Still Looking For AT&T 3B2 Internals Docs

Seth Morabito lists at
Mon Mar 6 17:24:16 CST 2017

* On Mon, Mar 06, 2017 at 03:54:17PM -0600, Jerry Kemp via cctalk <cctalk at> wrote:
> Very interesting.  I didn't start wearing a Unix hat till 1989-1990 time
> period.  Aside from the ATT 3B2, my only other exposure to SysVR3 Unix was
> thru Banyan Vines.
> Banyan Vines sat on top of SysVR3 Unix, and we used a lot of Banyan Vines.

Very interesting, I wonder if I could learn anything from Banyan Vines?
I recall it on the PC, but I didn't realize it was on SVR3 as well.

> Back on topic, I guess I had not understood your request enough, I had
> though you were needing specific hardware and CPU information.  Did not
> realize that there were software/SysVR3 questions you were still asking.

Oh, I definitely do still need specific hardware information. The "big"
chips (the CPU, MMU, DMA controller, floppy & disk controllers, UART,
etc.) are thankfully very well documented! But the rest of what makes up
the 3B2/400 system board is not documented anywhere but inside the SVR3
source code. 

Also, if I ever hope to emulate the cartridge tape controller or the
extended serial ports, SCSI, or Ethernet cards, I'll need yet more
information. I don't have the source for those drivers, so I have
absolutely no idea how they operate.

> Jerry Kemp


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