I have tried also to use the wire wrap direction, and found that the wires acted like
antennas, with the bus speeds. This put out a lot of noise, and loaded down my CPU with a fanout rate.
Yeah, I thought that might be a possibility, but I am not experienced enough to know if it is an issue in my case or not. Just to be sure, I set up a test jig for the 8155 on a breadboard, and tried to write to it slowly using an Arduino board. That proved to be unsuccessful, and after several other attempts, I came to the conclusion that the chips were dead.
I ordered some new ones off of Ebay, and tried to write to those using the same test setup, however I was unsuccessful. At that point I began to doubt whether my test setup was correct, so I installed one of the new 8155s on robot.
Previously, when I still was using the refurbished chips, I had attempted to program the robot using the manual programmer. It turns out that I had wired it incorrectly, and the address/data bus lines were mixed up. Instead of attempting to fix the programmer, I tried to use the automatic programmer which I thought was working. However as is evident from my previous posts, those attempts proved to be futile.
Now that I had installed the new chip on the robot, I attempted to program the robot with the automatic programer, but that was ineffective. At this point I thought that the automatic programer might have a problem, so rather than try to debug its the hardware and code, I fixed the manual programmer and housed it in a tea tin. (Previously I had it in a cardboard box, but it looked really suspicious with wires hanging out, a red 7-segment display, and a bunch of red buttons, so I decided that I should make it a little less threatening.) I then used the manual programmer to program the robot to simply stand still, (if you remember, in its naturally unprogrammed state, the robot rolls backward,) and when I was finished, the robot did not move, indicating the the programming had been successful.
So it appeared that the new chips and the manual programmer worked, but that the automatic programmer did not. The next day I attempted to program the robot again with the manual programmer, but the programmer acted erratically. Since then I have tried to repair it, but have had little success.
Attached to this post are two pictures of the manual programmer. To operate the programmer, the programmer is first plugged into the back of the robot. Then the two toggle switches directly under the display are used to select which chip to write to. Next, the address to which the data is to be written is set up using the two red buttons on the right side of the programmer. Once the correct address is selected, the button on the top left of the programmer is pushed to latch the address. Then the two buttons on the right side are used again, except this time, to set up the data to write to the address that was previously latched. Once the data is set up, the bottom left button is pushed to write that data.