GMS81504 Datasheet, PDF (19/54 Pages) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

HYUNDAI MicroElectronics
GMS81504
Program Memory
A 16-bit program counter is capable of addressing up
to 64K bytes, but this devices have 4K bytes (8K for
GMS81608) program memory space only the physi-
cally implemented. Accessing a location above FFFFH
will cause a wrap-around to 0000H.
Figure 8, shows a map of the upper part of the Program
Memory. After reset, the CPU begins execution from
reset vector which is stored in address FFFEH, FFFFH.
As shown in Figure 8, each area is assigned a fixed
location in Program Memory. Program Memory area
contains the user program, Page Call (PCALL) area
contains subroutine program, to reduce program byte
length because of using by 2 bytes PCALL instead of
3 bytes CALL instruction. If it is frequently called,
more useful to save program byte length.
F000H
PROGRAM
MEMORY
FEFFH
FF00H
FFBFH
FFC0H
FFDFH
FFE0H
FFFFH
PCALL
AREA
TCALL
AREA
INTERRUPT
VECTOR
AREA
Figure 8. Program Memory
Table Call (TCALL) causes the CPU to jump to each
TCALL address, where it commences execution of the
service routine. The Table Call service locations are
spaced at 2-byte interval : FFC0H for TCALL15,
FFC2H for TCALL14, etc.
Address
FFC0H
FFC2H
FFC4H
FFC6H
FFC8H
FFCAH
FFCCH
FFCEH
FFD0H
FFD2H
FFD4H
FFD6H
FFD8H
FFDAH
FFDCH
FFDEH
TCALL Name
TCALL15
TCALL14
TCALL13
TCALL12
TCALL11
TCALL10
TCALL9
TCALL8
TCALL7
TCALL6
TCALL5
TCALL4
TCALL3
TCALL2
TCALL1
TCALL0/ BRK¹⁾
1) The BRK software interrupt is using same address with
TCALL0.
The interrupt causes the CPU to jump to specific
location, where it commences execution of the service
routine. The External interrupt 0, for example, is as-
signed to location FFFAH. The interrupt service loca-
tions are spaced at 2-byte interval : FFF8H for External
Interrupt 1, FFFAH for External Interrupt 0, etc.
Any area from FF00H to FFFFH, if it not going to be
used, its service location is available as general pur-
pose Program Memory.
Address
FFE0H
FFE2H
FFE4H
FFE6H
FFE8H
FFEAH
FFECH
FFEEH
FFF0H
FFF2H
FFF4H
FFF6H
FFF8H
FFFAH
FFFCH
FFFEH
Vector Name
-
-
-
Basic Interval Timer
-
Analog to Digital Converter
-
-
Timer/ Counter 1
Timer/ Counter 0
-
-
External Interrupt 1
External Interrupt 0
-
RESET
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