[cctalk] Re: RS232 then and now

And several RS computers and peripherals used 4-pin DIN connectors for RS-232 serial... On Mon, Feb 3, 2025 at 1:56 AM Fred Cisin via cctalk wrote: > 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

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

On 2025-02-15 09:46, Paul Koning via cctalk wrote: On Feb 15, 2025, at 4:10 AM, Bill Duncan via cctalk wrote: On Mon, Feb 03, 2025 at 06:09:28AM +, Chuck Guzis via cctalk wrote: On 2/2/25 17:22, Will Cooke via cctalk wrote: Not quite lost. The 1802 crowd is doing amazing things. See

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

> On Feb 15, 2025, at 4:10 AM, Bill Duncan via cctalk > wrote: > > On Mon, Feb 03, 2025 at 06:09:28AM +, Chuck Guzis via cctalk wrote: >> 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/cosmac

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

On Mon, Feb 03, 2025 at 06:09:28AM +, Chuck Guzis via cctalk wrote: > 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,

[cctalk] Re: RS232 then and now

On Mon, Feb 3, 2025, 7:06 PM Cameron Kaiser via cctalk < cctalk@classiccmp.org> wrote: > > >> DEC did something similar with the Pro, except they used a DA-15 > connector > >> to carry video (monochrome as well as RGB), keyboard data (4800 bps > UART) > >> and 12 volt power. > >> > > DEC Rainbow t

[cctalk] Re: RS232 then and now

>> DEC did something similar with the Pro, except they used a DA-15 connector >> to carry video (monochrome as well as RGB), keyboard data (4800 bps UART) >> and 12 volt power. >> > DEC Rainbow too... And it's easy to short power to another line and take > out the line drivers in the keyboard...

[cctalk] Re: RS232 then and now

On Sun, Feb 2, 2025 at 11:38 AM Mike Stein via cctalk wrote: > 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. I ran my 101 off the User Port on my Commo

[cctalk] Re: RS232 then and now

On Sat, Feb 1, 2025 at 6:03 PM Fred Cisin via cctalk wrote: > I loved the 101. > When I retired mine, I tried unsuccessfully to get $25 each at swaps. I had a Centronics 101 back in college. I'm sure I got it because nobody wanted it. Probably got it for $25 or less at a Hamfest or just "get th

[cctalk] Re: RS232 then and now

On Mon, Feb 3, 2025 at 11:09 AM Paul Koning via cctalk < cctalk@classiccmp.org> wrote: > > > > On Feb 2, 2025, at 7:42 PM, Robert Feldman via cctalk < > cctalk@classiccmp.org> wrote: > > > > > > My vote for the worst connector screw-up is the AT&T (Olivetti) 6300. > Its monochrome monitor used a D

[cctalk] Re: RS232 then and now

ct: [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-Breakou

[cctalk] Re: RS232 then and now

> On Feb 2, 2025, at 7:42 PM, Robert Feldman via cctalk > wrote: > > > My vote for the worst connector screw-up is the AT&T (Olivetti) 6300. Its > monochrome monitor used a DB25 to supply both the signals and 12 volts to > power the monitor. > > Bob DEC did something similar with the Pro

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

On Mon, Feb 3, 2025 at 10:58 AM ben via cctalk wrote: > > On 2025-02-02 11:09 p.m., Chuck Guzis via cctalk wrote: > > 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 > >> > >>

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

On 2025-02-02 11:09 p.m., Chuck Guzis via cctalk wrote: 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 introductio

[cctalk] Re: RS232 then and now

Ah, I wrote all about the IBM PC 5150 tape deck capability here: 5150: Setting up Tape Deck Connection (because the 5150 can) — voidstar Indeed it is exactly the same as the Tandy cable. I always assumed since Micr

[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: 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: RS232 then and now

