Looking for a M8330 or a couple of SN74194's

Hi Having worked for DEC for a number of years I'm used to the odd logic symbols. They do explain them in the manual. I don't use a CAD system but something much more useful. Visio. Define a DEC logic symbol once, add connection points in the right places, drop as many copies as you need, join connection points and print on A0 paper. Modify drawing as much as you like and print a new copy each time. Iv'e moved the boards back a bit and as soon as I get a few mins I'll see if I can spot why it won't write to memory. Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Tony Duell Sent: 01 April 2008 20:31 To: cctalk at classiccmp.org Subject: Re: Looking for a M8330 or a couple of SN74194's All Omnius slots are the same, and in an 8/e backplane, AFAIK all slots are plain Omnibus. The only time the top connectors are used on the M8330 is if you have the EAE board set installed, I think. If you do, take it out for the moment (you don't need it when trying to sort out a timing generator problem). You can then put the M8330 in whatever slot you want. An extender board is useful, but by no means essential :-). Another trick that's worked for me in the past if I can't re-arrange the boards and don't have an extneder is to solder a hnadful of wires to useful testpoints on the board and put it back in the cardcage. Then probee the free ends of the wires (make sure they don't short to anything!). Normally 2 or 3 iterations of doing that will get me to the faulty chip. DEC scheamtics have the odd error on them (I've heard it claimed said errors are deliberate, either to stop the machine being copied, or as copyright traps on the diagrams themselves). They're also somewhat unconventionally drawn (flip-flops may appear to have 4 outputs!), but I've got used to them. I must say that if I need to re-draw a sechematic, I use pen and paper, not a CAD system... -tony