In the 80s and 90s, PCs had something called a printer port. It was a place you could connect to a printer and they would communicate back and forth. When programming in C you could access that port. Each pin of the connector had a well defined job, but....... - ThreadSky

zim2918.bsky.social • 33 days ago

In the 80s and 90s, PCs had something called a printer port. It was a place you could connect to a printer and they would communicate back and forth. When programming in C you could access that port. Each pin of the connector had a well defined job,

but.......

Comments

bcarl314.bsky.social•33 days ago

I still have a LX200 Meade scope that's hooked up to a serial port with an adapter to my rasp pi that I programmed a web UI using PHP and Apache that pipes to a QBasic interpreter to send commands.

prima13.bsky.social•33 days ago

Wow that’s quite the pipeline.

bcarl314.bsky.social•33 days ago

What I think is cool is that the programming manual has a y2k bug in it.

sojournermemoirs.bsky.social•33 days ago

Ah, the Centronics interface! I remember it well.

zim2918.bsky.social•33 days ago

If you ignored what the port was supposed to be used for, you could easily build machines that could be controlled by the PC, send back data to the PC, and even use the port to connect multiple PCs together.

hph.pw•33 days ago

Ah yes, I remember soldering together a Covox Speech Thing clone

hph.pw•33 days ago

Surprisingly not the most basic of my "electronic" projects. Another was a red LED with the top chopped off and glued to a cut-off TOSLINK cable. The LED was soldered to a jack plug that went into a later SoundBlaster's coax port. I used it to record music to minidisc.

zim2918.bsky.social•33 days ago

I remember building the electroniccs, attaching them into the printer port and writing the software to collect reaction time data for a perceptual psychology experiment in about a day.

I miss the printer port

simondo65.bsky.social•33 days ago

I used one for driving stepper motors on a 3 axis robot.

I remember too various peripherals (including tape and ZIPdrives) using the printer port when they needed a higher throughput than the serial port.

snepperstepping.bsky.social•33 days ago

Its stuff like this that make modern computers SOOOOOO FUCKING BORING no matter how fast the processor goes or how many polygons the graphics card can render or whatever. I crave tinkering and breaking the rules for better user experience and for fun!

joocifer.bsky.social•33 days ago

raspberry pi!

frwessling.bsky.social•33 days ago

GPIO pins can be used for much fun

snepperstepping.bsky.social•33 days ago

I don't want a goddamn egg i want specific systems that already exist because they meet the needs i have better than i can articulate in the process required for the goddamn egg stuff to have a result.

zim2918.bsky.social•33 days ago

For another psych experiment, I had to create a display that had gray sinusoidal stripes that had to move imperceptively slowly across the screen. I did it by flipping the color table creating sub-pixel smooth motion across the screen.

hamstorau.bsky.social•32 days ago

3rd year Elec Eng project was to 'network' 4 computers together using their printer ports.

hamstorau.bsky.social•32 days ago

PS: Circa '94/95

zim2918.bsky.social•32 days ago

very cool

tootootootsrn.bsky.social•33 days ago

RS 232💪🏻

chwarae.bsky.social•33 days ago

tidy. i used power transistors to turn half the printer port into a stepper motor driver, the other half into a data bus, and automated a previously manual optical transmission spectrometer.
yes its easier these days, but i miss burning my fingertips in the solder buckets of a DB25.

zim2918.bsky.social•33 days ago

very cool

musselwhite.dev•33 days ago

Ahh, that brings back memories. That's what I love about the Raspberry Pi. You can program it in just about every language, including Python, C, and Rust, to do what you've described and more without the risk of frying your main computer. There's even an open-hardware parallel port HAT for it.

brianhill53703.bsky.social•33 days ago

lpt0 on fire

zim2918.bsky.social•33 days ago

Looks a little bit like a cybertruck

zelwinters1981.bsky.social•32 days ago

More useful than a CyberTruck.

josemirm.bsky.social•33 days ago

At least modern industrial mini PCs has GPIO/UART ports, even of they have a Intel or AMD CPU, so if someone needed something beefier than a RPi, they can have it.