Steve On Sun, Feb 2, 2025 at 6:53 PM Robert Feldman via cctalk < cctalk@classiccmp.org> wrote: > >Message: 31 > >Date: Sun, 2 Feb 2025 07:29:15 + > >From: Tony Duell > >Subject: [cctalk] Re: RS232 then and now > > > >On Sat, Feb 1, 2

[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] 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, >

[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 te

[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: 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: 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: 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: 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

[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 the card for parallel "Centronics") > THAT, of course caused some idiots to attempt to use the parallel port for > serial

[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 differential EIA-422 was introduced. Higher-speed, better noise immunity, single-ended power supply... Seems that the popular places w

[cctalk] Re: RS232 then and now

One mystery to me was why did the industry stick with the EIA-232 levels for terminals and whatnot long after differential EIA-422 was introduced. Higher-speed, better noise immunity, single-ended power supply... Seems that the popular places were Appletalk and ST506 data lines. But not on DTE/D

[cctalk] Re: RS232 then and now

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 extensively in commercial telephone systems long before

[cctalk] Re: RS232 then and now

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 camps of though WRT EIA receivers/drivers. There was the Motorola 1488/1489 crowd

[cctalk] Re: RS232 then and now

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

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, Frank Leonhardt via cctalk wrote: I think the Epson MX80 was responsible for standardising the Centronics interface :-) Not only was it TTL only and therefore easier to implement in hardware, but it was much faster than RS-232. You could get other interfaces as add-on boards,

[cctalk] Re: RS232 then and now

On 01/02/2025 19:10, Paul Koning via cctalk wrote: On Feb 1, 2025, at 8:37 AM, Frank Leonhardt via cctalk wrote: I certainly agree TTL would have made sense for microprocessors but earlier computers ran at much higher voltages, and lots of them :-) So did early logic ICs. TTL happens to be v

[cctalk] Re: RS232 then and now

I used the 1488 and 1489 RS232 chips as level shifters on the semiconductor RAM board I designed for the IBM 1620. Handy. Dave Wise

[cctalk] Re: RS232 then and now

On 2/1/25 13:10, Paul Koning via cctalk wrote: you might also find high end systems with ECL in them (-3 volts??? I forgot). If you ran Motorola ECL the Motorola way, with Vcc at gnd and Vee at -5.2 for MECL 10K and -4.5 for 100K) logic levels were -0.8 V for a 1 and -1.6 V for a zero. If

[cctalk] Re: RS232 then and now

On 2/1/25 13:10, Paul Koning via cctalk wrote: you might also find high end systems with ECL in them (-3 volts??? I forgot). If you ran Motorola ECL the Motorola way, with Vcc at gnd and Vee at -5.2 for MECL 10K and -4.5 for 100K) logic levels were -0.8 V for a 1 and -1.6 V for a zero. I

[cctalk] Re: RS232 then and now

On 01/02/2025 18:42, Frank Leonhardt via cctalk wrote: I think the Epson MX80 was responsible for standardising the Centronics interface :-) Ooh yes, fond memories, that was the first printer I could actually afford. Julf

[cctalk] Re: RS232 then and now

AMP and Amphenol were different companies, officially. -- Will On Sat, Feb 1, 2025 at 2:40 PM Nigel Johnson Ham via cctalk wrote: > > On 2025-02-01 13:25, Frank Leonhardt via cctalk wrote: > > On 01/02/2025 17:33, Chuck Guzis via cctalk wrote: > >> Another pet gripe of mine is calling the old 50

[cctalk] Re: RS232 then and now

On 2025-02-01 13:25, Frank Leonhardt via cctalk wrote: 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 ribbo

[cctalk] Re: RS232 then and now

> On Feb 1, 2025, at 8:37 AM, Frank Leonhardt via cctalk > wrote: > > On 01/02/2025 02:31, roger arrick via cctalk wrote: >> In 1977, at age 16, I went to work for Noakes Data Communications in Irving >> Texas. >> >> We built an 8080 industrial computer, made modems, and repaired lots of co

