Syntax:

• ISUB Rd BS Rs0 Rs1

Description:

Subtracts the contents of Rs2 from contents of Rs1, and moves the result to Rd according to BS (bank select). Instruction is stack conditioned.

Microcode Pattern:

Takes 5 cycles to execute.
    Example: ISUB 0xA3 3 0xA0 0xA1

	  
	MPC   BS3 C3 P3 P1 P0
	---------------------
	ISUB   0  0  00 A1 A0
	  -    0  0  00 00 00
	  -    0  0  00 00 00
	  -    0  0  00 00 00
	  -    3  0  A3 00 00

	  

Exceptions :

No exceptions.

Example :

ISUB 0x20 0 0x22 0x21 ! Subtract content of register 0x21
                      ! from content of register 0x22 and
                      ! don't write the result to
                      ! register file

ISUB 0x20 1 0x22 0x21 ! Subtract content of low bank of
                      ! registers 0x21 from content of
                      ! low bank of register 0x22 and move
                      ! the result in low bank of
                      ! register 0x20

ISUB 0x20 2 0x22 0x21 ! Subtract content of high bank of
                      ! registers 0x21 from content of
                      ! high bank of register 0x22 and move
                      ! the result in high bank of
                      ! register 0x20

IADD 0x20 3 0x22 0x21 ! Subtract content of register 0x21
                      ! from content of register 0x22 and
                      ! move result to register 0x20