1. Assembly Language (continue)
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2. Assembly Language Format
Label Opcode Operand Comment
Start : LXI SP,3FF0H ;Initialize stack pointer
Delimiter Placement
Colon After label
Space Between an opcode and an operan
Comma Between two operand
Semicolon Before beginning of a comment
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3. Assembler Directive Assembler Example Description Directive
ORG (Origin) ORG 2000H The next block of instructions should store in memory
starting at 2000H
END END End of assembly
EQU PORTA: EQU 80H The value of term PORTA is equal to 80H
DFB (define byte) DATA: DFB 10H,30H Initializes an area byte by byte
DFW (define Word) DATA: DFW 2020H Initializes an area two byte at time
DFS (define Storage) DATA: DFS 10 Reserves a specified number of memory
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4. Flowchart : Program Assembly & Execution
Write /Edit Source Program
Assemble Source File
Errors?
Generate Hex / List File
Download Hex File into Target System & Execute Program
Expected Result?
Troubleshot/Debug
Go Back to Edit Errors
Start
End
Yes No
Yes No
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5. Example (Sample Source Code)
CPU “8085.TBL”
ORG 2000H
NUM1: EQU 55H
NUM2: EQU 78H
LXI SP, 3FF0H ;Initialize Stack pointer
MVI A, NUM1 ;load first number
MOV B,A ;save it to B register
MVI A, NUM2 ;load second number
ADD B ;add register A & B
STA RESULT ;store to 2050H
RST 1
ORG 2050H
RESULT: DFS 1 ;reserve 1 byte location in
END ;memory
(Note: write your source code using any text editor)
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6. Manual assembly *Please Refer to 8085 Assembly Code Summary
FLAGS _
INSTRUCT LOGICAL OP-CODE BYTE T-STATE S Z P CY AC
MOV B,A (B)(A)
LXI SP, data16 (SP)  (byte 3)
(SP)  (byte 2)
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7. Manual assembly Address (Hex) Program Code Machine Code (Hex) 2000
LXI SP, 3FF0H
31 F0 3F
2003
MVI A, NUM1
3E 55
2005
MOV B,A 47
2006
MVI A, NUM2
3E 78
2008
ADD B 80
2009
STA RESULT
200C
RST 1 CF
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8. Exercise CPU “8085.TBL” ORG 2000H PORTA: EQU 80H
LXI SP, 3FF0H ;Initialize Stack pointer
XRA A
LOOP: CMA
OUT PORTA
CALL DELAY
JMP LOOP
DELAY: MVI B, 255
LOOP1: DCR B
JNZ LOOP1
RET
END
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9. Manual assembly Address (Hex) Program Code Machine Code (Hex)
LXI SP, 3FF0H
XRA A
CMA
OUT PORTA
CALL DELAY
JMP LOOP
MVI B, 255
DCR B
JNZ LOOP1
RET
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10. Assembler
The Assembler is a program that translates source code or mnemonics into the binary code (machine code).
In addition to translating mnemonics, the Assembler performs various functions, such as error checking and memory allocations.
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11. Source File (Example.ASM) Assembler (Translator) HEX File Listing File
(Example.HEX)
Listing File
(Example.LST)
Assembler
(Translator)
Source File
(Example.ASM)
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12. Example of Listing File
CPU "8085.TBL"
ORG 2000H
= NUM1: EQU 55H
= NUM2: EQU 78H
F03F LXI SP, 3FF0H ;Initialize Stack pointer
E MVI A, NUM1 ;load first number
MOV B,A ;save it to B register
E MVI A, NUM2 ;load second number
ADD B ;add register A & B
STA RESULT ;store to 2050H
0200C CF RST 1
ORG 2050H
RESULT: DFS 1 ;reserve 1 byte location in
END ;memory
NUM1
NUM2
RESULT
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13. Data Byte (Program Code)
Example of Hex File
: FC
:0D F03F3E55473E CFF2
: FF
Byte Count
Record Type
Data Byte (Program Code)
Checksum
Address
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14. The number of data bytes in the record Address
Byte Count
The number of data bytes in the record
Address
Address of the first data byte in the record.
Address in End of File record is 0000
Record Type
The record type for a data record is 00. The record type for an End
of File record is 01
Data Byte
Data byte in HEX ASCII. Two character per byte.
Checksum
Two’s complement byte of binary sum of preceding byte in record;
Including byte count, address and data byte
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15. Testing & Debugging
Download Hex File into Target System & Execute Program
8085 Development System is communicated with PC through
serial port (RS232).
8085 Development Board PC
RS232
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