Den Mon, 28 May 2018 14:00:44 +0300 skrev Marko Mäkelä <msmakela@gmail.com>: > On Thu, May 24, 2018 at 01:24:18AM -0500, Jim Brain wrote: > >I think it's going to be tough to pull the Z80. Bil Herd notes in > >his stories that the C128 bootup relies on the Z80 pulling startup > >vectors from low memory to handle carts like Magic Voice that play > >with the control signals when 6502 vectors are pulled. > > Yes, the C128 boots up with the Z80. I disassembled that ROM enough > so that I was able to remove the check whether -EXROM or -GAME are > pulled down during startup, because I did not want the computer to > enter C64 mode only because some C64 cartridge was plugged in. Maybe they made the C128 to start in C64 mode if EXROM/GAME are low to not upset cartridge vendors as starting it in C128 mode would make pirate copying the contents of simple cartridges trivial. Btw isn't there a risk of bus clashes and crashes if a more advanced C64 cartridge (like any freezer) is inserted while the computer is in C128 mode? Does the C128 react to GAME/EXROM at all when in C128 mode, except being able to read them through a register? > The Z80 also checks if the C= key is pressed. The C= key check is > duplicated by the C128 KERNAL ROM. Interesting. One hand doesen't know what the other is doing? :) -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies.Received on 2018-06-06 21:02:11
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