dfnr2
Experienced Member
I've been working on restoring my Sol-20, and get to the point of having a boot prompt, but when I attempt to type commands, I'm observing incorrect behavior.
On booting, the UPPER CASE light is on, but the alphabet keys give non-ASCII characters. UPPER CASE cannot be turned off.
SHIFT LOCK toggles the local LED as well as the SHIFT LOCK LED. With SHIFT LOCK engaged, alpha keys give (mostly) the correct values, but numeric keys don't.
With SHIFT LOCK off, the lower case keys give wrong chars, but consistently mapped.
RETURN doesn't work, and neither does CTRL-M. LF and CTRL-J do the same thing, which is generate an "?" error message and go to the next line, except every once in a while it also home the cursor, which never makes it to the bottom of the screen. "0", "@", and spacebar all act like a Return.
I might have suspected my ROM images, but the original SOLOS module behaves the same as the replacement module. The screen clears just fine on startup, and the prompt displays properly.
I plan to look into it when I have a little time. If there's a stuck bit, the issue could be anywhere from the analog multiplexers through the RAM or the PROM. Both the 2101 and 74S287 might be candidates for statistically most likely to fail, but I'll have to poke around to get a clearer picture of what's going on.
Has anyone had a similar experience? Has anybody dumped a working PROM?
Dave
On booting, the UPPER CASE light is on, but the alphabet keys give non-ASCII characters. UPPER CASE cannot be turned off.
SHIFT LOCK toggles the local LED as well as the SHIFT LOCK LED. With SHIFT LOCK engaged, alpha keys give (mostly) the correct values, but numeric keys don't.
With SHIFT LOCK off, the lower case keys give wrong chars, but consistently mapped.
RETURN doesn't work, and neither does CTRL-M. LF and CTRL-J do the same thing, which is generate an "?" error message and go to the next line, except every once in a while it also home the cursor, which never makes it to the bottom of the screen. "0", "@", and spacebar all act like a Return.
I might have suspected my ROM images, but the original SOLOS module behaves the same as the replacement module. The screen clears just fine on startup, and the prompt displays properly.
I plan to look into it when I have a little time. If there's a stuck bit, the issue could be anywhere from the analog multiplexers through the RAM or the PROM. Both the 2101 and 74S287 might be candidates for statistically most likely to fail, but I'll have to poke around to get a clearer picture of what's going on.
Has anyone had a similar experience? Has anybody dumped a working PROM?
Dave