EM73982
4-BIT MICROCONTROLLER
(2) For instruction LDAM, STAM, STAMI .., HL register used as a pointer for the address of RAM memory.
PROGRAM EXAMPLE: Store immediate data #Ah into RAM of address 35h.
LDL #5h;
LDH #3h;
STDMI #0Ah; RAM[35] ← Ah, LR←6
(3) For instruction : SELP, CLPL, TFPL, L regieter be a pointer to indicate the bit of I/O port.
When LR = 0 indicate P4.0
PROGRAM EXAMPLE: To set bit 0 of Port4 to "1"
LDL #00h;
SEPL ; P4.0 ← 1
STACK POINTER (SP)
Stack pointer is a 4-bit register which stores the present stack level number.
Before using stack, user must set the SP value first, CPU will not initiate the SP value after reset condition.
When a new subroutine is accepted, the SP will be decreased one automatically, in another word, if
returning from a subroutine, the SP will be increased one.
The data transfer between ACC and SP is by instruction of "LDASP" and "STASP" at RAM bank0.
DATA POINTER (DP)
Data pointer is a 12-bit register which stores the address of ROM can indicate the ROM code data
specified by user (refer to data ROM).
* This specification are subject to be changed without notice.
11.30.2001 7