MC68000 MOTOROLA [Motorola, Inc], MC68000 Datasheet - Page 83

• Manufacturer Part Number: MC68000
• Manufacturer: MOTOROLA [Motorola, Inc]

3.4 DUAL-PORT RAM
The CP has 1152 bytes of static RAM configured as a dual-port memory. The dual-port RAM
can be accessed by the CP main controller or by one of three bus masters: the M68000 core,
the IDMA, or an external master. The M68000 core and the IDMA access the RAM synchro-
MOTOROLA
Port A Control Register(PACNT
Port A Data Direction Register(PADDR)
Port A Data Register(PADAT)
Port B Control Register(PBCNT)
Port B Data Direction Register(PBDDR)
P
ort B Data Register(PBDAT)
CA
DA
PA
15
15
15
15
15
15
0 = I/O
0 = Input
0 = I/O
0 = Input
CA
DA
PA
RESERVED
RESERVED
14
14
14
1 = Peripheral
1 = Peripheral
CA
DA
PA
13
13
13
1 = Output
1 = Output
RESERVED
CA
DA
PA
12
12
12
12
12
DB
PB
CA
DA
PA
11
11
11
11
11
Figure 3-6. Parallel I/O Port Registers
DB
PB
CA
DA
PA
10
10
10
10
10
MC68302 USER’S MANUAL
DB
PB
CA
DA
PA
9
9
9
9
9
DB
PB
CA
DA
PA
8
8
8
8
8
8
CB
DB
PB
CA
DA
PA
7
7
7
7
7
7
CB
DB
PB
CA
DA
PA
6
6
6
6
6
6
CB
DB
PB
CA
DA
PA
5
5
5
5
5
5
System Integration Block (SIB)
CB
CA
DA
DB
PA
PB
4
4
4
4
4
4
CB
CA
DA
PA
DB
PB
3
3
3
3
3
3
CB
CA
DA
DB
PA
PB
2
2
2
2
2
2
CA
DA
PA
CB
DB
PB
1
1
1
1
1
1
3-33
CA
DA
CB
DB
PA
PB
0
0
0
0
0
0