[HN Gopher] The Parallel Port
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The Parallel Port
Author : PreInternet01
Score : 55 points
Date : 2023-01-30 16:45 UTC (6 hours ago)
(HTM) web link (computer.rip)
(TXT) w3m dump (computer.rip)
| PreInternet01 wrote:
| For quite a while, the parallel port was the only external
| high(-ish) speed port on PCs, not only used for printing, but
| also scanning, networking (with a yellow LapLink cable, or, if
| you wanted to get really fancy, a Xircom Pocket Ethernet adapter
| that almost did 10Mbits/s) and even storage (various weird MO
| contraptions, but also a regular hard disk with _almost_ 1MB /s
| read performance...).
|
| The history in the linked article is quite comprehensive, and
| touched on the slightly-incompatible (EPP, ECP) standardization
| efforts for bidirectional use. When USB finally came along, that
| made things a _lot_ more convenient.
| BirAdam wrote:
| Early USB was terrible on both hardware and software support.
| It took a long time for most people to stop using parallel.
| Honestly, the only thing I ever used USB for before the USB2.0
| era was computer mice.
| dave78 wrote:
| This captures the early USB experience pretty well:
|
| https://www.youtube.com/watch?v=IW7Rqwwth84
| dheera wrote:
| I usually ended using the PS/2 adapters because the USB mice
| wouldn't work when you first plugged them in, but they did if
| you used the PS/2 adapter, and then I'd just leave them that
| way.
| h2odragon wrote:
| Early parallel ports were often used for hacked "GPIO"
| applications, they gave you more useful lines than a serial port
| and were often less picky about the voltages.
|
| The "Speech Thing" [1] is the most commercial example I can think
| of, until "laplink" hit.
|
| [1] https://en.wikipedia.org/wiki/Covox_Speech_Thing
| zabzonk wrote:
| i once tried to solder my own parallel printer cable. rs232 i
| could manage, but the parallel cable completely defeated me.
|
| i also had a zip drive that plugged into the parallel port, which
| worked surprisingly well.
| septune wrote:
| Have bricked a windows NT server pluging a printer while the
| machine was ON => kernel panic and NTFS filesystem was corrupted.
| Beware the parallel port is not hot-pluggable :)
| anthk wrote:
| That happened with PS/2 keyboards and mice too.
| _tom_ wrote:
| I hot plugged printers for decodes. No one turned off the
| computer to unplug or plug-in the printer.
| Zardoz84 wrote:
| Then something very weird was doing Windows NT.
|
| I plug/unplug many times a printer, and a ZIP disk unit, to the
| parallel port without issues on Windows 95/98/ME. And more
| recently, a 90's Roland plotter on a 2010's computer that have
| yet a parallel port, running Debian.
| BizarreByte wrote:
| I used to use the parallel port as basically GPIO. It was easy
| and cheap, before microcontrollers were as friendly to use as
| they are now.
|
| I built a lot of custom stuff that way for my PC.
| RobotToaster wrote:
| One of the first (successful) things I built as a teenager was
| a parallel port to TI-82 com cable, so I could install games on
| my calculator.
| zwieback wrote:
| Me too, I also had a board with 8 relays and a centronics
| printer connector. Super easy to switch stuff on and off safely
| back in the day when a PC was a serious investment.
| notRobot wrote:
| Would that still work with USB - Parallel convertors?
| RobotToaster wrote:
| Most seem to very specifically be IEEE 1284 adapters, rather
| than actual hardware parallel ports.
| 0xcde4c3db wrote:
| IEEE 1284 is the relevant standard for "modern" (ECP/EPP)
| parallel ports, but most adapters only provide that
| interface on the printer side, not a general-purpose host-
| side interface to control an IEEE 1284 port.
