M37754 Mitsubishi, M37754 Datasheet - Page 71

• Manufacturer Part Number: M37754
• Description: SINGLE-CHIP 16BIT CMOS MICROCOMPUTER
• Manufacturer: Mitsubishi

PROCESSOR MODE
Bits 0 and 1 of processor mode register 0 (address 5E
Figure 84 are used to select any mode of the single-chip mode, the
memory expansion mode and the microprocessor mode.
Ports P0 to P3, P10, P11 and a part of port P4 are used as I/O pins
of address, data, and control signals in the modes except the single-
chip mode.
Figure 85 shows the functions of ports P0 to P4, P10 and P11 in
each mode.
The external memory area depends on the mode. Figure 86 shows
the memory map for each mode. Refer to Figure 1 for the addresses
of RAM and ROM in the single-chip mode. The external memory
area can be accessed in the modes except the single-chip mode.
The access to the external memory is affected by the BYTE pin
Fig. 84 Processor mode register 0 bit configuration
7
Note : Clear bit 2 to “0” in low-speed running.
6
0
5
4
3
2
1
M37754M8C-XXXGP, M37754M8C-XXXHP
16
0
) shown in
Processor mode register 0
Processor mode bits
0 0 : Single-chip mode
0 1 : Memory expansion mode
1 0 : Microprocessor mode
1 1 : Do not select.
Internal memory access bus cycle select bit (Note)
; Internal memory access condition in high-speed running
Software reset bit
Reset occurs when writing “1” to this bit
Interrupt priority detection time select bit
0 0 : Select case 0 shown in Figure 13
0 1 : Select case 1 shown in Figure 13
1 0 : Select case 2 shown in Figure 13
Test mode bit
This bit must be fixed to “0.”
Clock
0 : 2- access for internal RAM; 3- access for internal ROM and SFR
1 : 2- access for internal RAM, internal ROM and SFR
0 : No
1 :
1
output
1
output select bit
1
output
• BYTE pin
When accessing the external memory, the level of the BYTE pin is
used to determine whether to use the data bus as 8-bit width or 16-
bit width.
The data bus has a width of 16 bits when the level of the BYTE pin is
“L”, and ports P10 and P11 become the data I/O pins.
The data bus has a width of 8 bits when level of the BYTE pin is “H”,
and port P10 becomes data I/O pins. Port P11 functions then as an
input/output port similarly in the single-chip mode.
When accessing the internal memory, the data bus always has a
width of 16 bits regardless of the BYTE pin level.
M37754S4CGP, M37754S4CHP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Address
5E
16
MITSUBISHI MICROCOMPUTERS
71