1. Registry conditions:

a. Give the unsigned and signed decimal interpretations of each of the following register contents.

* AX contains 7FFEh * BX contains 8543h * AL contains FEh * BL contains 7Fh

b. Show how the decimal integer

* -120 would be stored in 16 bits * -120 would be stored in 8 bits * -32456 would be stored in 32 bits * -32456 would be stored in 16 bits

C. For each of the following decimal numbers, tell whether it could be stored (1) as a 16-bit number (2) as an 8-bit number.

* 32768 * -40000 * 65536 * 257 * -128

D. For each of the following 16-bit signed numbers, tell whether it is positive or negative.

* 1010010010010100b * 78E3h * CB33h * 807Fh * 9AC4h

E. For each of the following instructions, give the new destination contents and the new settings of CF,SF,ZF,PF, and OF. Suppose that the flags are initially 0 in each part of this question. (Note: need not show AF)

* ADD AX,BX where AX contains 7FFFh and BX contains 0001h. * SUB AL,BL where AL contains 01h and BL contains FFh. * DEC AL where AL contains 00h. * NEG AL where AL contains 7Fh. * XCHG AX,BX where AX contains 1ABCh and BX contains 712Ah. * ADD AL,BL where AL contains 80h and BL contains FFh. * SUB AX,BX where AX contains 0000h and BX contains 8000h. * NEG AX where AX contains 0001h.

F. Suppose ADD AX,BX is executed. In each of the following part, the first number being added is the contents of AX, and the second number is the contents of BX. Give the resulting value and tell whether unsigned or signed overflow occurred.

512Ch +4185h ------

FE12h +1ACBh ------

E1E4h +DAB3h ------

7132h +7000h ------

6389h +1176h ------

G. Suppose SUB AX,BX is executed. In each of the following part, the first number is the initial contents of AX and the second number is the contents of BX. Give the resulting value and tell whether unsigned or signed overflow occurred.

2143h -1986h ------

81FEh -19BCh ------

19BCh -81FEh ------

0002h -FEOFh ------

8BCDh -71ABh ------