[TUHS] Re: AT&T UNIX PC (7300) Teardown and Restoration

https://www.amazon.com/NOYITO-Module-Conversion-Arduino-communicates/dp/B07… is my go-to for when I need a simple one, though something like https://www.amazon.com/NOYITO-Module-Conversion-Arduino-communicates/dp/B07… 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 &lt;segaloco(a)protonmail.com&gt; 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 &lt;imp(a)bsdimp.com&gt; > wrote: > > > > On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS &lt;tuhs(a)tuhs.org&gt; 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… >> 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(a)atvetsystems.com < >> rob(a)atvetsystems.com&gt; 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 &lt;tuhs(a)tuhs.org&gt; 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(a)tuhs.org&gt; 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. >> >> >> >> >> >