I received an e-mail from someone who noticed that I was obtaining a lot of PDP-8 documentation on e-bay.  He inquired if I might be interested in some PDP-8 gear.  There was bunch of equipement that we talked about but he never mentioned an 8/L.  Once I got to his place though, tucked on a corner shelf was an 8/L.  It was a bit sorry looking (most of the switch handles had been "scavanged").  I decided that it needed a new home...mine!

I really didn't know what I had, because he hadn't done anything with it and it's condition was pretty much unknown (other than one of the modules had a tag on it -- not usually a good sign).  When I got it home (along with all of the other stuff), I put it in a rack.  I powered it up and noticed that all of the switches are a bit "unreliable".  Many (like the load address and start) required more than a couple of tries before it would be recognized.  I'm sure some contact cleaner should work ok.

I tried loading some patterns in to memory to see how bad things were.  To my suprize most things worked except that bit 3 (remember PDP-8's number their bits like IBM does...most significant bit is 0) was stuck on.  A little bit of investigation noted that the bit could be zero, but when read a second time, the bit was on.  This is a familiar problem from a previous system.  It's a failed inhibit driver.  Looking up in the maintenance manual discovered that it was a G228 in position A23.  Swapping it with a G228 in position B23, saw the stuck bit move from bit 3 to bit 7 (as predicted).  Swapping out the G228 for another one yielded success.  I entered a small little program to see if the "L" would execute instructions and success!

Here's the front panel.

Here's the backplane with gobs of flip-chip modules.