[cctalk] Re: RS232 then and now

> On Jan 31, 2025, at 10:37 PM, Maciej W. Rozycki wrote: > >> ... > > The serial port hardware I refer to uses a UART wired to a Zywyn ZT3243F > line driver, which according to the manufacturer's datasheet signals at > ±5V minimum transmitter voltage levels and accepts up to ±25V receiver

[cctalk] Re: RS232 then and now

> On Jan 31, 2025, at 10:37 PM, Maciej W. Rozycki wrote: > > On Fri, 31 Jan 2025, Paul Koning wrote: > >>> FWIW I was able to get reliable serial communication under Linux of up to >>> 3.5Mbps with off-the-shelf proper PCIe UART hardware clocked at 62.5MHz >>> despite that line drivers used

[cctalk] Re: RS232 then and now

On 2/1/25 09:42, Frank Leonhardt via cctalk wrote: > You could get other interfaces as add-on boards, including RS-232, > Apple, TRS-80 and IEE488. I believe they got a 50% of market share for > printers with this, from a standing start. I vaguely recall that the MX-80 came with the parallel inte

[cctalk] Re: RS232 then and now

On 31/01/2025 08:20, Steve Lewis via cctalk wrote: Then, was it the SAGE program that demonstrated the idea of doing this kind of data exchange across copper phone lines? That is, the idea of computers collaborating not just in a room, but across long distances (miles)? And doing so by using

[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: RS232 then and now

> On Jan 31, 2025, at 6:19 PM, Cameron Kaiser via cctalk > wrote: > > >> Low speed modems are just analog devices that can pass any signal up to >> whatever the design speed limit is. For example, a 103 modem is good up >> to 300 bps, but will happily carry anything less. A 202 modem (see

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, ben via cctalk wrote: > > > I'm happy to see people using the correct shell letter for DSubs around > > > here! Oldschool wisdom. > > > > You kinda have to when you get at things such as DA-3W3. > > I have no idea what that is, but I am sure that has no SUB-MINIATURE price

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, Steve Lewis wrote: > Reading the async-expansion for the IBM 5110, it talks about -25 to +25V > (the original spec of RS232?). On the 1980 Color Computer 1, I noticed it > uses -12V to +12V for its RS232. Later in the 1990s, laptops wanted to > sip less less power, and I thi

[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 paral

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, Warner Losh 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 me

[cctalk] Re: RS232 then and now

On 2025-02-01 10:11 a.m., Maciej W. Rozycki via cctalk wrote: On Sat, 1 Feb 2025, roger arrick via cctalk wrote: I'm happy to see people using the correct shell letter for DSubs around here! Oldschool wisdom. You kinda have to when you get at things such as DA-3W3. Maciej I have no i

[cctalk] Re: RS232 then and now

On 2/1/25 09:05, roger arrick via cctalk wrote: > I'm happy to see people using the correct shell letter for DSubs around here! > Oldschool wisdom. > I get irritated hearing people on the vintage computing groups calling > everything DB. > Here's a quick write up about it - there is no DB9! 🙂

[cctalk] Re: RS232 then and now

On Sat, 1 Feb 2025, roger arrick via cctalk wrote: > I'm happy to see people using the correct shell letter for DSubs around > here! Oldschool wisdom. You kinda have to when you get at things such as DA-3W3. Maciej

[cctalk] Re: RS232 then and now

Off-Topic Posts Cc: Dennis Boone Subject: [cctalk] Re: RS232 then and now > One used to (in the 1970s) be able to purchase off-the-shelf "long > haul" modems that converted between EIA signal levels and > current-loop. Sometimes called "line drivers", because that&

[cctalk] Re: RS232 then and now

> One used to (in the 1970s) be able to purchase off-the-shelf "long > haul" modems that converted between EIA signal levels and > current-loop. Sometimes called "line drivers", because that's not confusingly overloaded terminology or anything. I was about to say "e.g. Gandalf LDS family", bu

