On Thu, 27 Feb 2020, Adam Thornton wrote: That would be something like a DD-52P (certainly not a DB-52P!). Well, Digikey seem to have them: http://www.digikey.com/product-detail/en/itt-cannon-llc/2DB-52P/2DB-52P-ND/… No photo, though... -- Dave

Yeah, 0.075" pin centers, does appear to be the ITT Cannon part. Now what experiment used them, and _why_ (I mean, surely 68-pin SCSI would have done the trick as well and been muuuuuuch cheaper), I don't know. Adam On Thu, Feb 27, 2020 at 6:37 PM Lawrence Stewart <stewart(a)serissa.com> wrote:

On Fri, 28 Feb 2020, Dave Horsfall wrote: Oops - I misread what you wrote; apologies... -- Dave

A RocketPort multi-serial sounds really, really likely for an astrophysics data collection instrument. Thank you! Mystery probably solved! The 8250 was unbuffered or maybe had a 1 byte buffer, the 16450 had a 1-byte buffer, the 16550 had a 16-byte buffer. I remember vividly how much better my life got when I got 16550 serial ports for my '386. Adam On Fri, Feb 28, 2020 at 7:12 AM Clem Cole <clemc(a)ccc.com> wrote:

On Fri, 28 Feb 2020, Adam Thornton wrote: I remember the RocketPort; we used to call it the OctopusPort... The 16550 series was an utter balls-up, with broken silos etc. This is from http://en.wikipedia.org/wiki/16550_UART : The original 16550 had a bug that prevented this FIFO from being used. National Semiconductor later released the 16550A which corrected this issue. Not all manufacturers adopted this nomenclature, however, continuing to refer to the fixed chip as a 16550. According to another source, the FIFO issue was corrected only in the 16550AF model, with the A model still being buggy. (The C and CF models are okay too, according to this source.) The 16550AFN model added DMA transfers. You had to pay careful attention to the manufacturer and the suffix. -- Dave

On Fri, Feb 28, 2020 at 4:28 PM Dave Horsfall <dave(a)horsfall.org> wrote: DZ-11 sucked... for a number of reasons, the SW issue being just part of them, but they were short pinned and really did not do modems well, particularly high-speed ones like the Trailblazer. As you said, you could make them work, but why bother? Unix folks figure out the best idea was to use the Able DH/DM - cheaper, only one unibus slot for 16 ports (as opposed to 2 for the DZ), fully wired on the DB25 end, hardware flow control and just worked better in that is will DMA. What was not to love... On my long 'todo' list has been to work with Mark to get SIMH to properly support the DH in his emulation. He has some stuff in there, but last time I checked (about a year ago) it still was not right, which is a sort of a shame. FWIW: One of the guys behind DZ (who I will leave nameless) also screwed up the first serial port on the Masscomp MC/500 after he left DEC. I got there too late to fix it in the first version of the CPU board. So it was not fixed until I tore him a new one and educated him on how RS-232 actually worked (I was the first lead for the data com group as well as 1/2 the OS team). I never quite understood why HW folks often though of the serial port as '3-wires' -- sigh.

Best I could tell, the major intended purpose of the secondary circuits was to implement autodialer, especially when those handshaking signals on the primary were down because there was no connection, so you couldn't do anything through them yet. Was there anything else in mind during the spec process? De

Could it be because they all started with current loop tty interfaces? Most of the old DEC guys started with teletypes. Having struggled with a breakout box and different mini and micro vendors implementations of serial ports... Ugh. And in three-wire the use of Xon-Xoff varied big time. No standard was the standard. IIRC the IBM Series/1 had a different 9pin layout than the PC/AR. Why? At least DEC was reasonably consistent until they moved too the Vax modified RJ design. I am still amazed at the number of current loop DZ11s interfaced via 4 pin square phone jacks on a wall at the back of the machine room. Seemed like 100 lines of VTs and Dec writers at one hospital in 1985. As far as the DZ... One thing I saw at Dec to improve things was the Comm-iop DZ which managed the DZ from a KMC11 (IIRC). I think it was a CSS option on PDP11s.... Bill Sent from pechter(a)gmail.com -----Original Message----- From: Clem Cole <clemc(a)ccc.com> To: Dave Horsfall <dave(a)horsfall.org> Cc: Computer Old Farts Followers <coff(a)tuhs.org> Sent: Fri, 28 Feb 2020 16:44 Subject: Re: [COFF] 52-pin D-Sub? On Fri, Feb 28, 2020 at 4:28 PM Dave Horsfall <dave(a)horsfall.org> wrote: DZ-11 sucked... for a number of reasons, the SW issue being just part of them, but they were short pinned and really did not do modems well, particularly high-speed ones like the Trailblazer. As you said, you could make them work, but why bother? Unix folks figure out the best idea was to use the Able DH/DM - cheaper, only one unibus slot for 16 ports (as opposed to 2 for the DZ), fully wired on the DB25 end, hardware flow control and just worked better in that is will DMA. What was not to love... On my long 'todo' list has been to work with Mark to get SIMH to properly support the DH in his emulation. He has some stuff in there, but last time I checked (about a year ago) it still was not right, which is a sort of a shame. FWIW: One of the guys behind DZ (who I will leave nameless) also screwed up the first serial port on the Masscomp MC/500 after he left DEC. I got there too late to fix it in the first version of the CPU board. So it was not fixed until I tore him a new one and educated him on how RS-232 actually worked (I was the first lead for the data com group as well as 1/2 the OS team). I never quite understood why HW folks often though of the serial port as '3-wires' -- sigh.

