Delta DVP-ES2/EX2/SS2/SA2/SX2/SE manual 14 E, F Index Registers, Index register E, F, Call

2. Programming Concepts

2.14 E, F Index Registers

Index registers are used as modifiers to indicate a specified device (word, double word) by defining an offset. Devices can be modified includes byte device (KnX, KnY, KnM, KnS, T, C, D) and bit device (X, Y, M, S). E, F registers cannot be used for modifying constant (K, H) Index registers not used as a modifier can be used as general purpose register.

Index register [E], [F]

Index registers are 16-bit registers which can be read and written. There are 16 points indicated as E0~E7 and F0~F7. If you need a 32-bit register, you have to designate E. In this case, F will be covered up by E and cannot be used. It is recommended to use instruction DMOVP K0 E to reset E (including F) at power-on.

16-bit		16-bit
F0		E0
	32-bit

F0

E0

High word Low word

The combinations of E and F when designating a 32-bit register are:

(E0, F0) , (E1, F1) (E2, F2) (E3, F3) (E4, F4) , (E5, F5) (E6, F6) (E7, F7)

Example:

When X0 = ON and E0 = 8, F0 = 14, D5E0 = D(5+8) = D13, D10F0 = D(10+14) = D24, the content in D13 will be moved to D24.

X0

MOV K8 E0

MOV K14 F0

MOV D5E0 D10F0

2.15 Nest Level Pointer[N], Pointer[P], Interrupt Pointer [I]

	N	Master control nested	N0~N7, 8 points	The control point of
				master control nested
Pointer
	P	For CJ, CALL instructions	P0~P255, 256 points	The location point of CJ,
				CALL

2 - 5 1