COmmodore 64 vs 128

[Fröhn]

Are 128's fully compatible with 64 cartridges and programs? If I remember correctly, there was a switch on the 128 to run in 64 mode. Is this a true 64 mode?

Yes, compability is nearly 100%.

 

FOr instance, if I was learning assembly for the 64 would it apply to the 128?

Imagine the C128 as an extended C64.

[+SpiceWare]

Andrew Braybrook wrote some of his games to exploit the 2MHz CPU speed over the C64's 1MHz if you were playing his games on a 128 in 64 mode. Would add extra enemies and small features.

How is that possible? I was under the impression that in order to switch to 2MHz mode, the VIC-II chip had to be disabled, which would make C64 mode useless.

I wrote a short raster interrupt program that would turn on 2 MHz when the bottom border started and turn back to 1 MHz when the top border ended. It wasn't compatible with everything, but I found it useful for making BASIC programs run about 25% faster.

[+SpiceWare]

I was always disappointed that the VDC chip was so limited in it's capabilities compared to the VIC-II... I was looking forward to pulling off some nifty high-res graphics, but the chips abilities really only work well for displaying text

The VDC could be used for games

 

 

I started work on a version of asteroids and used the VDC's blitter to rotate the asteroids. I'd also gotten the ship to fly around but hadn't yet added the shots when I bought an Amiga and lost interest in finishing the game.