Outside that, I'm really happy with the variety of small SBCs we have at the moment to cover those tinkering urges :-)

matt-nicholson.bsky.social•32 days ago

If you could tell this to my current printer, that would be much appreciated. It nor knows, nor wants to know how to print.

vim-for-life.bsky.social•33 days ago

If I remember correctly, this wasn't a "printer" port. It was a parallel port. You could send 8 bits at the same time, as opposed to the serial port which could send only a single bit. Dad is a chemist, and used that port for all sorts of instruments, not just to desecrate flat dead trees.

zim2918.bsky.social•33 days ago

You had ground, power, incoming bits, outgoing bits, and bidirectional bits. It was a lot of fun to mess with

objdart.bsky.social•33 days ago

I used to plug printers into those ports!

norzola.bsky.social•33 days ago

We used the port to connect PCs and play Doom Deathmatch! Was it the bespoke autoexec.bat file I ran to prevent windows from running? (to save capacity for the game) 🤔 It's been a while...

simondo65.bsky.social•33 days ago

In a slightly unusual configuration, but still used as a printer port. My friend had an ASR33 teletype, but they came with current loop serial ports, and our computers at the time didn’t have serial ports, but they did have parallel printer ports…

simondo65.bsky.social•33 days ago

… but the teletype had a punched tape reader that used microswitches to read the tape holes, and could print from that. We wired reed relays across the microswitches and built a relay driver for the printer port, and rewrote the printer driver to make it slow enough for the teletype.

simondo65.bsky.social•33 days ago

(incidentally this was in the days before the PC, the computer was a 6502 based Acorn Atom)

hikercat.bsky.social•33 days ago

Yes, if I remember correctly, you could connect machines to it as well as the first robotic.

timtripp.net•32 days ago

I also had an Iomega ZIP drive that connected via the parallel port. And you plugged the printer into the ZIP drive. Of course, you couldn’t print and use the drive at the same time.

Can’t remember the brand but I also had a parallel port tape drive for backup purposes. A whole gig on a tape.

discovery-process.bsky.social•33 days ago

VGA connectors have a bidirectional I2C line, if you enjoy hacking.

traepalmer.bsky.social•33 days ago

I remember most of my printers back then using the "Centronics" parallel port.

sirbustergoodoup.bsky.social•33 days ago

Now, everything g is on WiFi, and all is screwed up. My old printer/ scanner is a dinosaur in today's world, hardly works anymore.

ldo17.bsky.social•32 days ago

Apple never had one of these.

I recall they were even used for odd things like CD-ROM interfaces (because Microsoft compatibles kept having chronic trouble with SCSI). But access was so CPU-intensive that performance was terrible.

columbia57.bsky.social•33 days ago

Lee: I am not computer savvy and finally gave up wonderful 24-pin printer because couldn’t figure out how to connect to modern laptop. It was fast, quiet, output looked as good as laser, paper cheaper, no jams. You’ve made me sad! If I could get it back, I would even just to look at it

letspartytilldawn.bsky.social•33 days ago

LapLink FTW!

brooklynkid53bskys.bsky.social•33 days ago

iirc, a lot of people like you were big fans of the Amiga because it had a lot of built in communication stuff ?

zim2918.bsky.social•33 days ago

It was an awesome machine. Cheap too. They used a bunch of Amigas in parallel to do the graphics for the original Battlestar Gallactica

dakhwon.bsky.social•33 days ago

I don't think Amigas were around in the 70s. I know Babylon 5 used Amigas for the graphics.

zim2918.bsky.social•33 days ago

yes. you are right. I get my B's mixed up

psvrh.bsky.social•33 days ago

The only issue I recall is that if you did this a lot, and your machine was slow, it was a big performance hit.

For controlling devices like CNC equipment is was fine. For hard drives it suuuucked

chrisdicko.bsky.social•33 days ago

You could also prevent folks from pressing Prt Scr to dump the screen contents by setting Int 5 high. A trick I used for awhile. Loved C, still do.

mariusstuparu.com•33 days ago

To prove that printers would not repond to commands, no matter the port you use…

rockney.bsky.social•33 days ago

I once designed the electronics and wrote the assembly language driver for a software license "dongle" that used that port. We encased it in black epoxy.

tr00st.co.uk•33 days ago

The Covox Speech Thing comes to mind - mildly interesting solution to an old problem.
https://en.m.wikipedia.org/wiki/Covox_Speech_Thing

primarylupine.bsky.social•32 days ago

Found a schematic included with a DOS .mod player for a simple D/A convertor one could build with a pile of resistors that worked just like the Sound Thing.

primarylupine.bsky.social•32 days ago

Confused the shit outta my PC repair class teacher when I plugged a haphazard web of them soldered to half a printer cable into a machine, and sound came out of it when connected to some desktop speakers.

primarylupine.bsky.social•32 days ago

@scalibq.bsky.social's posted them here:

https://scalibq.wordpress.com/2017/11/28/the-covox-years/

ledow2.bsky.social•33 days ago

I used to use a DOS packet driver that used daisychained serial and/or parallel ports between the computers to pretend to be a network. Used to play Doom via IPX and send files over it. Slow, but worked great.

zim2918.bsky.social•33 days ago

For me, there is a little bit of joy when I use technology in a way it was not intended. I miss those simpler days when the software and hardware were not so protected and a little raw

bcarl314.bsky.social•33 days ago

I feel like RaspberryPI opens this up again.

eridanian.bsky.social•33 days ago

I agree. In high school many years ago, we had an IBM 1130 for data processing. It didn’t have any sort of clock, so I programmed the attached 1132 printer to act as a RTC by capturing the per-character 11 msec print wheel interrupt to keep track of time. Great fun.

thebigbadme.bsky.social•33 days ago

now *that* is a master class hack.

tedfromtheinternet.bsky.social•33 days ago

I remember when I had an old Compaq PC running Windows95/98/ME and I never had to troubleshoot printer issues because of the simple printer port. It was purple, and it worked.

