Parport and BOB combination recommendations?

27 May 2023 14:17 #272265 by Halbear

Total newbie here, I've read through some topics but am a little (read: a lot) fuzzy on things and hoping to get some guidance. 

First, the FAQ section mentions that parallel ports are an inexpensive way to get IOs; I was originally under the impression that IOs were the jurisdiction of breakout boards, and connectivity largely depended on both being present and connected. 

Some of the threads recommend specific Mesa BOBs, but Mesa seems to be sold out of the recommended ones (which I'm assuming have had long successful use and therefore community documentation).

Do the two need to be matched in any way, and if so, can anyone recommend a combination? Im running an older HP Pavilion with a PCIe 1 slot so Im kind of limited as to what can be used. I'm in Canada btw so if there's a Canadian source that would be extra helpful.


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27 May 2023 14:39 #272268 by tommylight
You can use a parallel port without a BOB, i used it a lot, still working after over 10 years in use, but that does require a lot of care and knowledge about wiring and signaling and grounding.
BOB's used to be a cheap way of protecting the parallel port (and consequently the PC) from any mishaps on the machine side. Now used PC's are cheap so the main reason for using those is to have a bit of protection for the PC and easier wiring.
When choosing a BOB, the main thing is do you need galvanic isolation from machine to PC, usually not very important, but isolated cheap BOB's use very slow optocouplers so that limits step pulse rate a lot.
The non isolated ones use buffers and those are usually OK, if there is no need for galvanic isolation.
Mesa is a different beast altogether, but the simple explanation is much, much faster everything, (parallel port can usually do 10000 to 50000 steps per second, Mesa can do up to 10 million steps per second), every Mesa board has the equivalent of two or three parallel ports as inputs and outputs, can be expanded a lot, and so on.
Since you are new, if you can stretch finances, do get a Mesa 7i96S, those are available and have everything needed for a most machines, and can be later expanded, a lot.
As for parallel port, get a cheap PC, a cheap BOB, wire it and start using the machine, you can change at any time later, but the experience you get from it, stays with you, always.

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01 Jun 2023 22:03 #272658 by Halbear
Thanks for the excellent response, that's a lot of helpful info right there, I appreciate it!

Happy to know too that there's no real need to match a BOB to a parallel port, it would have made shopping a little tough. Things like Mesa boards have to be imported here which can really delay things depending entirely on the mood of the border people.
The following user(s) said Thank You: tommylight

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