On Wed, Jul 07, 2010 at 10:46:40PM -0700, Brenda wrote: >> Some updates about the C128 (in case someone's interested). > >maybe its too obvious but have you tried a different monitor and >monitor cable? How would that fix garbage characters on the screen? My bet is on the low RAM. The stack lives in $0100-$01ff, and if an RTS instruction reads a garbage return address from the stack, it would freeze the system. Does the computer enter C64 mode when you hold down the Commodore key or tie the EXROM line to ground while powering it up? I seem to remember that the C128 KERNAL initializes the screen colors ($d020/$d021) earlier than the C64 KERNAL. If you don't get the blue screen in C64 mode but do get the green/gray in C128 mode, then that could narrow down the search. In any case, the Z80 processor should be running fine, because it is the Z80 that switches the control to the 8502. There are two checks for entering the C64 mode, both in the Z80 BIOS and in the C128 KERNAL. I know, because I patched the Z80 BIOS in my system in some way, IIRC something that was related to controlling my 1-megabyte internal memory expansion <http://www.iki.fi/~msmakela/8bit/memory/>. Marko Message was sent through the cbm-hackers mailing listReceived on 2010-07-08 07:00:11
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