Last month I had to install 2 apps to get my shitty printer to just be seen by Win11 on wifi.

variabel.no•33 days ago

For my BFA finals I took an old dot matrix printer with a tractor feed and hooked it up to a raspberry pi. I wrote a simple program that sat on twitter collecting selfies, converted the images to black and white and then printed out an ASCII version. This is now over ten years ago which seems wild.

chuckreis.bsky.social•33 days ago

You could access that from anything; I used it for all kinds of interfacing with BASIC, C, and Pascal. The parallel port was a swiss army knife back in the day.

zelwinters1981.bsky.social•32 days ago

Confirm, could write to lpt1 from QuickBasic.

armand-79th.bsky.social•32 days ago

I knew I still had one somewhere... 😅

rsol.ca•33 days ago

Laplink!

smashcat.org•33 days ago

Yeah, I mean we kind of do the same with USB now, which also has much faster data transfer rates - I've used custom devices for anything from slow serial-driven tech to custom event installations capturing a desktop at 60fps, squirt it down USB to redisplay on LED matrixes OR mechanical devices :)

smashcat.org•33 days ago

FTDI do some custom USB 2.0 high-speed chips for example, that can create 4 endpoints, each of which can be set up as SPI, i2C, UART, parallel or a custom bit-banger. 😁

illuminaughti.bsky.social•33 days ago

So you were bit banging before bit banging was a thing?

simondo65.bsky.social•33 days ago

Bit banging has been around for ages. The sound on my first 1970s computer was just a single bit on an output port connected to a loudspeaker that the CPU toggled to make a noise. The cassette port that it used for saving programs was a single bit too that the CPU bit banged CUTS 300 baud data to.

illuminaughti.bsky.social•33 days ago

Way before my time

viperdrake.bsky.social•33 days ago

I wonder if that's possible with usb -C

zim2918.bsky.social•33 days ago

If you cut both ends off

talvimusic.bsky.social•33 days ago

Not really. There's layers and layers of protocols and drivers needed to communicate over USB. You need to implement a lot of stuff to use it on low level compared to a few lines of assembly language to interface with the printer port.

jaycee1980.bsky.social•33 days ago

It's not as hard as you think - libusb can take care of a lot of it

talvimusic.bsky.social•33 days ago

Sure, there are libraries. But building your own USB hardware is not just a few resistors and wires and it's still a lot more complicated to get something done. One of the greatest and most fun things about working with old stuff is that you can get something lowlevel running in 20 lines of asm.

zim2918.bsky.social•33 days ago

Exactly

jaycee1980.bsky.social•33 days ago

If you want it that simple, then the modern day equivalent is an Arduino. Plenty of options for bitbanging IO with those, and it's programmed in C.

olenatheshroomlady.bsky.social•33 days ago

In still have laptop with CD drive. And CDs too

zim2918.bsky.social•33 days ago

Just bought a machine that can play vinyl records, cassette tapes, CD's, the radio, and also accepts bluetooth. If only it could play those eight tracks I have laying about

olenatheshroomlady.bsky.social•33 days ago

Wow, neat!

zhangschmidt.bsky.social•33 days ago

I've been wondering if the best way to digitize photo slides mightn't be to buy a slide projector and take photographs

oldmangatling.bsky.social•33 days ago

Playing "multiplayer" games like DOOM through the LPT port was a thing too. (Direct Cable Connection)

dowhiletrue.bsky.social•33 days ago

I connected the pins to CMOS latches which drove an array of solid state relays. The software I wrote in C created a Christmas time light display... Those days are gone forever!

jaycee1980.bsky.social•33 days ago

not really.. you just wouldnt use a PC any more, youd use something like an Arduino

dowhiletrue.bsky.social•33 days ago

Yes, our Halloween is ran with Arduino :-)

zim2918.bsky.social•33 days ago

The thing about having a parallel port built into every PC is that I could build a machine to collect data, make it work with my PC through the port use the software on the PC to analyze the data. Unhook it and carry it to another lab, borrow a PC, and have it running within minutes

jaycee1980.bsky.social•33 days ago

You could still use the Arduino for that - they have serial via the USB port. Send the data you want to collect over that to the PC.

