[cctalk] Re: RS232 then and now (bitbanging)

Well... From what I've seen (in these 1980 microprocessor cases), they are using "bit shifters" to help pull off their bit banging. So it's not a true self sufficient kind of bit banging. I'm defining a UART as something that also does the work of applying the start/parity and stop bit. The earl

[cctalk] Re: RS232 then and now

On 02/02/2025 15:48, Nigel Johnson Ham via cctalk wrote: On 2025-02-01 08:43, Frank Leonhardt via cctalk wrote: On 31/01/2025 23:07, Chuck Guzis via cctalk wrote: On 1/31/25 13:57, Tony Duell via cctalk wrote: On Fri, Jan 31, 2025 at 9:38 PM Fred Cisin via cctalk wrote: The first paralle

[cctalk] Re: RS232 then and now

On Sun, 2 Feb 2025, Steve Lewis via cctalk wrote: Didn't the original TRS-80 have a kind of screw up, where the tape and display connector were the same? Actually, years later the Atari Lynx had a similar mishap - the power charger and headphone jack port look identical? (something like that, an

[cctalk] Re: Bit-banging nightmares, wa: Re: Re: RS232 then and now (bitbanging)

On 2/2/25 17:07, Christian Kennedy via cctalk wrote: > I am reminded of the Regitel system, a POS system from the early > 1970's.  We ran 64 model 33's off of a three-or-four board Regitel mux > on a Nova 800; you'd basically load a bunch of registers with the > current bit for each port and it wou

[cctalk] Re: RS232 then and now (bitbanging)

On 2/2/25 17:22, Will Cooke via cctalk wrote: > > > Not quite lost. The 1802 crowd is doing amazing things. > See https://groups.io/g/cosmacelf/message/33678 > > And if you know anything about the 1802, it's, uh, not so speedy. At its introduction,it was one of few static CMOS CPUs. You could

[cctalk] Re: Microsoft 50 years

I might be banished for saying - but, I actually like Microsoft. It's had up's and downs for sure. Multitasking MS-DOS 4.0, mmhmmm I like CRLF line endings :) It's more "OG"! It is two separate actions - if you want to LineFeed and THEN CarriageReturn. Just because we now have a super

[cctalk] Re: RS232 then and now

Didn't the original TRS-80 have a kind of screw up, where the tape and display connector were the same? Actually, years later the Atari Lynx had a similar mishap - the power charger and headphone jack port look identical? (something like that, and would cause damage if used incorrectly) Steve

[cctalk] Re: Apple & History (Was: Microsoft 50 years)

My stable of old Macs running BOINC network computing projects keeps the upstairs of my shop heated in the Winter. Fans running to cut out wildfire air pollution are often noisier than the computers. I've been using VueScan for 19 years. A great program. You can even do RAW scans with it an

[cctalk] Re: RS232 then and now (bitbanging)

> On 02/02/2025 2:47 PM EST Steve Lewis via cctalk > wrote: > ... > > Another example is the Color Computer 3. UltimateTerm 2.4 from 1987 could > bit-bang reliably 9600 baud (also Twilight Term from 1996). The CoCo3 had > a higher speed CPU option than its original. "bit banging" (imo) is

[cctalk] Bit-banging nightmares, wa: Re: Re: RS232 then and now (bitbanging)

I am reminded of the Regitel system, a POS system from the early 1970's.  We ran 64 model 33's off of a three-or-four board Regitel mux on a Nova 800; you'd basically load a bunch of registers with the current bit for each port and it would bang them out; input was the reverse.  It was on the p

[cctalk] Re: RS232 then and now

>Message: 31 >Date: Sun, 2 Feb 2025 07:29:15 + >From: Tony Duell >Subject: [cctalk] Re: RS232 then and now > >On Sat, Feb 1, 2025 at 10:54 PM Fred Cisin via cctalk > wrote: > > >> >> IBM used a DB25 socket for their printer port at the computer end, >> (male on the card for serial, female on t

[cctalk] Re: RS232 then and now

>Message: 26 >Date: Sat, 1 Feb 2025 18:13:17 -0500 >From: Nigel Johnson Ham >Subject: [cctalk] Re: RS232 then and now > >On 2025-02-01 18:11, Chuck Guzis via cctalk wrote: >> One mystery to me was why did the industry stick with the EIA-232 levels >> for terminals and whatnot long after differenti

[cctalk] Re: RS232 then and now

On 2/2/25 11:34, Chuck Guzis via cctalk wrote: My first personal printer was a Diablo Hitype I with the OEM 12-bit interface. I used two S100 parallel ports (don't recall the card) and wrote my own logic-seeking bidirectional driver. Still have the code somewhere. While that produced very nic

