Thanks Roland.Good job! When I got my pdp8/f it worked after cleaning and a bit of the standard tlc. After that it failed four times again, every time something else. I ending up replacing 4 ttl chips. Now it works stable in the few years that I've got the machine. But Restoring an old machine now will not mean that it will work for ever... I have had tested and working spares, and when I needed it guess what... It broke down while sitting in an esd bag... So this old stuff will keep you busy
Common problem when switch contacts get dirty. Can get some other strange behavior also since the edge triggers the cycle but the level is fed to logic so if it goes away strange things can happen.
There are three designs I need to debug, which all use the same board and CPLD pin-out. The serial is fairly simple, but the extended memory control uses all 64 of the CPLD pins. I'd like to get to a single setup with the cabling and the logic alanyzer programming the same for all three, since it seems likely that I'll be debugging for a while.
Can't you fully simulate your design using ModelSim (or similar) to avoid (or at least limit) the debugging on the bench with a logic analyser?
Possibly. However, doing that implies a learning curve for ModelSim, and presumes that I also fully understand how to model the Omnibus. My previous experience with ModelSim was that it was easy for me to get models to simulate, but hard to get models that actually ran on the hardware. I can only assume meant I somehow understood the hardware imperfectly.
If you have implemented your design in VHDL, then I would be interested in seeing the code.
It's Verilog, as extracted from a TTL schematic. I can send it to you if you're still interested.
I have used VHDL for reasonably complex stuff before but ignored Verilog as it was more limited back when I started with FPGAs. Clearly Verilog has improved a lot since but as VHDL works well for me so I felt there is no point in learning yet another language doing the same.
Our minds are on the same track. I also ordered switch handles fabricated in the same PA12-HP Nylon. The first batch was grey because it seemed it would contrast better with the black plexi panel. I learned that the "natural grey" seemed to absorb a slight amount of grease from my fingers. Perhaps I shouldn't eat lunch while operating my 8/E, haha. In that first order of switches, JLC by mistake made one of the switches black, which was kind of interesting for me. The second batch, which I just received recently, are all in black PA12-HP Nylon.
I agree, the Nylon is very strong. Both the grey and black handles that I had built are Vince's design with the nylon pins. The switches have gotten a lot of use because I don't yet have a bootloader board.
I agree completely. My goal is to have the printed part rather than tinkering with the 3D printing process, so it's nice to have someone else be concerned with process control and quality.
