This document discusses various computer organization and assembly language topics including: - Multiplication and division instructions that can operate on byte, word, and double word operands stored in registers or memory. - Shift instructions like SHR and SHL. - The binary coded decimal (BCD) and ASCII number systems. - Converting between ASCII, unpacked BCD, and packed BCD number representations. - Addition and subtraction instructions for BCD numbers. - Rotate instructions like ROR, ROL, RCR, and RCL. - The INT 10h BIOS interrupt for performing monitor screen functions in text mode like clearing the screen, setting the cursor position, and drawing lines.

1. COMPUTER ORGANIZATION
& ASSEMBLY LANGUAGE
LECTURE # 1 WEEK 11 PRACTICAL
BY MUHAMMAD JAFER
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2. MULTIPLICATION (MUL)
• Byte * Byte
• Operand in AL
• Second Operand Register or Memory
• Result in AX
• Word * Word
• Operand in AX
• Second Operand Register or Memory
• Result in AX,DX
• AX=lower Word, DX=Higher Word
• Word * Byte
• Operand in AL & AH =0
• Results stores in AX & DX
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3. DIVISION (DIV)
• Byte over Byte
• Numerator in AL and AH=0
• Denumerator is in Register or Memory
• Quotient in AL & Remainder in AH
• Word over Word
• Numerator in AX and DX=0
• Denumerator is in Register or Memory
• Quotient in AX & Remainder in DX
• Word over Byte
• Numerator in AX
• Denumerator is in Register or Memory
• Quotient in AL & Remainder in AH
• Double Word over Word
• Numerator in AX (LSW) and DX (MSW)
• Denumerator is in Register or Memory
• Quotient in AX & Remainder in DX
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4. SHIFT
• SHR
• SHL
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5. BCD NUMBER SYSTEM
• Binary Coded Decimal
• Binary representation of 0 to 9
• Two Types
• Unpacked BCD
• Uses 1 Byte for representation
• Lower 4 bit represents the number
• Others are 0
• Packed BCD
• Uses 1 Byte Representation
• Use two set of 4 bytes to represent two
Numbers
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6. ASCII NUMBERS
• Use is same as of BCD
• A standard in USA
• ASCII is in Hexdecimal
• A device that uses ASCII has to communicate
with BCD and vise versa
• Conversions
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7. CONVERSIONS
• Getting rid of 011 from ASCII Number
• ASCII to unpacked BCD
• AND ASCII Number with 00001111 (0F)
• ASCII to packed BCD
• Two ASCII Numbers to one BCD
• Convert two ASCII Numbers to unpacked BCD
• Combine two unpacked BCD to packed BCD
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8. CONVERSIONS
• Getting rid of 011 from ASCII Number
• ASCII to unpacked BCD
• AND ASCII Number with 00001111 (0F)
• ASCII to packed BCD
• Two ASCII Numbers to one BCD
• Convert two ASCII Numbers to unpacked BCD
• Combine two unpacked BCD to packed BCD
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9. ADD AND SUB IN BCD
• DAA
• Use after add
• DAS
• User after sub
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10. ROTATE
• ROR
• ROL
• RCR
• RCL
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11. CHAPTER REVIEW
• The x86 PC Assembly Language, Design &
Interfacing
• Chapter # 3
• Unsigned Addition & Substraction.
• Unsigned Multiplication & Division.
• Logic Instructions
• BCD & ASCII Conversion
• Rotate Instructions
• Bitwise Operation in The C Language
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12. INTERRUPTS (INT)
• Subroutine of BIOS & OS
• INT xxx
• 00 to FF
• 256 interrupts in X86
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13. INT 10H
• Burned into ROM of BIOS
• Associated with monitor screen
• Perform different function based upon value in AH
• Function Performed are
• Clearing Screen
• Change the cursor position
• Change the screen color
• Draw line on screen
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14. MONITOR SCREEN IN TEXT MODE
• 80 columns & 25 rows
• 80 characters wide by 25 character long
• 80 column = 00 to 79
• 25 rows= 00 to 24
• First column is at 00,00
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15. CLEARING SCREEN
• AH=06
• AL=00
• BH=07
• CX=0000
• DH=24
• DL=79
• INT 10H
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16. SET CURSOR LOCATION
• AH=02
• BH=00
• DH=24
• DL=59
• INT 10H
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17. GET CURSOR LOCATION
• AH=03
• BH=00
• INT 10H
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18. CHAPTER REVIEW
• The x86 PC Assembly Language, Design &
Interfacing
• Chapter # 4
• BIOS INT 10H PROGRAMMING
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