I believe that at least Kaypro used a TTL form of RS-232 for the keyboard; in fact, ISTR using an RS M100 notebook (+/- 5V) in place of a keyboard in distant days.
On Fri, Feb 14, 2025 at 12:27 PM Steve Lewis via cctalk < [email protected]> wrote: > Rick Bensene: > > > I will try to find my Xircom parallel port Modem and Ethernet adapters in > > a box somewhere in my storage area and take a photo of them. If I can > find > > them, I’ll post a link here to the photos so those in disbelief can see > > them. > > > 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 < > [email protected]> wrote: > > > Henry wrote: > > > > > I remember those, and when I went searching to look for more > information > > on them I found something I > hadn't stumbled on before - apparently > Xircom > > made a parallel port Ethernet adapter. It must have > > > been pretty painful. The parallel port wasn't a great high speed > > interface… > > > > ---- > > > > Yes, I have one of those parallel port Ethernet devices too. But, > > remember, back at that time, Ethernet was commonly 10Mb/Sec. I think > that > > 100Mb/Sec was only located in high-end datacenters and was very > 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. > > > > I will try to find my Xircom parallel port Modem and Ethernet adapters in > > a box somewhere in my storage area and take a photo of them. If I can > find > > them, I’ll post a link here to the photos so those in disbelief can see > > them. > > > > -Rick > > > > > > > > From: Henry Bent [mailto:[email protected]] > > Sent: Thursday, February 13, 2025 3:54 PM > > To: General Discussion: On-Topic and Off-Topic Posts < > > [email protected]> > > Cc: Rick Bensene <[email protected]> > > Subject: Re: [cctalk] Re: RS232 - parallel modems!? > > >
