The content of the Program Counter and Accumulator Register in a basic computer at time T are 43B and 5EF7 respectively. At the same time, if the content of memory at address 43B, 5AB, and 6C2 are 95AB, 06C2, and 65AB respectively, then answer the following questions (all the numbers are in Hexadecimal):
i) Draw a diagram that shows the memory status before execution of the instruction;
ii) State the contents of the Program Counter, Address Register, Data Register, and Accumulator Register at the end of the instruction execution;
iii) State the mode of address used in the instruction and discuss the advantage and disadvantage of using this mode of address.
Table 1: Basic Computer Instructions Hexadecimal code
Description
External (MAP)
Symbol 1=0 1=1
AND ADD LDA STA BUN BSA ISZ
Oxxx 1xxx 2xxx 3xxx 4xxx 5xxx 6xxx
8xxx AND memory word to AC 9xxx Add memory word to AC XXXV Load memory word to AC Bxxx Store content of AC in memory Cxxx Branch unconditionally Dxxx Branch and save return address Exxx Increment and skip if zero