I don’t see the attachment. Sent from my iPhone
> On Feb 15, 2025, at 13:22, Mike Stein via cctalk <cctalk@classiccmp.org> > wrote: > > In the keyboard section of the attached document there are instructions for > testing with a terminal & USB>TTL RS-232 adapter. > >> On Sat, Feb 15, 2025 at 12:43 AM Steve Lewis <lewiss...@gmail.com> wrote: >> >> Thanks, I had forgotten about the Kaypro. Looks like it uses a "custom" >> 4-pin wire (one of them being 5V power). So just level-shift the TX/RX >> pins through a MAX232 IC and it would talk to another R-232 system at 300 >> baud eh? Might have to seek out a lone Kaypro keyboard to give it a try. >> >> I suspect some of the "serial style" mid-1980s IBM Model M keyboards are >> similar. But I'm still wondering if anyone used this concept in the late >> 1960s - teletypes were expensive, flipping switches was tedious, so >> keyboard alternates were hot items by early 70's (hence the TVT popularity). >> >>> On Fri, Feb 14, 2025 at 5:28 PM Mike Stein <mhs.st...@gmail.com> wrote: >>> >>> 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 < >>> cctalk@classiccmp.org> 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 < >>>> cctalk@classiccmp.org> 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:henry.r.b...@gmail.com] >>>>> Sent: Thursday, February 13, 2025 3:54 PM >>>>> To: General Discussion: On-Topic and Off-Topic Posts < >>>>> cctalk@classiccmp.org> >>>>> Cc: Rick Bensene <ri...@bensene.com> >>>>> Subject: Re: [cctalk] Re: RS232 - parallel modems!? >>>>> >>>> >>>
