ICS 331: System Software (981)

Quiz # 1

Date: September 20, 1998                                                                                               Time: 20 minutes

Question 1:                                                                                                                                  (6 Points)

a) List three of the common entities in the architectures of the SIC and SIC/XE machines?

    1) The registers A, X, L, PC and SW are common in both machines.

     2) The representation of integers and characters is the same in both machines.

     3) The I/O instructions, TD, RD and WD, are used in both machines.

b) Briefly explain three of the addressing modes used in the SIC/XE machine?

     1) The base-relative mode: TA = (B) + displacement, bits b=1 and p=0.

     2) The indirect mode: TA = ((Displacement)); i. e., the displacement contains the operand address

     3) The immediate mode, the displacement is the operand of the instruction.

Question 2:                                                                                                                                 (14 Points)

Assume that you know that the binary OP code for ADD is 000110, for LDA is 000000, and for STA is 000011
If the contents of PC is 003000 and of X is 000040 Then what is the result of each of the following SIC/XE instruction (HEX):

1) 010005 (000000 010000 0000 0000 0101)

A ¬ 000005 [LDA #5)

2) 1BA00A (000110 111010 0000 0000 1010)

A ¬ 000005 + ((PC)+(X)+displacement)) = 000005+ 000009 = 00000E

3) 0F10C305 (000011 110001 0000 1100 0110 0000 1010)

(C305) ¬ (A) = 00000E

Assume you have the following content of the memory:

00005

000036

•

•

304A

000009

•

•

6350

00C303

•

•

C305