[cctalk] Re: RS232 then and now

On 2/1/25 02:31, Frank Leonhardt via cctalk wrote: > On 31/01/2025 18:55, Steve Lewis via cctalk wrote: > As I've mentioned elsewhere, "UART" is Intel's term for an ACIA; and > other names exist from other manufacturers. Just a buffered shift > register and other logic in the same chip. The venee

[cctalk] Re: RS232 then and now

On 2025-02-01 6:37 a.m., Frank Leonhardt via cctalk wrote: IME +/- 12V was a de-facto standard on microcomputers because they already had a +12V and -12V rail, along with +5V. The ubiquitous 4116 DRAM needed +5V, -5V and +12V so +/- 5V was a popular option too. Apple was smart with their swit

[cctalk] Re: RS232 then and now

On 01/02/2025 02:31, roger arrick via cctalk wrote: In 1977, at age 16, I went to work for Noakes Data Communications in Irving Texas. We built an 8080 industrial computer, made modems, and repaired lots of comm gear. RS232 was what we lived and breathed. And back then almost all the contro

[cctalk] Re: RS232 then and now

On 31/01/2025 18:55, Steve Lewis via cctalk wrote: re: on UARTS.. Didn't it basically standardize the process of that task of converting a byte to bits and vice versa, in a fashion specified by RS232? And do so at the above-300-baud rates, since that task was too stressful for 1MHz processors to

[cctalk] Re: RS232 then and now

I wouldn't call them 'adjusted' to TTL levels. They're simply the levels that are used between UART and line buffers, which, yes, are TTL but not something arranged particularly for these devices. Of course, they aren't any more suitable for external connections than any other internal board-level

[cctalk] Re: RS232 then and now

I wasn't aware of current loop, been reading about it today. I also came across an article on how RS232 is reasonable for non-noisy environments, but for a busy industrial floor interference can become an issue. Read through some old GoogleGroup archive, discussions in 1997 of the buggy 8250 supp

[cctalk] Re: RS232 then and now

> > I'm not sure what you mean by 'a "TTL" logic level serial port', please > elaborate. Do you mean signalling used between the UART and line drivers > by any chance, such as with a serial connection made between UARTs without That confused me at first as well. As you concluded: yes, not a

[cctalk] Re: RS232 then and now

On Fri, Jan 31, 2025, 8:37 PM Maciej W. Rozycki via cctalk < cctalk@classiccmp.org> wrote: > On Fri, 31 Jan 2025, Paul Koning wrote: > > > > FWIW I was able to get reliable serial communication under Linux of up > to > > > 3.5Mbps with off-the-shelf proper PCIe UART hardware clocked at > 62.5MHz >

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, Paul Koning wrote: > > FWIW I was able to get reliable serial communication under Linux of up to > > 3.5Mbps with off-the-shelf proper PCIe UART hardware clocked at 62.5MHz > > despite that line drivers used with said hardware (soldered onboard) were > > spec'd for up to 1M

[cctalk] Re: RS232 then and now

5 8:15 PM To: General Discussion: On-Topic and Off-Topic Posts Cc: Steve Lewis ; Doug Jackson Subject: [cctalk] Re: RS232 then and now I own my entire working career to some random happenings as a kid with interfacing equipment to IBM PC clones using RS232. As a late teenager I used to hang out

[cctalk] Re: RS232 then and now

I own my entire working career to some random happenings as a kid with interfacing equipment to IBM PC clones using RS232. As a late teenager I used to hang out at the local computer store who sold Toshiba gear. I had a knack for making cables that allowed them to connect brother printers using R

[cctalk] Re: RS232 then and now

> Low speed modems are just analog devices that can pass any signal up to > whatever the design speed limit is. For example, a 103 modem is good up > to 300 bps, but will happily carry anything less. A 202 modem (see > below) is designed for 1200 but also will work at lower speeds, and has