[cctalk] Re: RS232 then and now

On Sun, 2 Feb 2025, Chuck Guzis via cctalk wrote: > > I forgot to mention: MIDI has been another notable example where you want > > to wire a UART to another kind of line driver. I also have a computer > > where one of USARTs is multiplexed (software-configurable) between an > > RS-232 line d

[cctalk] Re: RS232 then and now

On 2/2/25 10:42, Maciej W. Rozycki via cctalk wrote: > On Sun, 2 Feb 2025, Maciej W. Rozycki wrote: > I forgot to mention: MIDI has been another notable example where you want > to wire a UART to another kind of line driver. I also have a computer > where one of USARTs is multiplexed (software

[cctalk] Re: RS232 then and now (bitbanging)

> And it reminded me of some of my own past exploration into systems that did > RS232 without an UART. > > One example is the NEC PC-8001 (system from about 1979). I recall having > trouble getting it past 600 baud for some reason. Infamously also the Commodore 64, which a) had the wrong presc

[cctalk] Re: RS232 then and now

after all, it's not the Epson interface ;-) On Sun, Feb 2, 2025 at 10:48 AM Nigel Johnson Ham via cctalk < cctalk@classiccmp.org> wrote: > On 2025-02-01 08:43, Frank Leonhardt via cctalk wrote: > > > > On 31/01/2025 23:07, Chuck Guzis via cctalk wrote: > >> On 1/31/25 13:57, Tony Duell via cctalk

[cctalk] Re: RS232 then and now

These days you can get rs232<>TTL converter modules for less than the price of a MAX... chip; 3.3-5V (no 12V), only slightly larger than a MAX chip only; for an extra buck or so you can get it with a DE-9 connector https://www.amazon.ca/Converter-Breakout-Computer-Electronic-Components/dp/B0B19ZCD

[cctalk] Re: RS232 then and now (bitbanging)

On Sunday, February 2, 2025 at 11:47:24 AM PST, Steve Lewis via cctalk wrote: > [...] "bit banging" (imo) is the > host system doing the work of producing the start/stop bits on its own. > Which seems to be a "lost art" and why I've wondered if anyone has tried > bit-banging on a modern-day 3

[cctalk] Re: RS232 then and now (bitbanging)

> On Feb 2, 2025, at 3:23 PM, Jonathan Stone via cctalk > wrote: > > > On Sunday, February 2, 2025 at 11:47:24 AM PST, Steve Lewis via cctalk > wrote: > > >> [...] "bit banging" (imo) is the >> host system doing the work of producing the start/stop bits on its own. >> Which seems to be a

[cctalk] Re: RS232 then and now (bitbanging)

I came across the following more recent discussion: 2022-05-05 Bit banging on a Tandy CoCo1 - Wikistix And it reminded me of some of my own past exploration into systems that did RS232 without an UART. One example is the NEC PC

[cctalk] Re: RS232 then and now

On 02/02/2025 18:32, Paul Koning via cctalk wrote: On Feb 1, 2025, at 5:57 PM, Chuck Guzis via cctalk wrote: On 2/1/25 13:31, Frank Leonhardt via cctalk wrote: I started with minilogs which were +/- 10V logic. Anyone remember those? I remember HTL (15V) being basically a high-voltage versio

[cctalk] Re: RS232 then and now

On Sun, 2 Feb 2025, Maciej W. Rozycki wrote: > > What I meant is that a lot of modern computer modules come with serial > > ports that are not RS232 but rather using standard logic levels (TTL 0 > > and 5 volts, or perhaps lower voltages such as 0 and 3.3 volts) for > > their signaling. Those

[cctalk] Re: RS232 then and now

> On Feb 1, 2025, at 5:57 PM, Chuck Guzis via cctalk > wrote: > > On 2/1/25 13:31, Frank Leonhardt via cctalk wrote: > >> I started with minilogs which were +/- 10V logic. >> >> Anyone remember those? > > I remember HTL (15V) being basically a high-voltage version of DTL. > > --Chuck Sim

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, Paul Koning wrote: > I don't know if the MAX3222 is older, or just different. The RS232 > standard doesn't apply to those high rates. And I vaguely remember > seeing words that imply the line drivers should have controlled > rise/fall times. So I think the MAX3222 limits

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, Paul Koning wrote: > >> Was that with an actual RS232 port, i.e., a device using RS232 signal > >> levels, or a "TTL" logic level serial port? I'm guessing the latter. > > > > I'm not sure what you mean by 'a "TTL" logic level serial port', please > > elaborate. Do you mea

[cctalk] Re: RS232 then and now

On 2/2/25 08:43, Nigel Johnson Ham via cctalk wrote: > My first printer was a TeleType ASR35 (with typing reperforator!)    I > got a few shocks being careless with the 20mA loop at 130VDC! > > The ease of paper tape meant I was very late getting into the cassette > for backup, although I did bui

