My Apple II+ is not working right. Most times it will boot up and run
without a problem, and other times it will just freeze while working
and I need to do a shutdown and let it "cool off". Yesteday night, I
decided to open the case just after it froze and feel the temperature
of the chips: The processor was extremely hot!
I hooked up my scope to the 6502 chip and looked at the signals going
into and out of the processor. To get a good activity from the
processor I wrote a simple 6-line program to plot a dot at each hi-res
screen positition:
10 HGR2
20 FOR Y = 0 TO 191
30 FOR X = 0 TO 279
40 HCOLOR=INT(RND(1)*7)
50 HPLOT X,Y
60 NEXT X : NEXT Y : GOTO 20
While the processor was running I was getting nice signals from the
timing references and as the address and data busses were being
actionned. When it froze, all the signals from the processor were
gone. It was as if the processor had been physically removed. The
processor was very hot again.
I will be buying a new processor. Since the R65C02 (Rockwell) is a pin
for pin identical to the 6502 (but with extended code), can I use it
instead?