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Jammer
Registered: Nov 2002
Posts: 1336 |
C64/C128 combo program compilation
Question might turn out plainly stupid so bear with me but I'm total noob on C128.
Can C64 program be compiled to run both on C64 and C128 in its native 128k mode if it has appropriate branches in code? Or it's always two separate tailored builds?
I've already learnt that C128 program startup is either $1C01 or $4001 but if C128 startup was embedded at the right spot, would it still launch? |
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tlr
Registered: Sep 2003
Posts: 1791 |
For the record, it's quite common to have load addr independent sys starts on the vic20 because the basic start may be at different addresses depending on memory expansion.
Simply include $2c/PEEK(44) in your address calculations.
Using this method you can make a binary that starts from basic on most/all commodore 8-bits. |
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JackAsser
Registered: Jun 2002
Posts: 2014 |
Quote: for that, just always do the d030 switching in the border. no need to detect anything :) (and then it will automagically also work with other turbos that use that bit)
As GP said. Just flip the bit in the border regardless if it's a C128 or C64. It doesn't matter for the C64, and a C128 user will get the boost. No problems. |
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MagerValp
Registered: Dec 2001
Posts: 1078 |
Quoting tlrSimply include $2c/PEEK(44) in your address calculations.
Using this method you can make a binary that starts from basic on most/all commodore 8-bits.
In C128 mode basic start is at $2d/$2e instead, so it requires a little more logic. Certainly still doable, but I don't think I've seen a ready to use basic stub for both C64 and C128? |
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Jammer
Registered: Nov 2002
Posts: 1336 |
If I can switch to 2MHz in C64 mode as well, that's perfectly what I need. Thanks! |
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oziphantom
Registered: Oct 2014
Posts: 490 |
just doing 2Mhz in the borders, leaves a lot of performance on the table though. If you are doing a native version then you can make full use of the 128.
But if you want to do it in a single load that might be a problem, you would probably need to load "128 patches" after the main binary to replace the 64 versions with the faster 128 versions. |
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Jammer
Registered: Nov 2002
Posts: 1336 |
Should Vice C128 switch back to 128 mode and crash the machine if I only attach/load file in GO64 mode? |
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oziphantom
Registered: Oct 2014
Posts: 490 |
if you autostart it, it will then reset the machine and hence boot in 128 mode. You need to attach the d64 and then load in C64 mode. |
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tlr
Registered: Sep 2003
Posts: 1791 |
Quote: Quoting tlrSimply include $2c/PEEK(44) in your address calculations.
Using this method you can make a binary that starts from basic on most/all commodore 8-bits.
In C128 mode basic start is at $2d/$2e instead, so it requires a little more logic. Certainly still doable, but I don't think I've seen a ready to use basic stub for both C64 and C128?
Aha, didn't know that. Seems it's different on the PET as well now that I look it up. It's apparently only the kernal that is somewhat compatible. |
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Krill
Registered: Apr 2002
Posts: 2982 |
Quoting JammerIf I can switch to 2MHz in C64 mode as well, that's perfectly what I need. Thanks! Great! :)
Your original "C128 in its native 128k mode" implied actual native C-128 mode usage, such as using all 128 KB of RAM, relocateable zeropage and stack, double-buffered $D800 colour RAM and whatnot.
But if you only need 2 MHz, awesome. =)
Take care to have smoother but not faster gameplay with various turbo speeds of up to 48 MHz (update state in VBL or using the timers).
Wolfenstein engine thingy in One-Der is a good example for that, plays silky-smooth on U64@48MHz. |
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Jammer
Registered: Nov 2002
Posts: 1336 |
Quoting oziphantomif you autostart it, it will then reset the machine and hence boot in 128 mode. You need to attach the d64 and then load in C64 mode.
There's 'Autostart' option and 'Attach/Load' which, I guess, shouldn't reset the machine, only fill memory with file data. It works properly for x64sc at least but I suppose it's that bootblock mechanism, inherent to C128? |
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