[cctalk] Re: RS232 then and now

On 2025-02-02 11:18, Mike Stein via cctalk wrote: Same here! Had a 101 in the basement connected to my PET upstairs because of space and noise, with a 35-40 foot long ribbon cable far exceeding the recommended maximum cable length; never a problem. m On Sat, Feb 1, 2025 at 6:03 PM Fred Cisin v

[cctalk] Re: A baudy tale

Anybody remember Bunker Ramo? Still have one of their two-shoebox-sized modems somewhere... On Sat, Feb 1, 2025 at 8:28 PM Rick Bensene via cctalk < cctalk@classiccmp.org> wrote: > > > Vadic had a variant 1200 baud system that wasn't compatible with 212, > too, as I recall. > > Yup, they did. C

[cctalk] Re: RS232 then and now

Same here! Had a 101 in the basement connected to my PET upstairs because of space and noise, with a 35-40 foot long ribbon cable far exceeding the recommended maximum cable length; never a problem. m On Sat, Feb 1, 2025 at 6:03 PM Fred Cisin via cctalk wrote: > >>> Another pet gripe of mine i

[cctalk] Re: RS232 then and now

On 02/02/2025 15:48, Nigel Johnson Ham via cctalk wrote: On 2025-02-01 08:43, Frank Leonhardt via cctalk wrote: On 31/01/2025 23:07, Chuck Guzis via cctalk wrote: On 1/31/25 13:57, Tony Duell via cctalk wrote: On Fri, Jan 31, 2025 at 9:38 PM Fred Cisin via cctalk wrote: The first paralle

[cctalk] Re: RS232 then and now

On 2025-02-01 08:43, Frank Leonhardt via cctalk wrote: On 31/01/2025 23:07, Chuck Guzis via cctalk wrote: On 1/31/25 13:57, Tony Duell via cctalk wrote: On Fri, Jan 31, 2025 at 9:38 PM Fred Cisin via cctalk wrote: The first parallel printers might have been Centronics.  Hence the interface

[cctalk] Re: A baudy tale

On 01/02/2025 00:05, Donald Whittemore via cctalk wrote: Also using NCR/Tally units. We used Racal-Milgo modems. These things were about the size of a large home stereo receiver. We started at 2400 baud. The units could do 3600 or 4800 (I don’t remember which) if a circuit board strap was moved.

[cctalk] Re: A baudy tale

On 02/02/2025 01:20, Donald Whittemore via cctalk wrote: It was POTS. So I wonder how it worked in the early 1970s. Multiple lines? Interesting modulation? QAM before it was mainstream? FSK half duplex?

[cctalk] Re: RS232 then and now

On 01/02/2025 17:33, Chuck Guzis via cctalk wrote: Another pet gripe of mine is calling the old 50-way SCSI/etc. connector a "Centronics" connector,regardless of application or number of connections. I prefer to refer to them as "blue ribbon" connectors, developed by Amphenol in 1950 and used ex

[cctalk] Re: Microsoft 50 years

On 31/01/2025 18:19, Christian Liendo via cctalk wrote: I was debating sending this, but Microsoft is part of computing history and fifty years is a milestone. https://news.microsoft.com/microsoft-50/ My early Microsoft story. I noticed a problem in Microsoft 6502 BASIC 1.0 rev 3.2 (I saw the

[cctalk] Re: RS232 then and now

On 31/01/2025 23:07, Chuck Guzis via cctalk wrote: On 1/31/25 13:57, Tony Duell via cctalk wrote: On Fri, Jan 31, 2025 at 9:38 PM Fred Cisin via cctalk wrote: The first parallel printers might have been Centronics. Hence the interface and blue ribbon connector being called "Centronics para

[cctalk] Re: A baudy tale

On 01/02/2025 21:35, David Wise wrote: My experience (Tektronix mainframe via Vadic 2400) was POTS, early 1980's. By the early 1980s V.22 and V.22bis were common (I had a desk full). This bing in the early 1970s, is what's intriguing me. People with large budgets had better toys and I want

[cctalk] Re: RS232 then and now

On Sat, Feb 01, 2025 at 11:01:34PM +, Chuck Guzis via cctalk wrote: > On 2/1/25 13:12, David Wise via cctalk wrote: [...] >> I used the 1488 and 1489 RS232 chips as level shifters on the >> semiconductor RAM board I designed for the IBM 1620. Handy. > In the 1970s/80s, there seemed to be two ca

[cctalk] Re: RS232 then and now

On 02/02/2025 07:29, Tony Duell via cctalk wrote: On Sat, Feb 1, 2025 at 10:54 PM Fred Cisin via cctalk wrote: IBM used a DB25 socket for their printer port at the computer end, (male on the card for serial, female on the card for parallel "Centronics") THAT, of course caused some idiots t