below... On Fri, Feb 28, 2020 at 5:26 PM William Pechter <pechter(a)gmail.com> wrote: Very possible... RS-232A/B/C was DB-25 P for the DTE (terminating equiment - a.k.a. terminal) and S for DCE (communications equipment - a.k.a. modem). It was standardized. At one time, I (sadly) could quote the paragraph number.... Then in 1978 #$%^& Lear Seglier put a DB-25S on a DTE (terminal). They were the cheap terminal vendor and all hell broke loose. The PC/AT used 9 pin because the back of the unit was small and -- well there could because IBM said so .... But at least the IBM engineers kept to Plug and Sockets from the standard. I did not know the Series/1 used 9 pin. Learn something new. Indeed - that was a huge issue - the modified RJ block -- sigh...

The John McNamara book still seems to be around. Great reading. I worked for DEC in Monmouth and Mercer counties and one night stole all the Vax 11/780 kits from DEC Holmdel. Boy were they pissed. However, I had a critical outage at the FBI at Fort Monmouth with two hour response so I didn't drive an hour to my Princeton office. 8-) I had Holmel's keys and alarm codes so I left them an IOU and headed to the site. Holmdel was 15 minutes from the site but their techs were dedicated to telco only... So their parts took a trip. The DEC folks at the labs and AT&T sites were treated like royalty compared with us regular commercial business groups. They had the best training... newest machines... If they found a pdp8 or 11/23 and had repair issues - - they had us called. We saw more wierd like the Vax 11/782 that couldn't back up because it was sold without enough memory in the main (or attached cpu) to run standalone backup. I had to go in on Saturday to move a memory board between CPUs. I think Field Service donated a board to RCA Semi finally. That was a dumb machine design. I spent years with a lot of computer companies and RS232 interfaces were easy as long as there was only one vendor. If you see how Pr1me or Hewlett Packard dealt with the serial ports... I used to be the guy who at the most desperate would get Kermit over a 3 wire interface to allow data transfer between different systems. Or UUCP on ms-dos... Something about jack of all trades. Bill Sent from pechter(a)gmail.com -----Original Message----- From: Clem Cole <clemc(a)ccc.com> To: Dave Horsfall <dave(a)horsfall.org> Cc: Computer Old Farts Followers <coff(a)tuhs.org> Sent: Fri, 28 Feb 2020 17:21 Subject: Re: [COFF] 52-pin D-Sub? On Fri, Feb 28, 2020 at 4:58 PM Dave Horsfall <dave(a)horsfall.org> wrote: That's not true. All our UNIX systems at UCB and CMU had DEC field service on them and we had lots of non-DEC HW, including memory, disk and disk controllers. Funny, the DEC knew we could swap memory chips on the National Semiconductor memory board for the Vax. Which we could not do with the DEC boards, they had to be swapped. The same was true at BTL, in fact and at Bell, there were DEC folks on-site. They might occasionally gripe, but we used to joke about it. It probably helped in all these places we had more than multiple systems and the field offices knew better. If we called, it was busted. Maybe you never saw a serial RJE station or I suspect a serial line that was fully synchronous running one of the IBM protocols. That was sort of where I started to learn in the late 1960s. I saw IBM systems before I saw the DEC ones and IBM used all the wires. Eventually, I got a copy of the wonderful DEC press book from John McNamara, called "Technical Aspects of Data Communications." Then I learned about UNIX, which came from AT&T which used all that stuff in their modems and data communications gear.

One thought I had for the 52 pin D-sub were the two 50 pin Pertec tape interface cables in some "cabinet kit" packaging for under floor. Saw this at Fort Monmouth Cecom on an 11/750 from a military project for early office automation on System V Unix based off of 2.x Unix work at Hanscom AFB called Lonex (if I remember the acronym). Bill Sent from pechter(a)gmail.com

On 2/29/2020 8:12 AM, emanuel stiebler wrote: You technically haven't lived until you use an acoustic coupler, a cassette tape recorder and a wire tap to record 300 baud modem tones as you type out files on a PDP-10 somewhere... And then play that tape back to your own computer and that same modem, and save it to floppy. It's how I saved LOGO.MAC from somewhere on the ARPANET back in the early-to-mid 80's. ;) art k.

