adko
Member
Thank you Nivag, I already have the eeprom reader at home
I'm going to look for that adapter now
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PET 2001 with Rabbit ROM
- Thread starter adko
- Start date
I'm going to look for that adapter now
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adko
Member
Hi Dave, what a lot and difficult workI have entered and disassembled a bit more...
I have imported the PET BASIC 2 symbol table into the disassembler so it can label things automagically for me without me staring at HEX numbers all night. It is even making sense. I suspect that address $A000 is NOT the entry point. It seems as though this is the 'wedge' entry point - meaning that it will all go **** up if we invoke that address with a SYS command!
I'll do a couple more pages tomorrow and another disassembly.
I see where some of the commands are manipulating cassette ports #1 and #2...
Dave
I could never do this myself, I don't have enough knowledge for that
Thank you for all your energy and time
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adko
Member
daver2
10k Member
Yep, we found that back in post #3
...I suspect the modification to HIMEM is purely for the cassette version. It will load into a memory location that exists on all PETs and will relocate itself to the top of memory and then modify the BASIC pointers to hide itself. The ROM version shouldn't need to do that.
>>> I could never do this myself, I don't have enough knowledge for that.
I am just transcribing the HEX bytes from your photographs at the moment. No real skill involved in that! It is quite therapeutic actually to "be one with the hex"...
>>> Thank you for all your energy and time
I think this will be of general use to the PET community - so well worth the effort...
It will take me a few days to enter - do a bit at a time. If you do too much in one go, I will start to make daft mistakes...
Dave
daver2
10k Member
Please find today's efforts in the linked file...
It's nice when text messages start to appear!
The file contains a HEXDUMP of the complete EPROM image (including the bits I haven't done yet) followed by the disassembly.
Of course, now I am finding embedded tables and text, the disassembler doesn't know any different - so it is trying to make sense of the text messages and data (and failing dismally)! I can tell the disassembler where the data areas are, and what they are (data bytes, words, text etc.) and it will decode them accordingly. But that's for later.
I see there is the message "RABBIT AVAILABLE"contained within the ROM, so the challenge should be to see if we can get the PET to produce this message!
I also see that the message "SYNTAX ERROR!" is here as well (but it is different to the message you appear to be getting when you enter the command "SYS 40960").
Dave
It's nice when text messages start to appear!
The file contains a HEXDUMP of the complete EPROM image (including the bits I haven't done yet) followed by the disassembly.
Of course, now I am finding embedded tables and text, the disassembler doesn't know any different - so it is trying to make sense of the text messages and data (and failing dismally)! I can tell the disassembler where the data areas are, and what they are (data bytes, words, text etc.) and it will decode them accordingly. But that's for later.
I see there is the message "RABBIT AVAILABLE"contained within the ROM, so the challenge should be to see if we can get the PET to produce this message!
I also see that the message "SYNTAX ERROR!" is here as well (but it is different to the message you appear to be getting when you enter the command "SYS 40960").
Dave
daver2
10k Member
OK - so I have been doing a little playing with XPET and loading the partially complete Rabbit ROM into the emulation.
The command "SYS 40960" produces the error "?syntax error".
However, the command "SYS 40963" just returns you back to the BASIC "ready" prompt again with no error. I think this conclusively demonstrates that 40960 is NOT the starting entry point of the ROM, and that the "?syntax error" message is produced as a result of incorrectly executing the ROM code at the wrong entry point.
We now just have to find the correct entry point...
More disassembling...
Dave
The command "SYS 40960" produces the error "?syntax error".
However, the command "SYS 40963" just returns you back to the BASIC "ready" prompt again with no error. I think this conclusively demonstrates that 40960 is NOT the starting entry point of the ROM, and that the "?syntax error" message is produced as a result of incorrectly executing the ROM code at the wrong entry point.
We now just have to find the correct entry point...
More disassembling...
Dave
daver2
10k Member
I am halfway there now.
I am somewhat tired now, so I am calling it a day/night!
Dave
I am somewhat tired now, so I am calling it a day/night!
Dave
daver2
10k Member
Too easy. Give me a more difficult one...
try "sys 42014"...
I have found an 'extra' command by just typing a '*' on its own. This gets you into the machine code monitor (TIM). To exit from TIM back to BASIC type an 'x'. I did actually read this somewhere though (in one of the reviews I found). All the other commands seem to map onto those detailed in the cassette version.
