Technical information

HARDWARE

1-13

3800 GROUP USER’S MANUAL

CPU mode register

The CPU mode register is allocated at address 003B16.

The CPU mode register contains the stack page selection bit.

Fig. 9 Structure of CPU mode register

FUNCTIONAL DESCRIPTION

CPU mode register

(

CPUM : address

003B16)

Stack page selection bit

0 : 0 page

1 : 1 page

Not used (return “0” when read)

Processor mode bits

b1 b0

0 0 : Single-chip mode

0 1 : Memory expansion mode

1 0 : Microprocessor mode

1 1 : Not available