From: Daniel Kahlin (tlr_at_stacken.kth.se)
Date: 2005-11-03 19:16:12
On Thu, 3 Nov 2005, Baltissen, GJPAA (Ruud) wrote:
>> The one in the Data Becker book "64 intern" is great if you
>> can get it. Comments in German though. That's how I learnt
>> German by the way. :)
>
> I have various books myself, including the above. But I want one in
> electronic format to use as base for my own Kernal. I have a Kernal
> generated by my own disassembler but one without any comments. OK, I already
> started to fill in my own but being a lazy person..... :)
Ah. :)
Let me share some of my experience with kernal patches...
It might be easier to do it this way depending on what you need to
modify.
When I did the (still experimental) kernal patch for over5, I wrote it as
a patch right from the start. It is patched in 2 layers. First
I apply a patch to strip out all RS232 and tape code, and the I apply a
patch to insert the over5 code in parts of the freed areas. Both patches
are written using dasm as cross-assembler. I use the same source code for
both the standalone over5 programs, and the kernal patch versions.
There are two, nay three, points of making this as a patch:
1. Redistibution problems, you may or may not want to distribute
Commodores original rom.
2. Compatibility #1: there are versions of the kernal, various keyboard
mappings for example. Making a patch could make it work with all of
those.
3. Compatibility #2: Most software assume that as good as every routine
(even internal) is present at the same address.
If you don't need it to work with everything, it's no problem ignoring
thoses points ofcourse. :)
Also, even if you code it as a full kernal you can always make it a patch
later.
Regards
/Daniel
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