" themselves by choosing tones at dial/answer/negotiate time, then the other modem-to-terminal link was likewise straight-through. But if you were connecting two terminals directly with no modems, thus the modem was "null", you needed the cable to do the signal swap instead. Hence the name!
  - wildzzz 15d ago
    I realized this the other day: it's funny that back in those days, you didn't have two computers (or teletypes) close enough together for them to talk to one another just through serial data. Why would two teletypes need to be in the same room? Just use a typewriter! And furthermore, how could you possibly fit two computers in the same room?! You probably had a phone line (or a radio set) handy so two modems would sit between the two devices and handle the long distance portion of the conversation. The null modem cable kinda developed as a thing once it actually made sense to have two computers in the same room that needed to share data faster than you could just enter it yourself.

ErroneousBosh 17d ago

I have plugged two ZX Spectrums together and done LOAD "" on one and SAVE "THING" on the other to transfer data. If you get away from BASIC commands and copy the tape routines up into RAM you can mess with the timing values, and with care you can get it from an average of 1800bps up to around IIRC 12000bps before things really fall apart. Probably with better interfacing you'd get even faster. With more conservative values, this is how "speedloaders" worked. In the late 80s or early 90s one publisher released games on CD where it would load in the loader at normal rate then ramp up to some unholy speed that CD had the bandwidth and stability for but tape did not.

hdgvhicv 17d ago

232 crossover was still going in the PC era with laplink. Parallel was an option too if I remember. Used to play Duke Nukem 3D over a null modem serial cable. In the days of the spectrum where you loaded via an analog audio input from a tape, and saved via the output, you could move from one to another in the same way, skipping the tape. Apparently this was about 1kbit per second.

inigyou 17d ago

But did you ever plug one computer's cassette out directly to another computer's cassette in?

yitchelle 17d ago
Not possible on my system. It was only computer<->cassette connection.
- inigyou 16d ago
  You weren't thinking like a hacker.

thenthenthen 17d ago

Yeah! Werent these also called NULL-modem cables?

myself248 17d ago
Because if you had modems between the computers, you used straight-through RS232 cables -- the PC would have its Tx/Rx pins according to DTE standard, and the modem would have its Tx/Rx pins according to DCE standard. The modems did the "swap" themselves by choosing tones at dial/answer/negotiate time, then the other modem-to-terminal link was likewise straight-through. But if you were connecting two terminals directly with no modems, thus the modem was "null", you needed the cable to do the signal swap instead. Hence the name!
- wildzzz 15d ago
  I realized this the other day: it's funny that back in those days, you didn't have two computers (or teletypes) close enough together for them to talk to one another just through serial data. Why would two teletypes need to be in the same room? Just use a typewriter! And furthermore, how could you possibly fit two computers in the same room?! You probably had a phone line (or a radio set) handy so two modems would sit between the two devices and handle the long distance portion of the conversation. The null modem cable kinda developed as a thing once it actually made sense to have two computers in the same room that needed to share data faster than you could just enter it yourself.