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CENTRAL PROCESSING UNIT (CPU)

7733 Group User’s Manual

2–18

2.4 Memory allocation

The internal area’s memory allocation is described below. For the external area, refer to section “2.5

Processor modes.”

2.4.1 Memory allocation in internal area

SFR (Special Function Register), internal RAM, and internal ROM are allocated in the internal area.

(1) SFR (Special Function Register) area

Registers required for setting internal peripheral devices are allocated to addresses 016 to 7F16. This

area is called “SFR (Special Function Register) area.” Figure 2.4.4 shows the SFR area’s memory

map.

For each register in the SFR area, refer to the corresponding functional description.

For the state of the SFR area immediately after reset, refer to section “13.1.2 State of CPU, SFR area

and internal RAM area.”

(2) Internal RAM area

In the M37733MHBXXXFP, a 3968-byte static RAM is allocated to addresses 8016 to FFF16 (Note).

The internal RAM area is used as a data store area and as a stack area. Therefore, it is necessary

to give careful consideration to nesting levels in subroutines and multiple interrupts’ levels not to

destroy necessary data.

(3) Internal ROM area

In the M37733MHBXXXFP, a 124-Kbyte mask ROM is allocated to addresses 100016 to 1FFFF16

immediately after reset (Note). The internal ROM’s size and area can be changed by the memory

allocation selection bits (bits 0 to 2 at address 6316). Figure 2.4.1 shows the structure of the memory

allocation control register and its setting method. Figures 2.4.2 and 2.4.3 show the M37733MHBXXXFP’s

memory map. (Refer to section “Appendix 9. Q & A.”) Vector addresses for reset and interrupts

(interrupt vector table) are allocated to addresses FFD616 to FFFF16 in the internal ROM. In the

microprocessor mode, where the internal ROM area is inhibited from use, the ROM must be allocated

to addresses FFD616 to FFFF16.

Note: For the other microcomputers of the 7733 Group, refer to section “Appendix 1. Memory allocation

of 7733 Group.”

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