[rescue] Sun 3/50 scsi boot string

[Chris Hanson]

On Dec 26, 2022, at 11:06 AM, Kurt Nowak via rescue <rescue at sunhelp.org> wrote:

> Yes, driving the display on my 3/50 will be another little side project. I got some hints from others here and ordered a DB-9 breakout connector in order to mod a VGA cable to make a custom interface dongle. I want to avoid having to get a CRT monitor as space is always a premium. The Dell 2007fpb I have seems to drive a plain bwtwo (13W3 version FB), so I don't see why I can't get the 3/50 to work on it as well. Thoughts? I know - not very "vintage" but I have to find a happy medium.

If your 3/50 uses ECL rather than TTL monochrome, you can adapt one of the Atari TT high-resolution video adapters for it. The Atari TT High-Resolution Monochrome Monitor was essentially identical to the Sun ECL monochrome monitors, down to the pinout on the monitor end of the cable; the TT has a VGA connector but something in the connector says that the ECL display is connected.

So you’d just wire the Sun DE-9 *output* pinout to the TT VGA *input* pinout on the adapter, and then plug your LCD into the “regular” VGA *output* pinout on the adapter.

All the adapter really does is take the ECL differential video signal and use it to produce an RS-170 video signal (0 to +0.7V peak to peak); the sync signals should work as-is because they’re TTL. It should barely require any electronics, though what it does require needs to operate at a couple hundred MHz due to the bandwidth that 1152×900 (or 1600×1280!) video demands. So a 0.7V supply for the signal to modulate and a transistor or two to do the modulation based on the ECL input should be it.

  — Chris