I will continue to enter the hex dumps though so that others can have a binary copy of it to burn into a ROM if they wish. I see there is reference to a version for BASIC 4 as well.
Enjoy.
Dave
try "sys 42014"
...I have found an 'extra' command by just typing a '*' on its own. This gets you into the machine code monitor (TIM). To exit from TIM back to BASIC type an 'x'. I did actually read this somewhere though (in one of the reviews I found). All the other commands seem to map onto those detailed in the cassette version.
I will continue to enter the hex dumps though so that others can have a binary copy of it to burn into a ROM if they wish. I see there is reference to a version for BASIC 4 as well.
Enjoy.
Dave
adko
Member
Hi Dave, you did it 
With sys 42014 the rom of Rabbit starts
And can I use the commands *L etc to load the cassette files faster
Now everything really works on my PET as it should
Many thanks for your enormous patience and knowledge to solve this
So I think the code on the ROM can also be used by others if they write this code to a ROM
I'm glad that this useful extension for PET is working
Thank you very much
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With sys 42014 the rom of Rabbit starts
And can I use the commands *L etc to load the cassette files faster
Now everything really works on my PET as it should
Many thanks for your enormous patience and knowledge to solve this
So I think the code on the ROM can also be used by others if they write this code to a ROM
I'm glad that this useful extension for PET is working
Thank you very much
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adko
Member
Hi Nivag, it worked
Dave has found that with sys 42014 I can start and use the Rabbit rom
I also want to thank you for all your help and energy
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daver2
10k Member
>>> Thank you very much.
Absolutely no problem at all. Glad to be of help - and we hope you will continue to enjoy VCFED. You never know when you may need our PET services again!
I will continue to enter the hex code from your photographs (but probably as a lower priority task) and post it somewhere for others to download and use should they wish.
However (to ensure that I have transcribed things correctly) I will post a little BASIC program in a few days time for you to run so that I can check my work is accurate.
EDIT: Can you correct the SYS call in the body of the text of post #70 to 42014 (just to avoid confusion in the future)...
Enjoy...
Dave
Absolutely no problem at all. Glad to be of help - and we hope you will continue to enjoy VCFED. You never know when you may need our PET services again!
I will continue to enter the hex code from your photographs (but probably as a lower priority task) and post it somewhere for others to download and use should they wish.
However (to ensure that I have transcribed things correctly) I will post a little BASIC program in a few days time for you to run so that I can check my work is accurate.
EDIT: Can you correct the SYS call in the body of the text of post #70 to 42014 (just to avoid confusion in the future)...
Enjoy...
Dave
Gary C
Veteran Member
What an amazing bit of work. Well done you two.
dave_m
Veteran Member
Fantastic 'PET' Detective work!
Gary C
Veteran Member
Oh very droll
daver2
10k Member
Perhaps I’ll change my avatar to Ace !
Although the Google searches for “rabbit” turned up some ‘interesting’ websites!
Dave
!Although the Google searches for “rabbit” turned up some ‘interesting’ websites!
Dave
Gary C
Veteran Member
Don't try that at work !
Eudimorphodon
Veteran Member
Hah! I've got a particularly weird story about what I stumbled across when I was dumb enough to google the name of a Pokemon my kid was obsessed with that day. Suffice it to say there's some strange... and apparently very lonely, people out there. And they buy things from Alibaba.com. Things that very game-faced factory workers (who I assume are being held at gunpoint) are forced to pose with.
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VERAULT
Veteran Member
We now live in a world which both shuns and allows weird behavior.. dont you love hipocracy?
Congrats on figuring out the ROM startup location.
Has it been backed up to the internet for other folks?
Congrats on figuring out the ROM startup location.
Has it been backed up to the internet for other folks?
daver2
10k Member
>>> Congrats on figuring out the ROM startup location.
Cheers.
>>> Has it been backed up to the internet for other folks?
Not yet - but it will be. I am currently entering the hex dump photographs into a file... It was the simplest way at the time!
Dave
Cheers.
>>> Has it been backed up to the internet for other folks?
Not yet - but it will be. I am currently entering the hex dump photographs into a file... It was the simplest way at the time!
Dave
VERAULT
Veteran Member
Hey if that method works for you, you wont hear me criticize it. My wife still gives me hell about buying printer paper when we receive enough junk mail to fuel home heating bills.
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