gc80c520a CORERIVER Semiconductor, gc80c520a Datasheet - Page 91

• Manufacturer Part Number: gc80c520a
• Description: Midas1.0 Family Mask Rom/eprom/romless 8-bit Turbo Microcontrollers
• Manufacturer: CORERIVER Semiconductor

ACALL
Description:
Operation:
Encoding:
MiDAS1.0 Family
Function:
Example:
addr11
Cycles:
Bytes:
Absolute Call
ACALL unconditionally calls a subroutine located at the indicated address.
The instruction increments the PC twice to obtain the address of the following
instruction, then pushes the 16-bit result onto the stack (low-order byte first)
and increments the Stack Pointer twice. The destination address is obtained
by successively concatenating the five high-order bits of the incremented PC,
opcode bits 7-5, and the second byte of the instruction. The called subroutine
must therefore start within the same 2K block of the program memory as the
first byte of the instruction following ACALL. No flags are affected.
Initially SP equals 07h. The label “SUBRTN” is at program memory location
0345h. After executing the instruction,
ACALL SUBRTN
at location 0123h, SP will contain 09h, internal RAM locations 08h and 09h
will contain 25h and 01h, respectively, and the PC will contain 0345h.
2
3
ACALL
(PC)
(SP)
((SP))
(SP)
((SP))
(PC
a10 a9 a8 1
10-0
←
←
←
←
←
)
(SP) + 1
(SP) + 1
(PC)+ 2
←
(PC
(PC
page address
7-0
15-8
)
)
0 0 0 1
Page 91 of 187
a7 a6 a5 a4
a3 a2 a1 a0