UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 80

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

3.2 INTERNAL ROM AREA
is accessed, and the overlapping part of the internal ROM area cannot be accessed.
but if the IFCH bit of the memory extension mode register (MM) is set (1), the high-speed fetch function is used and internal ROM
fetches are performed at high speed (2-byte fetch performed in 2 system clocks).
function, but when high-speed fetches are used, wait insertion is not performed for internal ROM. However, do not set external
wait for the internal ROM area. If external wait is set for the internal ROM area, the CPU is deadlocked. This deadlock status
can be cleared only by reset input.
40
The PD784026 subseries products shown below incorporate ROM which is used to store programs, table data, etc.
If the internal ROM area and internal data area overlap when the LOCATION 0 instruction is executed, the internal data area
The internal ROM can be accessed at high speed. Normally, fetches are performed at the same speed as external ROM,
When the instruction execution cycle equal to an external ROM fetch is selected, wait insertion is performed by the wait
RESET input sets the instruction execution cycle equal to the external ROM fetch cycle.
Remark In the case of the ROM-less product ( PD784020, 784021), this address space is external memory.
Product Name
PD784025
PD784026
Internal ROM
48 K
64 K
PD78P4026
CHAPTER 3 CPU ARCHITECTURE
8 bits
8 bits
Location 0 Instruction
00000H-0BFFFH
00000H-0F6FFH
Address Space
Location 0FH Instruction
00000H-0BFFFH
00000H-0FFFFH