38K0 Datasheet, PDF (9/133 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

38K0 Group
[CPU Mode Register (CPUM)] 003B16
The CPU mode register contains the stack page selection bit and
the internal system clock selection bit.
The CPU mode register is allocated at address 003B16.
b7
01
Fig. 7 Structure of CPU mode register
b0
CPU mode register
(CPUM : address 003B16)
Processor mode bits
b1 b0
0 0 : Single-chip mode
0 1:
1 0 : Not available
1 1:
Stack page selection bit
0 : 0 page
1 : 1 page
Not used (returns “1” when read)
(Do not write “0” to this bit)
Not used (returns “0” when read)
(Do not write “1” to this bit)
System clock selection bit
0 : Main clock (XIN)
1 : fSYN
System clock division ratio selection bits
b7 b6
0 0 : φ = f(system clock)/8 (8-divide mode)
0 1 : φ = f(system clock)/4 (4-divide mode)
1 0 : φ = f(system clock)/2 (2-divide mode)
1 1 : φ = f(system clock) (Through mode)
Rev.3.00 Oct 05, 2006 page 9 of 129
REJ03B0192-0300