My first project would have been a reasonably priced Gravitar that played blind. I thought it was pricy for a project... it wasn't. I thought fixing a vector would be too much of a challenge for a first project.... @andrewb showed me otherwise...
But I'm over it...mostly. But when I see one...
I have a RAM failing the memory test on an Outrun project and hit a wall so I thought I'd throw what I'm seeing out here in case anyone has some ideas.
Below is what I am seeing. The red trace is one of the data lines on the shared data bus between 2 EPROM, 2 RAM, and at least 3 bus...
Holy shit dude, I thought you were only donning the hat, whip and jacket.... I didn't realize that was the whole ensemble down to the f-ing Zippo. Maybe you made that distinction, but it was Halloween, at least 9PM, and I may have had one or more refreshments of intoxication. For the record...
Not much progress last night, but this looked weird. Bottom is the data line of the processor, middle is the data line going into the buffer, and the top is the CS* for one of the banks of EPROMs. None of the other CS* have than RC hump. I wish it gave me insight, but I this is only one one...
I put these on a few of my cabinets. They have an adjustable leg that you can screw down to lift the cabinet up off the wheels. If you have carpet, you might need to remove the locking nut to be able to screw the legs up high enough to clear the carpet if the wheel sinks low in the padding...
Ok, I see where A7 is wrong? A4? Or do I not know how the video works? I thought in the background, RAM was shifted out serially to the display. If A4 was stuck low, when the address tries to advance from 0x1F to 0x20, it would effectively roll back to 0x00 and count up until it hit 0x1F...
After @HudsonArcade pointed out my assumptions on how the memory is laid out was incorrect, I'm not so sure that the chip selects are the original problem. You should still continue to verify they are working properly. If they are, I would suggest circling back and look at the address lines...
I realized last night that I might be thinking about this entirely backwards. I noticed that the transients on the data lines stop very periodically. Below, the green is a data line and the red is AS (Address Strobe). AS dosen't show any correlation with the stops in the transient, so I kept...
Well, I pulled the 10 uF cap and checked the value/ESR. Seemed ok, but I swapped it with the other 68000 cap and no change.
It was a long shot, but I thought maybe a cold solder joint on a 68000 ground or something would cause transients, but I removed and resoldered all the solder joints of...