Rom Pack Access - Casio SK 8A Service Manual & Parts List

11. ROM PACK ACCESS
Assigning ROM pack by being LOW of signal CE2, CPU reads data from the ROM directly and
generates programmed melody and accompaniment signals.
Since the data bus D4 ~ D7 carries data and address, signal OP determines either the bus carries
data or address.
Signal Cl and C2 are clock pulse for data transfer.
Cl
C2
OP
D4 ~ D7
HIGH
Data
LOW
Address
nnni innru innnnru it
-2.5/is
Innr
-~|—h10^s