DECstation 220 Now Getting Corrupted Video

I spent a bit of time today going over the leak-damaged area of the DECstation 220 looking for damaged tracks. I found a few pins on some of the chips that seemed to be disconnected and fixed them. In doing so the beep on startup has become intermittent, but I now get a video signal!

Video Pattern

Pattern now displayed by the DECstation 220

I believe patterns like this usually indicate some kind of memory problem. So I checked the DRAM and the Video RAM. The DRAM sees some write activity right after powering on the machine, but then the activity stops. For some reason the Paradise VGA chip never seems to write anything to the Video RAM.

This entry was posted in Retro-Computing and tagged . Bookmark the permalink.

1 Response to DECstation 220 Now Getting Corrupted Video

  1. Pingback: DECstation 220 Progress and Failure | Rob's Old Computers

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s