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

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

[segaloco via TUHS]

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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.

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

[segaloco via TUHS]

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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.

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

[segaloco via TUHS]

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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.

- 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 <tuhs@tuhs.org> 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.

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

[Warner Losh]

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On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.
>
>
>
>
>

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

[segaloco via TUHS]

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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 <imp@bsdimp.com> wrote:

> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.

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

[Warner Losh]

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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 <segaloco@protonmail.com> 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 <imp@bsdimp.com>
> wrote:
>
>
>
> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.
>>
>>
>>
>>
>>
>

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

[Ori Idan]

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First check using a scope that you have clock signal (on the PCB) this will
show if the hardware works or not.
As for the serial port, test what level do you have there, I'd expect a
level of around -10V

-- 
Ori Idan CEO Helicon Books
http://www.heliconbooks.com





On Wed, Jan 4, 2023 at 2:58 AM Warner Losh <imp@bsdimp.com> 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 <segaloco@protonmail.com> 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 <imp@bsdimp.com>
>> wrote:
>>
>>
>>
>> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.
>>>
>>>
>>>
>>>
>>>
>>

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

[Clem Cole]

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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 <imp@bsdimp.com> 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 <segaloco@protonmail.com> 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 <imp@bsdimp.com>
>> wrote:
>>
>>
>>
>> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.
>>>
>>>
>>>
>>>
>>>
>>

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

[Clem Cole]

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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 <clemc@ccc.com> 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 <imp@bsdimp.com> 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 <segaloco@protonmail.com> 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 <imp@bsdimp.com>
>>> wrote:
>>>
>>>
>>>
>>> On Tue, Jan 3, 2023, 5:30 PM segaloco via TUHS <tuhs@tuhs.org> 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 <tuhs@tuhs.org> 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.
>>>>
>>>>
>>>>
>>>>
>>>>
>>>

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