• Please review our updated Terms and Rules here

Cbm 2001 Pet strange boot

I burned your program on 2532 eprom but unfortunately i have always same situation and also same scrambled chars screen :(
 
Desperado said:
I burned your program on 2532 eprom but unfortunately i have always same situation and also same scrambled chars screen :(
Click to expand...

You will still have scrambled characters on the screen! There is no code in the EPROM to affect the screen other than the FIRST character position.

Having a scrambled screen does not mean that the new firmware isn't working!

Have you tested the outputs of UD2 and (if so) what are the results please.

Dave
 
daver2 said:
Sorry I misread your last post.

Can you check the address lines of the CPU and see what they are doing please?

Dave
Click to expand...
Ok i have this waveform on every Cpu pins (26 to 33) except for pin 30 (picture number 2)
 

Attachments

  • 1.png
    1.png
    1 MB · Views: 2
  • 2.png
    2.png
    934.5 KB · Views: 2
daver2 said:
That's interesting, but I did ask for the CPU address lines not the data lines.

Dave
Click to expand...
I have waveform only on pin9 and something on pin 17 :(
 

Attachments

  • pin9.png
    pin9.png
    1,000.2 KB · Views: 2
  • pin17.png
    pin17.png
    1.1 MB · Views: 2
Desperado said:
with scope i can see only horizontal line with 0,2 V level :( I am desperate...6502 faulty, correct??
Click to expand...
Unlikely! That is a guess again isn't it.

Just to put you out of your misery (!) do you want to swap the 6502 CPU for another one and check that you have the same issue?

We can then get on and find the elusive fault without having to address the faulty 6502 CPU again.

You never know - it may be faulty :)...

I suspect the CPU is only doing what it has been told (erroneously) to do!

The scope timebase or trigger level is not set correctly for pin 17 from post #1,513. The presence of two horizontal lines on the scope (with a single channel selected) indicates that for one sweep of the electron beam the signal was LOW and for another it was HIGH. You need to slow down the timebase (a longer time per division) or adjust the trigger level to get the trace stable.

Can you 'dump' the EPROM you programmed for UD9 and post the dump please so I can double check it?

Dave
 
If you can program an EPROM from a PC using an EPROM programmer there will be a way of reading the EPROM using your EPROM programmer and uploading the image file back to the PC.

Read the manual for the EPROM programmer?

Dave
 
It must be said, I have only ever had two failed CPU's and both of them have been 6502's :)

but in both cases, they did nothing (ie no waveforms at all). In the Apple ][, all the address lines sat at 3V and in the 8032SK I got nothing out of any line.
 
You must log in or register to reply here.
Back
Top