Designing a Logic Instruction to be Placed in ROM KEY
You have been assigned to assist Tony and his team in designing a portion of the ROM chip for the Basic Computer 2000. The team has decided that the ROM chip will reside at memory addresses 0 through 99h and that the much needed OR instruction will start at address 4Fh. Other decisions that have already been made include standardization of memory allocation: Test programs will start at address 100h, operands will start at 200h, and the test program will write to memory beginning at 300h.
You have been assigned the task of completing the OR instruction lines 4Fh and 58h that will be hardwired into ROM and writing a short program to call this routine starting at line 100h. Place your operands on lines 200h and 201h, using 2101110 and 1282110 as your initial operands. Trace through your program recording memory writes in the appropriate 300h address. Your program will utilize the BSA and BUN instructions. Fill in the Binary Instruction Code (Hex), Symbolic Instruction, and Register Transfer Statements for any lines of code that are not operands.
|
Address (Hex) |
Binary Instruction Code (Hex) |
Symbolic Instruction |
Register Transfer Statements |
|
4F |
|||
|
50 |
2200 |
LDA A |
DR ¬ M[AR] |
|
51 |
7200 |
CMA |
AC ¬ (AC)', SC ¬ 0 |
|
52 |
3300 |
STA |
M[AR] ¬ AC, SC ¬ 0 |
|
53 |
2201 |
LDA B |
DR ¬ M[AR] |
|
54 |
7200 |
CMA |
AC ¬ (AC)', SC ¬ 0 |
|
55 |
0300 |
AND |
DR ¬ M[AR] |
|
56 |
7200 |
CMA |
AC ¬ (AC)', SC ¬ 0 |
|
57 |
3301 |
STA |
M[AR] ¬ AC, SC ¬ 0 |
|
58 |
|||
|
100 |
|||
|
7001 |
HALT |
S ¬ 0 /Halt computer |
|
|
200 |
operand A |
|
|
|
201 |
operand B |
|
|
|
300 |
operand A' |
|
|
|
301 |
operand A Ú B |
|