Cbm 2001 Pet strange boot

[daver2]

Just use your EPROM programmer first.

Load a blank 2532 into the programmer, read the EPROM into the programmer’s memory, edit the memory image (at the correct addresses) to change the FF bytes to my program, double check your work and burn the EPROM.

Dave

 

[Desperado]

Just use your EPROM programmer first.

Load a blank 2532 into the programmer, read the EPROM into the programmer’s memory, edit the memory image (at the correct addresses) to change the FF bytes to my program, double check your work and burn the EPROM.

Dave

unfortunately i can t see FFED offset in this sotware

 

[daver2]

You won't!

The EPROM is 4K - so the offsets are from 0000 to 0FFF.

The Additional 'F' is put in by the address decoding logic in the PET and the EPROM itself knows not anything about it!

Scroll the window you have to address 0FED (it should be at the end of the scrollable window) and enter the bytes of my test program. They should go up to (and include) address 0FFF.

Dave

 

[Desperado]

Scroll the window you have to address 0FED (it should be at the end of the scrollable window)

i haven't 0FED

 

[Desperado]

I have this:

 

[Nivag Swerdna]

Can I recommend using the abracadabra.bin (contained in the .zip) from Post # 519 ? Earlier Post #519

This is a 4K Image that is to be burnt into a ROM to replace the Kernel.

It writes to and reads from video memory which is what I think you are trying to currently achieve?

 

[Desperado]

Hi Nivag, thanks but i don't know if this Abracadabra.bin can be fine like Dave s' program.... Dave??

 

[daver2]

I have this:

This is hard going I am afraid...

Look at the left hand side - the numbers are 0FE0 and 0FF0.

Note that they are 10 (hex) apart = 16 (dec) bytes.

Then note at the top of the page that the numbers go from 0 at the left to F at the right (10 hex bytes = 16 decimal bytes).

So, this is like a spreadsheet with the left hand cell (at 0FE0) being address 0FE0. The next cell along being address 0FE1 and so on to the end of that line (where the address is 0FEF).

You then start on the next line with 0FF0 and so on along the line horizontally to address 0FFF on the bottom line right-hand side.

Therefore, the address 0FED is on the line starting with address 0FE0 and where it intersects with the column identified as 'D'.

Dave

 

[daver2]

Why so sad?

Dave

 

[Desperado]

Why so sad?

Dave

It's a very difficult for me this
Can i use Nivag s' abracadabra.zip ????

 

[Desperado]

This is hard going I am afraid...

Look at the left hand side - the numbers are 0FE0 and 0FF0.

Note that they are 10 (hex) apart = 16 (dec) bytes.

Then note at the top of the page that the numbers go from 0 at the left to F at the right (10 hex bytes = 16 decimal bytes).

So, this is like a spreadsheet with the left hand cell (at 0FE0) being address 0FE0. The next cell along being address 0FE1 and so on to the end of that line (where the address is 0FEF).

You then start on the next line with 0FF0 and so on along the line horizontally to address 0FFF on the bottom line right-hand side.

Therefore, the address 0FED is on the line starting with address 0FE0 and where it intersects with the column identified as 'D'.

Dave

ok...maybe i understand...i try

 

[Malc]

As Dave said, Scroll down to the second line from the bottom of the window, See if this helps.

000FE0 00 00 00 00 00 00 00 00 00 00 00 00 00 A9 00 8D 000FF0 00 80 A9 FF 8D 00 80 4C ED FF ED FF ED FF ED FF

 

[daver2]

Yes.

I think (to be honest) that you need to learn a bunch of skills before succeeding in repairing the more difficult faults.

Let's give this thread a little more time to run and see where we get to.

After that, you really need to source some good books on using your oscilloscope and basic digital logic. There will be some good books on these subjects in Italian in a decent university bookshop or similar.

You also need to get to know your EPROM programmer better etc. You need to learn how to download both HEX and BIN files, how to manually edit and enter simple test programs and how to download and save EPROM images to files. These are all basic skills (much like soldering and desoldering) that you need to master.

You won't be able to assemble your own test programs (yet) but a good book on 6502 PET machine code - and the use of TIM (the PETs debug monitor) will help.

Even Hugo (who is an absolute whiz with digital logic) is learning PET machine code...

Dave

 

[daver2]

Yep, Malc's got it!

Dave

 

[Desperado]

Yes! Now i understand..thanks to Dave and Malc!
It's like a big easy warship game
Thanks so much, now i burned my eprom!
Il' try this eprom tomorrow with clear mind, for today my brain it is cooked enough eheh

Good night and thanks again....I want to be the biggest and most desperate pet fixer

 

[daver2]

Well done !!!

Dave

 

[Desperado]

Well done !!!

Dave

Just for clarity....what should i expect on screen?
And what with scope?
Thanks!

 

[daver2]

>>> Just for clarity....what should i expect on screen?

The screen will have the usual random characters - so don't get desperate - this is the expected response (partly)!

Look at the very first character of the screen (the top left-hand corner) it should either be an '@' character, the 'checkerboard' character or (more likely) a combination of the two. You won't be able to see each separate character as they will be changing so fast.

Check that you have a SYNC signal on the CPU.

The thing to look for is on the output pins of UD2 again with the oscilloscope. You are looking for output signals with pulses on them. Post which ones are changing.

Dave

 

[Desperado]

>>> Just for clarity....what should i expect on screen?

The screen will have the usual random characters - so don't get desperate - this is the expected response (partly)!

Look at the very first character of the screen (the top left-hand corner) it should either be an '@' character, the 'checkerboard' character or (more likely) a combination of the two. You won't be able to see each separate character as they will be changing so fast.

Check that you have a SYNC signal on the CPU.

The thing to look for is on the output pins of UD2 again with the oscilloscope. You are looking for output signals with pulses on them. Post which ones are changing.

Dave

Ok....then it doesn't work
I see only this screen and nothing change

 

[daver2]

Have you checked with the scope yet?

Dave