john@wsl.UUCP (John Allen on wsl) (11/10/89)
A friend has a VIC-20 and an 8K memory expansion cartridge. The memory cartridge does not appear to be working. What I want to know is are there any switches/jumpers to be set on the system board to make this cartridge work, or should it work by just plugging it in. Thanks for any info that can be supplied. -- "Don't quote me on any issue whatsoever."
jgreco@csd4.csd.uwm.edu (Joe Greco) (11/11/89)
In comp.sys.cbm article <276@wsl.UUCP>, john@wsl.UUCP (John Allen on wsl) wrote: >A friend has a VIC-20 and an 8K memory expansion cartridge. The memory >cartridge does not appear to be working. > >What I want to know is are there any switches/jumpers to be set on the >system board to make this cartridge work, or should it work by just >plugging it in. Depends. A Commodore 8K expander? As I recall, that unit could be configured to work in any of the four 8K blocks that you could put RAM into. There should either be some DIP switches on the case, or perhaps inside the case. The VIC's memory layout went something like this (very loosely): $0000-$03FF Internal RAM $0400-$0FFF Open for 3K External Expansion $1000-$1FFF 4K Internal RAM $2000-$3FFF 8K External RAM (RAM1) $4000-$5FFF 8K External RAM (RAM2) $6000-$7FFF 8K External RAM (RAM3) $8000-$8FFF I/O Block $9000-$9FFF Character Generator ROM $A000-$BFFF 8K External RAM (RAM5) $C000-$FFFF BASIC and KERNAL ROMs. Your 8K expander could be mapped into RAM1, RAM2, RAM3, or RAM5. For BASIC to recognize it, you must start by filling RAM1 (or the 3K slot, but you need a 3K expander for that) and adding upwards. You may add up to 24K total (RAM1-3). RAM5 is mostly used for ML applications and cartridges. It's quite likely that your expander is set for RAM2, RAM3, or RAM5. If it is, it is working - but BASIC cannot see it because BASIC needs continuous memory. Check the switches. Further problems? Send me E-mail. I never had one of the CBM 8K expanders, but I am familiar with the VIC. -- jgreco@csd4.csd.uwm.edu Joe Greco at FidoNet 1:154/200 USnail: 9905 W Montana Ave PunterNet Node 30 or 31 West Allis, WI 53227-3329 "These aren't anybody's opinions." Voice: 414/321-6184 Data: 414/321-9287 (Happy Hacker's BBS)