Commodore PLUS/4 & C16 PLA

  Inputs
I0    F7         X X - X 1 1 1 X 1
I1    phi 0      1 1 - X 1 1 1 X 1
I2    A15        1 1 - 1 1 1 1 X X
I3    A4         0 0 - X 1 1 1 X X
I4    A5         0 1 - X 1 0 0 X X
I5    A6         0 0 - X 0 1 0 X X
I6    A7         0 0 - X 0 1 0 X X
I7    A12        1 1 - 1 1 1 1 X X
I8    MUX        X X - X X X X 1 X
I9    A14        1 1 - 1 1 1 1 X X
I10   A8         1 1 - 0 1 1 1 X X
I11   A9         0 0 - 0 0 0 0 X X
I12   A13        1 1 - 1 1 1 1 X X
I13   A11        1 1 - 1 1 1 1 X X
I14   A10        1 1 - 1 1 1 1 X X
I15  -RAS        X 0 - X 0 0 0 X 0

  Outputs
F0   -?          X 0 1 X X X X X X
F1    phi 2      X X 0 X 1 1 1 X 1
F2   -USER       X X 1 X X X 0 X X
F3   -6551       0 X 1 X X X X X X
F4   ^ADDR CLK   X X 1 X X 0 X X X
F5   -KEYPORT    X X 1 X 0 X X X X
F6    KERNAL     X X 0 1 X X X X X
F7    I0         X X 0 X 1 1 1 1 1

  Legend
     0  low
     1  high
     X  input ignored; output unchanged
     -  indicates the default condition.

NOTE: Pin F0 is not connected to anything but is programmed.
      It's use is unknown.
NOTE: Pins I0 and F7 are connected together, apparently to
      provide a timing delay.


Commodore PLUS/4 & C16 MEMORY

           ------ CPU & Screen Read ------  - Character Set --
             Write    Read RAM   Read ROM   Read RAM  Read ROM
0000-7FFF     RAM        RAM        RAM        RAM
8000-BFFF     RAM        RAM      LO ROM       RAM     LO ROM
C000-FBFF     RAM        RAM      HI ROM       RAM     HI ROM
FC00-FCFF     RAM        RAM      KERNAL       RAM     KERNAL
FD00-FD0F   (6551)     (6551)     (6551)
FD10-FD1F  CAS(USER)  CAS(USER)  CAS(USER)
FD20-FD2F      ?          ?          ?
FD30-FD3F  KEYBOARD   KEYBOARD   KEYBOARD
FD40-FDCF
FDD0-FDDF  ROM LATCH
FDE0-FEFF
FF00-FF1F     TED        TED        TED        TED       TED
FF20-FF3D     RAM        RAM      HI ROM       RAM     HI ROM
FF3E       ROM SELECT             HI ROM               HI ROM
FF3F       RAM SELECT             HI ROM               HI ROM
FF40-FFFF     RAM        RAM      HI ROM       RAM
  ( ) NOT AVAILABLE ON THE C16

NOTE: FD20-FD2F is accessed by the kernal power-up routines, but
nothing inside the PLUS/4 or C16 is at this address.


LO ROM and HI ROM are determined by writing
to the appropriate ROM LATCH address.

ROM LATCH   LO ROM              HI ROM

FDD0        BASIC               KERNAL
FDD1        (FUNCTION LO)       KERNAL
FDD2        CARTRIDGE 1 LO      KERNAL
FDD3        CARTRIDGE 2 LO      KERNAL
FDD4        BASIC               (FUNCTION HI)
FDD5        (FUNCTION LO)       (FUNCTION HI)
FDD6        CARTRIDGE 1 LO      (FUNCTION HI)
FDD7        CARTRIDGE 2 LO      (FUNCTION HI)
FDD8        BASIC               CARTRIDGE 1 HI
FDD9        (FUNCTION LO)       CARTRIDGE 1 HI
FDDA        CARTRIDGE 1 LO      CARTRIDGE 1 HI
FDDB        CARTRIDGE 2 LO      CARTRIDGE 1 HI
FDDC        BASIC               CARTRIDGE 2 HI
FDDD        (FUNCTION LO)       CARTRIDGE 2 HI
FDDE        CARTRIDGE 1 LO      CARTRIDGE 2 HI
FDDF        CARTRIDGE 2 LO      CARTRIDGE 2 HI
  ( ) NOT AVAILABLE ON THE C16