LA120 PSU: 555 timer?

Do you have the 555 data sheet? It _must_ be on the web somewhere, but I've never looked for it as I have at least 2 versions on paper. The 555 data sheet shows a component level schematic of the chip, and it's not that hard to follow. It also shows the standard applicaiton circu The instruments I used to use most when repairing calssic computers were the multimeter and a simple logic probe. The latter, sued with thought, can detect a laot of problems (it would be useful here to see if that trigger input is toggling, for example). Hower, I do find a good (if old) 'scope and a logic analyser to be very useful. The latter is important if you are working on the older, mostly-TTL-built machines as you are. Now, I use a multimeter and the HP LogicDart. The latter takes the palce of the logic probe, and is also a 3 cahnnel logic analyser, which is enough for a lot of things. Still use the 'scope and a larger LA when I need them, of course. -tony