Floppies_only
Veteran Member
Persons old enough may remember a particularly bad TV show called "Voyage To The Bottom Of The Sea". It was a science fiction show that followed the crew of a futuristic submarine (that could go from Hawaii to California in just hours, wow!) and the way production designers represented computers back then was with a large panel of flashing lights. The lights are kind of like the L.E.D.s on the IMSAI in that they are meant to help diagnose software problems.
Anyway, I acquired the September, 1979 issue of Kilobaud because it had an article on the Heathkit ET-3400. But it also had an article on how to build a board with status lights that attaches to the KIM-1 personal computer (but I'm sure it can be adapted to other computers and microprocessor trainers, like the '3400). The article explains that displaying the status of the address pointer and registers involves modifying the monitor program to load these values into reserved bytes of memory as it oversees running the program under test. The circuit diagram and block diagram are designed to display the value of the byte being pointed to by the address pointer, but also shown is a way to display the values of other bytes of memory (so you could see the registers and address pointer values).
Of course, at the ET-3400's 500 KHz clock rate, these would just be a blur unless the program locked up. Enter Chromedome45's reference to a way to add an EPROM to the '3400. It could be programmed with the existing monitor modified with a delay loop so that the lights would flash slowly and you could watch the program being executed. I think it would be fun to watch the lights flash just like the TV computers from the sixties.
Lessee, I guess that the person modifying the monitor program would have to ensure that the address pointer, address byte, and register values were not modified by the delay loop, but that would be simple enough. It should be possible to set the amount of delay desired by the user.
The link to the EPROM addition to the ET-3400 is in message #4 of the "Heathkit ETA-3400 with unusual switch" thread. If anybody wants a Xerox copy of the KIM-1 status board article from Kilobaud, send me a PM.
Sean
Anyway, I acquired the September, 1979 issue of Kilobaud because it had an article on the Heathkit ET-3400. But it also had an article on how to build a board with status lights that attaches to the KIM-1 personal computer (but I'm sure it can be adapted to other computers and microprocessor trainers, like the '3400). The article explains that displaying the status of the address pointer and registers involves modifying the monitor program to load these values into reserved bytes of memory as it oversees running the program under test. The circuit diagram and block diagram are designed to display the value of the byte being pointed to by the address pointer, but also shown is a way to display the values of other bytes of memory (so you could see the registers and address pointer values).
Of course, at the ET-3400's 500 KHz clock rate, these would just be a blur unless the program locked up. Enter Chromedome45's reference to a way to add an EPROM to the '3400. It could be programmed with the existing monitor modified with a delay loop so that the lights would flash slowly and you could watch the program being executed. I think it would be fun to watch the lights flash just like the TV computers from the sixties.
Lessee, I guess that the person modifying the monitor program would have to ensure that the address pointer, address byte, and register values were not modified by the delay loop, but that would be simple enough. It should be possible to set the amount of delay desired by the user.
The link to the EPROM addition to the ET-3400 is in message #4 of the "Heathkit ETA-3400 with unusual switch" thread. If anybody wants a Xerox copy of the KIM-1 status board article from Kilobaud, send me a PM.
Sean
Last edited: