[cctalk] Re: RS232 - parallel modems!?

Rick Bensene: find That'd be neat to see, if you do find the Xircom parallel modem. I've seen combo ones and their "parallel-ethernet" devices (which seem to go for quite a premium these days), but not the modem only. Suppose they weren't too popular, as even laptops started to have built in modems. These days, I do use an SDLPT, that lets you use SD-cards to transfer data into a system over the parallel port. I suppose that's the same general principle (of read/writing one full byte at a time to a device). I haven't measured its performance yet (but would characterize it as being comparable to a physical 3.5" floppy disk drive kind of performance - I think copying Quake took over 40 minutes, something like that; but I'd like to get more accurate about it, down to an actual bytes-per-second rate). Measuring that might give me an answer on how fast something like Laplink/Interlink cable should be able to perform. As another experiment, I'll drop that ~7MHz 16550 serial card into a 386, and see if I can get a 386 to push data out on RS-232 faster than 115200. It should, but we'll see! And I think I will do an RS-232 themed talk in June VCF, if a spot is still open - I think I have enough now to make it interesting. One area I'm a little stuck on is verifying that anyone actually did make an RS-232 keyboard. Even for TV Typewriter, I'm not sure if I'd characterize that as RS-232 related. And Gordon Bell integrated an ASR-33 (current loop) to the PDP-1, but might not be accurate to call that RS-232 (but can't a current loop based thing be adapted to voltage?). I thought the POLY-88 keyboard was RS-232, but it'll be awhile before I can get back to that equipment. -Steve On Thu, Feb 13, 2025 at 6:32 PM Rick Bensene via cctalk < cctalk(a)classiccmp.org&gt; wrote: information Xircom that expensive. > For a laptop that didn’t have a PCMCIA port, and you wanted it on an > Ethernet network, this was an acceptable way to go. Performance wasn’t > great, but most of the time laptops like this were used for TELNET > connections to other hosts on the local network for “GREEN SCREEN” type > applications that ran entirely on the remote host. Performance in such > cases wasn’t nearly as much of a concern as it would be in the not too > distant future. > find > > -Rick > > > > From: Henry Bent [mailto:henry.r.bent@gmail.com] > Sent: Thursday, February 13, 2025 3:54 PM > To: General Discussion: On-Topic and Off-Topic Posts < > cctalk(a)classiccmp.org&gt; > Cc: Rick Bensene &lt;rickb(a)bensene.com&gt; > Subject: Re: [cctalk] Re: RS232 - parallel modems!? >