| mikepavone wrote:
| ECP and EPP are not really useful for GPIO-style use and
| even the simpler modes are not really desirable if the
| adapter is implementing the handshaking in hardware. You
| really just want to be able to manually control all the
| bits. The original parallel port (and later integrated
| ones when set to an appropriate mode in the BIOS) allowed
| this because it was a very simple device and relied on
| software to handle things like toggling the data strobe
| line when a byte was written to the data lines.
| sobkas wrote:
| > Would that still work with USB - Parallel convertors?
|
| I use FTDI 232h based devices to drive 433Mhz transmitters,
| using gpio/bitbang functionality. There are multiple pins
| that can be used for that so theoretical parallel port like
| functionality can be achieved.
| 0xcde4c3db wrote:
| I believe there are some rare adapters that will work with
| custom drivers, but almost all of them I've seen are
| programmed specifically to provide a printer device.
| st_goliath wrote:
| > It was easy and cheap, before microcontrollers were as
| friendly to use as they are now.
|
| I got started with AVR microcontrollers with a DIY parallel
| port ISP adapter: just cut a printer cable in half, solder in 4
| resistors and you were good to go :-)
|
| Then spend a ridiculous amount of time re-learning assembly to
| port the parallel port LED blinking program from DOS to the
| AVR.
|
| Only needing the few scavenged parts and buying just the MCU
| was a _lot_ cheaper than buying the "recommended" adapter
| cable or some eval board, making the whole thing affordable for
| my 13 year old self.
| mikecoles wrote:
| Sound Source and Speech Thing were the weirdest things I recall
| plugging into a parallel port.
|
| https://en.wikipedia.org/wiki/Covox_Speech_Thing
| dheera wrote:
| Yeah I drove stepper motors with the parallel port and some
| FETs all the time.
| usefulcat wrote:
| 20ish years ago I was on a team that was working on the PC
| version of a popular sports game. For the multiplayer mode (2
| players only), the way the game worked both instances had to
| maintain the exact same internal state. For debugging, one of the
| things we used to do was connect two machines together via the
| parallel port and let them play each other for hours. It was
| slow, but still far faster than ethernet because the latency was
| so much lower.
| FullyFunctional wrote:
| Amazingly I was just thinking about the parallel port this
| morning. My first PC (a Toshiba T1850 notebook) only had a serial
| port and a parallel port. Wanting faster network performance
| inspired me to play with PLIP (parallel-port IP). PLIP only works
| in nibble-mode so I played with the bidirectional support and got
| it working. However, I didn't measure much improved performance
| and lost interest. Indeed, later EPP and ECP came around, but at
| the time I couldn't find any documentation. This article fill of
| lot of the gap and has some amazing backstories I never knew,
| very cool.
| mikepavone wrote:
| > Even better, the original IBM PC was capable of a "direction-
| switching" handshake that allowed the peripheral to use the full
| 8 bit data bus to return data. This feature was apparently unused
| and disappeared from subsequent PCs, which is ironic considering
| later events.
|
| I guess this is talking about the XT and AT, but the article kind
| of makes it sound like this simple bidirectional mode was gone
| from all PCs after the 5150 when it in fact came back with the
| PS/2 and remained present on clones long after that. You
| generally needed to set the right parallel port mode in the BIOS,
| but I was using this simple bidirectional mode for communicating
| with a Sega Genesis over its controller port in the mid-2000s.
| alar44 wrote:
| Back in the mid 90s I was teaching myself QBasic and basic
| electronics. Realizing I could combine the two via the parallel
| port on our PC was a magical epiphany that I'll never again
| experience. Being able to "pull" programs into the physical world
| blew my 14 year old mind.
| Zardoz84 wrote:
| I remember my father teaching me about some basic digital
| electronic using the parallel port. How to multiplex and use it
| as GPIO & primitive expansion bus.
|
| Eventually, my father had some board using parallel port for
| stuff. Including a Dobson telescope control board (based on Mel
| Barters designs). I had half-write a program to control it from
| Visual Basic (there was some VB controls that allow to direct
| control of the parallel port). Sadly, the Dobson mount and the
| control board was lost when we move to a new house.
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