TU58 problems

[Mark J. Blair]

On Jan 16, 2016, at 12:15, tony duell <ard at p850ug1.demon.co.uk> wrote:

> I had considered that, or one of the TU58 emulators that use SD cards or 
> similar but (a) I am trying to restore this VAX, not make a machine that runs
> VAX software and is not original and (b) I do have this moral objection to 
> using more components to load the microcode than in the rest of the machine.

I am in that same camp. I am presently using TU58 emulation to make progress on the rest of the system, but I do plan to try to get my original drive and tapes working in the future. Even if I immediately unplug it and plug an emulator back in, because I thoroughly distrust the tape cartridge design and I am not confident that any of my tapes are any good. I would like to make an SD card based emulator that clicks into place in one of the tape slots and the plugs into the console I place if the original drive, so it can be as unobtrusive and standalone as possible. 


> 
> AFAIK the TU58 interface (at least on the 11/730) can run at RS232 levels, you
> don't need a level shifter board.

Correct. Regular RS232 levels. There is at least one really short timeout in the console code that can cause trouble with some emulators running on some platforms, but I managed to hack around that in tu58em running on a Mac. I put together hardware to use a RasPi instead so the 730 doesn't need to be tethered to a laptop, but I haven't gotten that working yet. 


> This, alas, means I am not going to have 
> ethernet since AFAIK you can't run the cable through that odd cable tray thing on
> the 11/730.

I have Ethernet in my 730, though I don't have it working yet. My experience is that trying to route the round AUI cable through the bottom tray with the ribbon cables is doomed to failure, but the cable can instead be routed over the top of the cards, through openings in the power supply area, then along the folding gantry along with the power cables. I haven't gotten networking up and running on my VAX yet, and I don't yet know what combination of hardware, software and operator ignorance is causing it to not work.  I'm still pretty happy that I can boot VMS from either the R80 or RL02.