On Fri, Feb 28, 2020 at 6:40 PM William Pechter &lt;pechter(a)gmail.com&gt; wrote: I know some of the story having known some of the players and lived a little of it, but I do not claim to know all of it. So I might be able to fill in some holes, but there is still plenty missing from the complete story. First, remember RS-232 is an ECMA spec for connecting communication gear to data gear. It's not so much about sync/async as it dealing with the phone systems in the US and Europe and how to interface computer gear to it. The driver of the spec was building and connecting RJE-like systems for banks and financial institutions, airline terminals, *etc*. to connect to a central (mainframe) computer. This is why it uses terms like "Data Communications Equipment" and "Data Terminating Equipment" - as opposed to modems, computer terminals, hosts and the like. Different systems vendors had different ways of thinking about the computer they were selling and how people would interface with them. And you can see the differences in the choices they make in gear like the peripherals that they interface at the time. The AT&T Teletype Model 28 (https://en.wikipedia.org/wiki/Teletype_Model_28 circa 1953 intro, 5-bit BAUDOT code, current loop) was the standard terminal on DEC systems for many years. Gordon Bell invented (patented) the UART to talk to it for the PDP-1 (maybe it was the PDP-6) sometime in the early 1960s. What I do not know/understand is what was the work he did at DEC and what when he had left to be a CMU prof. I was >>under the impression<< the patent was granted during his CMU time; but I had thought DEC originally built them as FLIP-CHIPS for the PDP-6. Then in 1963, 7-bit ASCII was introduced. IBM and AT&T were to two biggest firms behind it (remember that the IBM System 360 was supposed to be an ASCII system and has a lot of support for ASCII in its ISA; but due to the OS SW being late that stayed with their earlier BCD – creating EBCDIC - read Fred Brook's "The Mythical Man-Month <https://en.wikipedia.org/wiki/The_Mythical_Man-Month>" for the details). However AT&T, GE and DEC did switch to 7-bit ASCII pretty much as soon as they could. The AT&T/Teletype Model-33 ( https://en.wikipedia.org/wiki/Teletype_Model_33 circa 1963 intro, 7 bit ASCII code/current loop, but lacked shift key on the keyboard) was introduced soon thereafter and that became the standard terminal (7-bit byte, plus parity and 3 bits worth of start/stop -- 11 serial bits per transmission). My memory is that AT&T did not make sell an ECMA RS-232 version, but the aftermarket had a ton of converters between the current loop interface at the ECMA standard. So at the time, you have IBM using primarily synchronous interfaces, while AT&T (Teletype) used asynchronous. IBM liked sync because of the fact that it needed no wasted start/stop bits. They liked 1/2 duplex because their devices were primarily going one way at a time. In the 60s, IBM's big business has them connecting RJE stations and they would only much later do 1/2 duplex synchronous* terminals*. DEC was more interactive much sooner, used Teletype's and thus was async and full-duplex. I was also under the impression (*i.e.* once was told) that Western Digital obtained a license to make the UART as chips but it was never completely clear to me who held the patent (CMU or DEC) *i.e.* who/how WD got the license from. But after the chips appeared, DEC would buy those chips from WD for things like the DL/KL-11's and DH-11 interfaces and I think they made something like the DL11 for the PDP-8. If you look at the schematics for the early serial ports for the PDP-11, they are all using the same WD chip. Soon after the UART, WD also starts making a USRT, which (the best I can tell) they seem to be selling to IBM and the com vendors for IBM gear. I personally never programmed them, but they are in an old WD book I once had (may still). I remember seeing them in some Gandalf gear in the mid-70s besides the IBM gear, but I don't known/remember much more. In the early 1970s, CMU used the same WD UART chips as DEC was using in the DL-11, but had designed their own serial board, which we called the ASLI (there were other differences but mostly the SW could not tell the difference). Nat Semi was a second source for WD at some point in the late 1960s, and by the early 1970s, they started to design there own UART (as was pointed out eventually they created 8250 and it's follow ons). I'm not sure when Intel and Moto started to make them, but I think both the 8080 and 6800 families had UARTs chips. MOS Tech did not originally, although later when Rockwell became their second source, a UART for that family appeared too. At some point in the early 1970s, the first USARTs start to appear. I was under the impression, WD was the origin of them, but I do not know. By the time of the 16-bit micros, however, many of the better serial interface chips could be either synchronous or asynchronous under program control. With the 16-bit chips, a Zilog USART chip was fairly popular at one point from Macs to UNIX boxes. As other pointed out, because of the PC/AT the Nat Semi 8250 stuck around as it had ended up are part of the 'PC support chip family', even though it was a bit of dog and notorious for dropping characters at high speeds. For completeness, the Unix folks at BTL used the Teletype Model 37 ( https://en.wikipedia.org/wiki/Teletype_Model_37 ß 1968 intro, 7 bit ASCII code, full U/L case ) as their native printing terminal. IIRC the ASR-37 had an RS-232C option as well as a current loop one from Teletype as the industry had pretty much dropped off of the current loop standard by then. Interesting side note, the AT&T/BTL programmers often did not have 'hardwired' lines in their offices, but used modem (there was the phone company of course).