One more thing ... to be fair to Warner: I believe that adding the F/M version of this: https://www.amazon.com/dp/B082VM3SJG should create the traditional electro-mechanical version of a true RS-232C with the board he suggested (and like him I have a few boxes of these things in my basement). I just used Amazon for reference, they used to be sold by most computer stores. ᐧ ᐧ On Wed, Jan 4, 2023 at 3:48 PM Clem Cole wrote: > Matt - send me an email offline if you need more help. Warner speaks the > truth - although he left out some wizardry that has sadly been lost for > ages. > > The first board he offers will create the interface that an IBM PC/AT > created which was originally not a standard either (eventually EIA back fit > it, in RS 232-E IIRC, but RS-232 C which is what the UNIX PC's interface > was defined does not use it]. > > From your email, it looks like AT&T out a standard Data Terminal Equipment > (DTE) pinning on the back of that system (which would make sense). That > means it should be a >>male<< 25 PIN (i.e. male) D style 'B-sized' > connector with pins 2 (TX), 4 (RTS), 20 (DTR) being driven; and pins 3 > (RX), 5 (CTS), 6 (DSR), 8( DCD), 22 (RI) as inputs. With Pin 7 being the > signal reference ground and Pin 1 being the frame ground (often N/C - but > do not short to 7 on your board) > > The signals should swing from +3 volts to up to +30 when assert as a > spacing time, and -3 to -30 volts marking time. However, anything over +/- > 15 volts is unusual, but the interface is required to accept it. > Frankly, +/- 9 volts is most likely what you will see with the 1488/1489 > driver pairs which were the preferred chips used in those days. > > Amazon does not seem to sell an equiv that spits out real RS-232C using > the D connector, but rather this PC/AT variant, so you will need to make a > cable -- the good news is they do sell: > https://www.amazon.com/Kentek-Female-Serial-RS-232-Adapter/dp/B07KVFM4MS > > My suggestion would be to use this on you Mac/WIndows or Linux box: > > https://www.amazon.com/Sabrent-Converter-Prolific-Chipset-CB-DB9P/dp/B00IDSM6BW > connect it to the cable I just mentioned -- at that point your > Mac/Windows/Linux Box will look like a Proper 'terminal' as the being > expected then if needed > > > a 25 pin null modem between it that the 3B1 such as: > https://www.amazon.com/Monoprice-DB25-Null-Modem-Adaptor/dp/B001VL8RK2 or > whatever one you need M/M, M/F -- etc... > > > > On Tue, Jan 3, 2023 at 7:58 PM Warner Losh wrote: > >> >> https://www.amazon.com/NOYITO-Module-Conversion-Arduino-communicates/dp/B07BJJ1T5G >> >> is my go-to for when I need a simple one, though something like >> >> >> https://www.amazon.com/NOYITO-Module-Conversion-Arduino-communicates/dp/B07BJJ3TZR >> >> might work better for your setup if you just have more of the TTL gear >> than RS-232 gear (I have way too many old RS-232 cables because I never >> know when I'll need them again...) >> >> Warner >> >> On Tue, Jan 3, 2023 at 5:46 PM segaloco wrote: >> >>> Nope, unfortunately I only know as much as is needed to plug into the >>> GPIO RX/TX/GND working on single boards. I wouldn't be surprised if my >>> assumption I just run these pins into the D-25 in the right holes is >>> bunk...but that's how we learn sometimes. Once I move I should be able to >>> setup a proper work bench where I can tinker on this sort of thing more >>> intentionally rather than haphazardly. So perhaps a silly question for an >>> expert but a valid one for me. I'll chase that angle and see if it bears >>> fruit. >>> >>> - Matt G. >>> ------- Original Message ------- >>> On Tuesday, January 3rd, 2023 at 4:40 PM, Warner Losh >>> wrote: >>> >>> >>> >>> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS wrote: >>> >>>> I'd love to get my hands on a 3B2 someday, this'll be cool if I can get >>>> it going but that'd be a much more robust machine. >>>> >>>> I'm starting to suspect if there isn't any sort of boot ROM that spits >>>> out commentary on the UART and that doesn't get flexed until UNIX is up, I >>>> may not