Posted By
DeadTED
on 2004-07-27
09:48:16
|  writing software to eprom
Hi all,
I have created a relay switching circuit for my +4 to control a model railway. I would like to program an eprom to sit an a +4 auto boot cartridge (like jack attack), so that when I switch the machine on the program comes on immediately.
Can anyone help me write a little test program and give me instructions on how to burn it to eprom. What language would I need to use? what type of eprom do I use e.g. 2764, 27128...
I already have an eprom burner.
Any help would be greatly appeciated.
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Posted By
Gaia
on 2004-07-28
11:21:13
| Re: writing software to eprom
I can't help with the EPROM's but the language you must use is definitely the MOS 6502 assembly. There's a four byte long magic word (CBM something) that must be at a certain position (check the BASIC ROM for the exact place) and your startup code must be placed at $8000 if I'm right for the kernal to interpret your cart as being valid... You could maybe dissect one such autostart cartridge along with a disassembly of the relevant parts of the plus/4 kernal.
Anyways, you're probably better off directing your HW-hack related questions to the CBM hackers mailing list at:
http://www.softwolves.pp.se/misc/arkiv/
There are a lot of friendly and competent people hanging out there.
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Posted By
Csabo
on 2004-07-28
19:36:32
| Re: writing software to eprom
The eprom should begin with this:
JMP $xxxx ; cold-start
JMP $xxxx ; warm-start
0
CBM
The reason why some eprom's don't autostart, is because at the end of the cold-start routine they jump back to basic. If you just write your program and not return: you have "autostart".
The 0 byte is an ID, the value could be anything. The CBM characters must be there so that the KERNAL recognizes the eprom.
TPSH knows a lot about this subject. He created several custom eproms for himself and other scene members.
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Posted By
DeadTED
on 2004-07-29
07:03:40
| Re: writing software to eprom
Thanks for the advice. I will continue with my enquiries. I have a book which covers this topic at extensively "Commodore 16 Exposed" from melbourne house, I just cannot understand the stuff, without someone walking me through a simple example.
Maybe I will scan the relevant chapters and post them. Maybe if someone else reads them they can understand them better than me.
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Posted By
DeadTED
on 2004-07-29
07:15:35
| Gaia I can not speak German (EOM)
.
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Posted By
Gaia
on 2004-07-29
11:21:30
| Re: writing software to eprom
That is a Swedish page anyway, but the mailing list is in English, of course.
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