7643 Datasheet, PDF (64/121 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

7643 Group
PROCESSOR MODE
Single-chip mode, memory expansion mode, and microprocessor
mode which is only in the mask ROM version can be selected by
using the Processor Mode Bits of CPU mode register A (bits 0 and
1 of address 000016). In the memory expansion mode and micro-
processor mode, a memory can be expanded externally via ports
P0 to P3. In these modes, ports P0 to P3 lose their I/O port func-
tions and become bus pins.
The port direction registers corresponding to those ports become
external memory areas.
Table 8 Port functions in memory expansion mode and
microprocessor mode
Port Name
Port P0
Port P1
Port P2
Port P3
Port P4
Function
Outputs low-order 8 bits of address.
Outputs high-order 8 bits of address.
Operates as I/O pins for data D7 to D0 (including
instruction code).
P30 is the RDY input pin.
P31 and P32 function only as output pins
P33 is the DMAOUT output pin.
P34 is the φOUT output pin.
P35 is the SYNCOUT output pin.
P36 is the WR output pin, and P37 is the RD out-
put pin.
P40 is the EDMA pin.
(1) Single-chip mode
Select this mode by resetting the MCU with CNVSS connected to
VSS.
(2) Memory expansion mode
Select this mode by setting the Processor Mode Bits (b1, b0) to
“01” in software with CNVSS connected to VSS. This mode enables
external memory expansion while maintaining the validity of the in-
ternal ROM.
(3) Microprocessor mode
Select this mode by resetting the MCU with CNVSS connected to
VCC, or by setting the Processor Mode Bits (b1, b0) to “10” in soft-
ware with CNVSS connected to VSS. In the microprocessor mode,
the internal ROM is no longer valid and an external memory must
be used.
Do not set this mode in the flash memory version.
M37643M8
000016
000816
001016
SFR area
SFR area
007016
Internal RAM
047016
000016
000816
001016
007016
SFR area
SFR area
Internal RAM
047016
800016
Internal ROM
FFFF16
FFFF16
Memory expansion mode Microprocessor mode
The shaded areas are external areas.
M37643F8
000016
000816
001016
007016
SFR area
SFR area
Internal RAM
0A7016 _{Reserved area}
100016
800016
Internal ROM
FFFF16
Memory expansion mode
The shaded areas are external areas.
Fig. 61 Memory maps in processor modes other than single-
chip mode
Rev.2.00 Aug 28, 2006 page 64 of 119
REJ03B0054-0200