APPENDIX SIXTEEN



the access to the second bank is enabled. Here are the possible bit
contigurations (M stands for main bank, E for extended or secondary
bank):

Compatibility mode (only main bank enabled)
Bit 5   Bit 4   Bit 3   Bit 2   CPU accesses:   ANTIC accesses:
VBE     CPE     Bank selection
1       1       doesn't matter  M $4000-$7FFF   M $4000-$7FFF

CPU extended RAM mode
Bit 5   Bit 4   Bit 3   Bit 2   CPU accesses:   ANTIC accesses:
VBE     CPE     Bank selection
1       0       0       0       E $0000-$3FFF   M $4000-$7FFF
1       0       0       1       E $4000-$7FFF   M $4000-$7FFF
1       0       1       0       E $8000-$BFFF   M $4000-$7FFF
1       0       1       1       E $C000-$FFFF   M $4000-$7FFF

Video (ANTIC) extended RAM mode
Bit 5   Bit 4   Bit 3   Bit 2   CPU accesses:   ANTIC accesses:
VBE     CPE     Bank selection
0       1       0       0       M $4000-$7FFF   E $0000-$3FFF
0       1       0       1       M $4000-$7FFF   E $4000-$7FFF
0       1       1       0       M $4000-$7FFF   B $8000-$BFFF
0       1       1       1       M $4000-$7FFF   E $C000-$FFFF

General extended RAM Mode
Bit 5   Bit 4   Bit 3   Bit 2   CPU accesses:   ANTIC accesses:
VBE     CPE     Bank selection
0       0       0       0       E $0000-$3FFF   E $0000-$3FFF
0       0       0       1       E $4000-$7FFF   E $4000-$7FFF
0       0       1       0       E $8000-$BFFF   E $8000-$BFFF
0       0       1       1       E $C000-$FFFF   E $C000-$FFFF

To select which mode and bank you want to access in
BASIC, use

POKE 54017, 193 + (MODE * 16) + (BANK * 4)

For MODE and BANK, chose the number below which represents the
type and area at address:

    MODE                BANK
No. 6502   ANTIC        No.    Address
0   Extd   Extd         0      $0000-$3FFF
1   Main   Exd          1      $4000-$7FFF
2   Extd   Main         2      $8000-$BFFF
3   Main   Main         3      $C000-$FFFF

Access to the extended memory is always through the bank
$4000-$7FFF, so no matter what the address of the extended bank,