
HYUNDAI MicroElectronics
12
2.2. MEMORY SPACE
All RAM ,ROM,I/O, Peripheral Register are placed in the same memory area. Therefore, same
instructions enable both data transfer and operation without the need to distinguish memory and
I/O. The program counter of GMS81508/16 consists of 16-bit and memory addressing space is 64K
byte.
2.2.1. RAM area
RAM(includes stack area) is 448 Bytes ( 0000
H
01FF
H
).
The internal RAM is used for data storage, subroutine calling or stack area when interrupts occur.
When RAM is used as the stack area, the depth of the subroutine "nesting" and the interrupt levels
should be kept in mind in order to avoid destruction of the RAM contents.
2.2.2. Peripheral Register area
Address 00C0
H
00FF
H
are assigned for peripheral register.
2.2.3. Program ROM area
PCALL subroutines must be located in PCALL area ( FF00
H
FFBF
H
).
TCALL vector area ( FFC0
H
FFDF
H
) has the vector address corresponding to TCALL
instruction.
Interrupt Vector area ( FFE0
H
FFFF
H
) has the vector address of interrupts, inclusive RESET.