be able to get very far. I referred to >>>> http://bitsavers.trailing-edge.com/pdf/att/3b1/999-809-010IS_UNIX_PC_Remote_Access_1986.pdf >>>> for the serial settings and it appears: >>>> >>>> 9600 baud, 1 stop bit, no parity, 8 data bits >>>> >>>> And the relevant pins >>>> >>>> Pin 1 - GND >>>> Pin 2 - RX >>>> Pin 3 - TX >>>> Pin 4 - RTS >>>> Pin 5 - CTS >>>> Pin 6 - DSR >>>> Pin 7 - GND >>>> Pin 8 - DCD >>>> Pin 20 - DTR >>>> >>>> So I've plugged my USB-TTY GND/RX/TX into the relevant pins and setup >>>> the necessary tty settings. The manual then suggests if running null modem >>>> mode to short pin 4 to 5 and then pins 6, 8, and 20 together, presumably >>>> omitting any need for modem signalling from the remote machine, doing basic >>>> serial RX/TX. Unfortunately even with all of this bypassing I get nothing >>>> out of the RS-232 port. What I don't know is if I could even expect >>>> something or if this is unlikely to bear fruit whether the hardware works >>>> or not. In any case, if I do get this thing running I'll have a writeup for >>>> folks afterwards. If not, then hopefully I can figure out something useful >>>> to do with this thing rather than junking it. >>>> >>> >>> Silly question... did you level shift to RS 232 levels? You likely >>> did... but if not... >>> >>> Warner >>> >>> - Matt G. >>>> ------- Original Message ------- >>>> On Tuesday, January 3rd, 2023 at 3:53 PM, rob@atvetsystems.com < >>>> rob@atvetsystems.com> wrote: >>>> >>>> Hello Matt, >>>> >>>> I’ve got one of these in my garage. I bought it about twenty years ago >>>> as a working system but when I got it home I noticed that the hard disk >>>> wasn’t connected but at some point I’d like to get it and my 3b2/300 >>>> working. >>>> >>>> Regards, Rob. >>>> >>>> On 3 Jan 2023, at 23:27, segaloco via TUHS wrote: >>>> >>>> And here are some pictures of the guts. >>>> >>>> https://imgur.com/a/E1ioxZl >>>> >>>> Various bits inside date this to late 1985. The good news is it at >>>> least turns on, but that's about as far as I've gotten with it. The display >>>> never turns on, nor do I hear any sounds indicating it tries to start the >>>> CRT. The fans kick on and there it stays until I turn it off. I plugged in >>>> a USB-TTY to pins 2, 3, and 7 (RX/TX/GND) and listened at 9600 baud 8 bit 1 >>>> stop no parity and got nothing. Swapped the RX/TX, still nothing. Of >>>> course, that's all predicated on the assumption there's something there to >>>> even interact with. I have little faith that whatever UNIX install was on >>>> this is extant. Additionally, it didn't come with a keyboard, so if there >>>> was some futzing with key combos that would trigger some sort of UART over >>>> those lines, I can't do that. I wonder if there are some contacts inside I >>>> can just poll for activity with this serial connector, not sure how safe >>>> that is... >>>> >>>> Anywho, the CPU has a bit of corrosion on the surface, not sure how >>>> that bodes for the innards, but this is in kinda rough shape either way. I >>>> hope I can salvage it but if not, I'm going to at least do some study on >>>> the CRT particulars and see if I can extract and keep the monitor from it, >>>> been wanting a smaller CRT to have around for a while. >>>> >>>> - Matt G. >>>> ------- Original Message ------- >>>> On Tuesday, January 3rd, 2023 at 12:20 PM, segaloco via TUHS < >>>> tuhs@tuhs.org> wrote: >>>> >>>> Good day everyone, just starting a thread for yet another project I'll >>>> be tinkering on over time. Picked up a (presumably broken/untested) 7300 >>>> off eBay to at the very least tear down and get some good pictures of and, >>>> with some luck, perhaps get working again. >>>> >>>> https://imgur.com/a/CExzebl >>>> >>>> Here are some pictures of the exterior for starters. I'll update this >>>> thread when I've got pictures of the guts and also with any info I can >>>> glean regarding whether this might be salvageable. The rust on the back is >>>> pretty nasty but I've seen older/worse start up just fine. >>>> >>>> - Matt G. >>>> >>>> >>>> >>>> >>>> >>>