Download MARIE Instruction Set Architecture (ISA)

MARIE Assembly Language
Type of
Instructions
Arithmetic
Data Transfer
I/O
Branch
Mnemonic
Hex
Opcode
3
4
B
ADD X
SUBT X
ADDI X
CLEAR
LOAD X
STORE X
INPUT
OUTPUT
JUMP X
SKIPCOND C
Description
Add the contents of address X to AC
Subtract the contents of address X from the AC
Add Indirect: Use the value at X as the actual address of the
data operand to add to AC
Put all zeros in the AC
Load the contents of address X into AC
Store the contents of AC at address X
Input a value from the keyboard into AC
Output the value in AC to the display
Unconditional branch to X by loading the value of X into PC
Skip the next instruction based on the condition, C:
(b11b10 = 002)
C = 00016: skip if AC is negative
C = 40016: skip if the AC = 0
(b11b10 = 012)
C = 80016: skip if the AC is positive (b11b10 = 102)
Jump-and-Store: Store the PC at address X and jump to X+1
Use the value at X as the address to jump to
Terminate the program
A
1
2
5
6
9
8
Subroutine
JNS X
call and return JUMPI X
HALT
0
C
7
MARIE
Instruction
Format
15
12 11 10
Opcode
0
Address (or Condition)
Revised Figure 4.9 Datapath in MARIE
1
MAR
2
PC
3
4
7
5
6
16
1
2
3
MBR
AC
IR
InREG
OutREG
Memory
address
ALU
data/instr.
Address
0
1
2
3
16-bits
4
2
7
5
6
Input
Device
Output
Device
12
-1
MARIE Assembly Language Example 1: RESULT = X + Y - Z
Address Label
Assembly Language
Machine Language
0
LOAD X
100616
1
ADD Y
300716
2
SUBT Z
400816
3
STORE RESULT
200916
4
OUTPUT
600016
5
HALT
700016
6
X,
DEC 10
000A16
7
Y,
DEC 20
001416
8
Z,
DEC 5
000516
9
RESULT,
DEC 0
000016
MARIE Assembly Language Example 2: Print null terminated string to output
HLL: index = 0
while str[index] != 0 do
output str[index]
index = index + 1
end while
Address
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
10
11
12
13
14
15
16
17
18
19
1A
1B
1C
1D
1
1F
Label
WHILE,
DO,
END_WHILE,
ONE,
INDEX,
ADDR,
STR_BASE,
STR,
NULL,
Assembly Language
CLEAR
STORE INDEX
LOAD STR_BASE
ADD INDEX
STORE ADDR
CLEAR
ADDI ADDR
SKIPCOND 400
JUMP DO
JUMP END_WHILE
OUTPUT
LOAD INDEX
ADD ONE
STORE INDEX
JUMP WHILE
HALT
DEC 1
DEC 0
HEX 0
HEX 14
DEC 72 / H
DEC 69 / E
DEC 76 / L
DEC 76 / L
DEC 79 / O
DEC 13 /carriage return
DEC 87 / W
DEC 79 / O
DEC 82 / R
DEC 76 / L
DEC 68 / D
DEC 0
/ NULL CHAR
Machine Language
A00016
201116
101316
301116
201216
A00016
B01216
840016
900A16
900F16
600016
101116
301016
201116
900216
700016
000116
000016
000016
001416
004816
004516
004C16
004C16
004F16
000D16
005716
004F16
005216
004C16
004416
000016