[cctalk] Re: RS232 then and now

On 1/31/25 12:57, Dennis Boone via cctalk wrote: > Some dates relevant to this discussion: > > "First" monolithic IC in the lab: 1960. > > First PCM multiplexed telephone circuit (T1, 1.544 Mbit/s): 1962. > > First UART IC: 1972. In the mid 70s, I was project manager for an internal product of

[cctalk] Re: RS232 then and now

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 parallel" > > The first printer that Radio Shack

[cctalk] Re: RS232 then and now

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 parallel" The first printer that Radio Shack/Tandy sold for the TRS-80 (at least in the UK) -- the 'TRS

[cctalk] Re: RS232 then and now

On 2025-01-31 14:44, Steve Lewis via cctalk wrote: But for other fodder, I'm reading over the async card for the IBM 5110. Page 12 of this IBM 5110 doc has a block diagram of IBMs version of "asynchronous card" - SY31-0552-3_IBM_5110_System_Logic_Manual_197902.pdf

[cctalk] Re: RS232 then and now

On Fri, Jan 31, 2025 at 9:36 PM Fred Cisin via cctalk wrote: > > On Fri, 31 Jan 2025, Chuck Guzis via cctalk wrote: > > As far as RS232 and history, I submit that current-loop has more of a > > place in telegraphy, as it's far more suited to long distances and is > > less susceptible to signal noi

[cctalk] Re: RS232 then and now

> On Jan 31, 2025, at 4:30 PM, Maciej W. Rozycki via cctalk > wrote: > > On Fri, 31 Jan 2025, Steve Lewis via cctalk wrote: > >> So while some protocol gets developed for that system, I experimented with >> other actual vintage system trying to "talk to" a modern PC (where "modern >> PC" is

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, David Wade via cctalk wrote: Lets look at some of the other pins:- RTS/CTS   - Request to send/clear to send - Hardware flow control. DTR/DSR - Is comms up and running RI  - Ring Indicator - a call has arrived TCK/RCK - Used for timing on synchronous links so BI-

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, Steve Lewis via cctalk wrote: > So while some protocol gets developed for that system, I experimented with > other actual vintage system trying to "talk to" a modern PC (where "modern > PC" is a 3GHz i7 laptop). For the actual task of transferring files, there > are many othe

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, Chuck Guzis via cctalk wrote: As far as RS232 and history, I submit that current-loop has more of a place in telegraphy, as it's far more suited to long distances and is less susceptible to signal noise. Many early 1970s serial interfaces offered the choice between 20ma or

[cctalk] Re: RS232 then and now

On 2025-01-31 15:18, Wayne S via cctalk wrote: Steve, remember that digital electronics ( I.E. integrated circuits like uarts) weren’t around during the early days of data transmission. It was all analog back then, coils, capacitors, and resistors, so then ideas regarding fast transmission

[cctalk] Re: RS232 then and now

> Steve, remember that digital electronics ( I.E. integrated circuits > like uarts) weren’t around during the early days of data > transmission. It was all analog back then, coils, capacitors, and > resistors, so then ideas regarding fast transmission had to wait for > the technology to evolve

[cctalk] Re: RS232 then and now

> So I tested a bunch of (relatively modern, post-UART) vintage > systems: 4.77MHz PC w/ 1.8MHz/8250, 12MHz 286 (with Unknown), > 386/486, and a Pentium all null-modem connected to a modern-make PC - > just to verify how fast they should be pushed (download) a data > stream. None of them (not

[cctalk] Re: RS232 then and now

On Fri, 31 Jan 2025, Frank Leonhardt via cctalk wrote: And for amusement, someone wrote in the PCW saying they'd heard a salesperson at Radio Shack trying to convince a punter that RS is RS232 stood for Radio Shack. I have seen a Radio Shack store manager (Albany, California) say exactly that

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