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AT&T UNIX PC enthusiasts out there?

That reminds me. I need to revisit my Pi Pico based adapter in the near future. There's some software handshaking that occurs during boot that I'm not accounting for. If the mouse is moved before the graphic display appears the system won't respond to it at all. For now, just be careful not to move it during early boot. I'm sure it's something simple.
Are there build instructions / code available for your Pi Pico based adapter? I've got agentb's github repo for the arduino based adapter, and seen your pictures etc. but haven't found the details.
 
Yeah sorry I don’t have more complete documentation. I ended up just prototyping the mouse connection and didn’t package it up nicely like @shirsch did.
 
I am up and running with the MFM emulator. Forgot how long it takes to boot - we are really spoiled! Parts on the way for a PS/2 mouse conversion.

Has anyone tackled the RTC battery? Looks like it might be welded in, but I didn't want to mess with it too much (and was focused on getting the drive going.
 
Has anyone tackled the RTC battery?
Seems to be two types used, a large coin cell and cylindrical. Both soldered to board. Voltages are the same so can use either. I used a cylindrical, attached long wires from battery to board. Heat shrunk it and put it in empty slot so if in the future it leaks it won't damage the board. On my image I also have a date command to set year >= 2000. http://www.pdp8online.com/3b1/files/usr/local/src/
 
While I await mouse-building parts, I've noticed I get kernel panics if my RAM card is installed (have tried all slots). Is it possible to use the info in the panic message to suss out which memory chip(s) is/are faulty?

image0 (4).jpeg
 
It might be. Have you checked the system documentation to see if the panic dump text is described? However, the first thing I would do would be to take some non-residue contact cleaner to both the board and the internal backplane. Then, put the memory board on a flat surface (making sure you are grounded against static) and reseat all the DRAM chips by pressing down on them with your thumb. In other words, don't assume the worst (bad chip) until you've eliminated some of the common issues with older machines. Almost forgot: Check the jumpers on the board against the manual to see if everything is in the right place.
 
It might be. Have you checked the system documentation to see if the panic dump text is described? However, the first thing I would do would be to take some non-residue contact cleaner to both the board and the internal backplane. Then, put the memory board on a flat surface (making sure you are grounded against static) and reseat all the DRAM chips by pressing down on them with your thumb. In other words, don't assume the worst (bad chip) until you've eliminated some of the common issues with older machines. Almost forgot: Check the jumpers on the board against the manual to see if everything is in the right place.
If you really want to do it up right, you might want to buff the card edge with a fiberglass scratch brush and if your DRAM is socketed, removing them, dipping the legs of each chip into a shallow container to wet the legs with Deoxit(or equiv) and re-insert will likely solve connection isues now and help control corrosion in the future.
It used to be the case that you could get a chip tester that would do most 7400 series logic and RAM DIPs for $50-100, that looked like this https://www.aliexpress.us/item/3256801137410172.html
There are several DIY solutions around though, so one could just test chips. https://hackaday.com/2022/02/27/simple-dram-tester-built-with-spare-parts/
Of course, that assumes your RAM is socketed, which isn't always the case. If your ram isn't socketed, you can build an in-circuit tester or might be able to use the old HP in-circuit comparator tester widget.
 
you might want to buff the card edge with a fiberglass scratch brush
Unless its different that the one i have I wouldn't use that on plated card edge fingers. I use it for removing solder mask and rust. Seems like it would scratch through thin plating. Unix PC memory cards are pin and socket anyway so don't think you can use it.
 
Unfortunately the RAM isn't socketed, and I definitely don't have it in me to desolder 72 chips. Been reading docs and haven't found anything about the panic message format. I'm not sure if the diagnostic disk Memory Test will test expansion RAM but that's probably the easiest next step.

Card issue aside, grateful to have this old machine running again!
 
Unless its different that the one i have I wouldn't use that on plated card edge fingers. I use it for removing solder mask and rust. Seems like it would scratch through thin plating. Unix PC memory cards are pin and socket anyway so don't think you can use it.
Crisis Computers was a pretty well-known supplier of dec spares and the owner absolutely swore by a fiberglass scratch brush along the lines of the Bergeon 5948 for card fingers. Said it "repaired" a significant number of the boards he received as "bad".
It's seems a little aggressive and it's not something I use unless I'm concerned there is a problem, but I haven't noticed any damage and it does work to clean all but the most hopeless contact edges.
 
Curious what you consider an equivalent to be.
I've been skeptical of Caig's multi-colored magic formula products.
I'll have to dig around for the other stuff I used to use. It worked really well and was used by NASA BITD, so I assume it's banned because it destroys the environment or is wildly toxic.
I've been known to use Lear ACF-50 as a protectant for newly-cleaned contacts and been pretty happy with the results, once again though, I don't recall the non-mechanical oxide-remover I used in conjunction with it.
I might try this if I were shopping. https://www.3m.com/3M/en_US/p/d/b00034204/
As to the Caig line, I feel the base product is useful and suspect they decided to add some dye and change up the label to sell product, but they are all the same.
 
Phil's FreeBee emulator is great! I've spent a lot of time with the code and helped fix some bugs and make some enhancements. Definitely worth checking out if you want to play around with an emulated UNIX PC. There are two drive images linked from the github which help get up to speed without having to do a full system install.


MGR is very interesting and something I want to explore further. Is this something you used to use on UNIX PC? It requires the VIDPAL hardware mod that allows user writes to VRAM. However, there is a VIDPAL software emulator kernel driver which intercepts the MMU bus errors, and does the user read/writes to VRAM. That way MGR can be run once the vidpal kernel driver is running. It's slower of course but at least can be run. MGR "fix 4" for UNIX PC is pretty easy to find. But there was also a fix 5 which I have yet been able to track down:

The quickest way to try MGR is to use the mgr-demo.tar.gz:
How many people here own the real hardware?
 
Have a 3B1 and 7300. Were wife's first computers.

Repo doesn't have any changes in last two years. Were your fixes a while ago or have they not made it to the repo?
 
I also have a 3B1 and 7300. Haven't messed with them recently, but was hoping to make a PS2 keyboard to UNIX PC adapter as the keyboards are sometimes in short supply.
 
I have two 3B1s and a PC7300, plus a pile of peripherals. From memory: tape backup w/ controller, DOS-73 board, ethernet board, expansion chassis with interface, StarLAN interface and maybe a few other things I've forgotten. One of the systems was missing the rodent, so I wrote a little python program to run on a Pi Pico to convert from PS/2 to the AT&T protocol.
 
So, I was a VAR/ISV. I had some hardware and software fun bitd. You know you can port a lot of Mac's quickdraw to the s4... ;-) I sold off all my personal machines, but I admit, I miss that squeaky clackity chirp chirp.
 
I have the 3b1 with 60mb disk, ethernet, tape, and memory expander, and a tape drive out in the shed. Don't have the cable that connects the 7300 to the tape drive which is fine because I'm sure the tape drive needs major amounts of work
 
I have the 3b1 with 60mb disk, ethernet, tape, and memory expander, and a tape drive out in the shed. Don't have the cable that connects the 7300 to the tape drive which is fine because I'm sure the tape drive needs major amounts of work
That’s great you have an Ethernet card. And additional memory card. I have a copy of the tape backup service manual that I don’t think anyone has scanned in yet. Unfortunately I don’t have a scanner though. If anyone can scan, I can mail it to you so we can get it up on bitsavers.
 
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