unbufferedint.bsky.social•32 days ago

Back in the 2000, laptops had a special port that was specifically designed to rip laptops out of the hands of unsuspecting high school students when they turned their robot on.

taurking.bsky.social•33 days ago

I was aware this used to be a thing, but was not aware it ever stopped being one. Strange

dragostech.bsky.social•33 days ago

They still do software controllable pins, but it's called GPIO lines now. They even have prominent easy to wire connectors if you use Raspis or similar form factors.

pathar.tl•33 days ago

I made a MAME cabinet in 2010 and I needed a way to connect the buttons to a PC. I ended up finding a driver that allows you to connect a SNES controller to the parallel port. It still works today!

sequencedlife.bsky.social•33 days ago

Most new (ish) pc motherboards still have printer, COM, and sometimes even PS/2 ports!

cluonflux.com•33 days ago

Parallel port sound cards were a hilarious 8-bit DAC, the CPU would have to bitbang every sample, and the resistors needed to be very precise

zim2918.bsky.social•33 days ago

The trick is that you could use the output lines of the printer port as an analog signal followed by a low pass filter into a speaker.

sarexpert.bsky.social•32 days ago

Centronics cables were only able to go 25 ft, cost a lot, didn't like UFT-8 or graphics. When USB came around Centronics and 25 pin connectors were dinosaurs.

zim2918.bsky.social•32 days ago

I wouldn’t use the cable. Just the port. This would let me use a common PC as a microcontroller.

lillianames.bsky.social•33 days ago

I fell in love with the GPIO of the raspberry in 2016

epoz.org•33 days ago

Oh come on, we are _so_ much better off nowadays than back then.

Yes, I am a grey beard whio did my fair share of bit-banging back then over parallel and serial ports, but we are blessed with opportunities for linking up stuff today that we could not dream of then.

zim2918.bsky.social•33 days ago

I am a luddite. I believe that the complexity at the interface only benefits our corporate overlords and doesn't necessarily improve our standard of living

epoz.org•33 days ago

Totally, I hear you.

But I fear we have to blame the collective software developers who chose to get stuff out the door as soon as possible, in stead of choosing to make stuff simple.

The biggest challenge nowadays is figuring out what to ignore. :-(

coolingjets.bsky.social•33 days ago

I still have a laptop with a printer port. Modern printers use USB. Get a RasbrryPi or something similar if you want to experiment.

zim2918.bsky.social•33 days ago

Microcontrollers are fun to mess around with and I grew up using Linux, but there was something fun about stepping around the “rules” that was exciting

coolingjets.bsky.social•33 days ago

That's why I keep a few old laptops around, they have some useful hardware ports. Modern laptops don't even seem to have enough USB ports, unless you have an external hub.

creatorbri.bsky.social•33 days ago

This reminds me of the days when printers didn't try to sign you up for a lifetime subscription for ink cartridges by pestering you about it with ads masquerading as low ink warnings every time you just wanted to print something..

slimdude.ca•33 days ago

Epson eco tank printers don’t use cartridges.

creatorbri.bsky.social•33 days ago

I feel like all printers have gotten so much worse over the past 10-15 years, but I'd give Epson another go. Last one wasn't bad.

Since we're talking retro computing, btw, my first PC was an Epson QX-10 with a massive dot matrix printer that sounded like a giant malfunctioning death laser.

slimdude.ca•33 days ago

Ahhh yes, dot matrix. The days when we had to code our own printer specific code. Fun times.

davegodin.bsky.social•33 days ago

And fanfold tractor feed paper. What fun tearing off the perforated edges. Printer stand with a slot to feed the paper from a box on the floor.
I had a soundproofing box for my printer, which was of questionable value. So bulky.

creatorbri.bsky.social•32 days ago

Yes exactly!!

eyeballologist.bsky.social•33 days ago

My personal favorite: when one of the colors is low but I’m printing in black only. But it won’t print because one of the colors is low. Like seriously?!

tawdle.bsky.social•32 days ago

I had (emphasis on past tense) a printer/scanner combo that wouldn’t allow me to *scan* when one of the ink cartridges was low. That was the last straw.

Paying more up front for a printer with easily/cheaply refillable tanks really improves the economic model of printer ownership.

subflyer.bsky.social•32 days ago

Government mandated identification codes containing model, serial number etc. need color inks. Usually yellow dots that you don’t see on your printouts.

https://en.wikipedia.org/wiki/Printer_tracking_dots

zim2918.bsky.social•32 days ago

Are the yellow dots there in copy machines?

subflyer.bsky.social•32 days ago

I believe in color copy machines, yes. And quite a few detect currency and then print out just a black rectangle instead of a copy.

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