HMS87C5216 Datasheet, PDF (20/76 Pages) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD

HMS87C5216
9.2 Program Memory
A 16-bit program counter is capable of addressing up to 64K
bytes, but these devices have 16K bytes program memory space
only physically implemented. Accessing a location above FFFF_H
will cause a wrap-around to 0000_H.
Figure 9-4, shows a map of Program Memory. After reset, the
CPU begins execution from reset vector which is stored in ad-
dress FFFE_H and FFFF_H as shown in Figure 9-5.
As shown in Figure 9-4, each area is assigned a fixed location in
Program Memory. Program Memory area contains the user pro-
gram.
C000H
F000H
FEFFH
FF00H
FFC0H
FFDFH
FFE0H
FFFFH
TCALL
AREA
INTERRUPT
VECTOR AREA
PROGRAM
MEMORY
PCALL
AREA
Figure 9-4 Program Memory Map
Page Call (PCALL) area contains subroutine program to reduce
program byte length by using 2 bytes PCALL instead of 3 bytes
CALL instruction. If it is frequently called, it is more useful to
save program byte length.
Table Call (TCALL) causes the CPU to jump to each TCALL ad-
dress, where it commences the execution of the service routine.
The Table Call service area spaces 2-byte for every TCALL:
0FFC0_H for TCALL15, 0FFC2_H for TCALL14, etc., as shown in
Figure 9-6.
Example: Usage of TCALL
LDA
#5
TCALL 0FH
:
:
;
;TABLE CALL ROUTINE
;
FUNC_A: LDA LRG0
RET
;
FUNC_B: LDA LRG1 ₂
RET
;
;TABLE CALL ADD. AREA
;
ORG 0FFC0H
DW FUNC_A
DW FUNC_B
;1BYTE INSTRUCTION
;INSTEAD OF 3 BYTES
;NORMAL CALL
1
;TCALL ADDRESS AREA
The interrupt causes the CPU to jump to specific location, where
it commences the execution of the service routine. The External
interrupt 0, for example, is assigned to location 0FFFA_H. The in-
terrupt service locations spaces 2-byte interval: 0FFF8_H and
0FFF9_H for External Interrupt 1, 0FFFA_H and 0FFFB_H for Exter-
nal Interrupt 0, etc.
As for the area from 0FF00_H to 0FFFF_H, if any area of them is not
going to be used, its service location is available as general pur-
pose Program Memory.
Address
0FFE0_H
E2
E4
E6
E8
EA
EC
EE
F0
F2
F4
F6
F8
FA
FC
FE
Vector Area Memory
-
-
ADC Interrupt Vector Area
RC WT Interrupt Vector Area
BIT Interrupt Vector Area
WDT Interrupt Vector Area
-
Timer/Counter 2 Interrupt Vector Area
Timer/Counter 1 Interrupt Vector Area
Timer/Counter 0 Interrupt Vector Area
-
EXT2 Interrupt Vector Area
EXT1 Interrupt Vector Area
KEY SCAN Interrupt Vector Area
-
RESET Vector Area
NOTE:
“-” means reserved area.
Figure 9-5 Interrupt Vector Area
SEP. 2004 Ver 1.01