Binary and hex input/output (in 8086 assembuly langyage)
- 3. Microprocessor Instructor Mam Yumna Bilal
- 4. Group Members Abdul Qayum Imran Khan Adnan Murtaza Usman Mahmood Ahmad Ali M.Shebaz Shreef
- 5. Binary input: For binary Input, we assume a program reads In a binary number from the keyboard, followed by a carriage return. The number actually Is a character string of O's and l's. As each character Is entered, we need to convert it to a bit value, and collect the bits in a register.
- 6. Clear BX /* BX will hold binary value */ Input a character /* '0' or '1' */ WHILE character <> CR DO Convert character to binary value Left shift BX Insert value into 1sb of BX Input a character END_WHILE
- 7. Clear BX BX Input character '1', convert to 1 AND AL,OFH Left Shift BX CF BX Insert value into lsb BX Input character ‘1' , convert to 1 AND AL,OFH Left shift BX CF BX Insert value into lsb BX 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1
- 8. Input character '0' convert to o AND AL,OFH Left shift BX CF BX Insert value into lsb BX = 0000 0000 0000 0110 BX contains 110b The algorithm assumes (1) input characters are either "O", “1", or CR, and (2) at most 16 binary digits are input.AS a new digit Is Input, the previous bits in BX must be shifted to the left to make room; then an OR operation can be used to insert the new bit into BX. 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 00
- 9. XOR BX, BX ; clear BX MOV AH, 1 ;input char function INT 21H ;read a character WHILE_: CMP AL, ODH ;CR? JE END_WHILE ;yes, done AND AL, OFH ;no convert to binary Value SHL BX, 1 ;make room for new value OR BL,AL ;put value into BX INT 21H ;read a character JMP WHILE_ ;loop back END_WHILE:
- 10. Algorithm for Binary Output: FOR 16 times DO Rotate left BX /* BX holds output value, put msb into CF */ IF CF = 1 THEN output ‘1’ ELSE output ‘0’ END_IF, END_FOR
- 11. Mov CX,16 Top: ROL BX,1 JNC Next Mov AH,2 Mov DL,1 JMP Ali Next: Mov DL,2 Mov DL,0 Ali: Int 21H Int Top loop Top
- 12. Hex input consists of digits ("0" to "9") and letters ("A" to "F”) followed by a carriage return. For simplicity, we assume that (1) only uppercase letters are used, and (2) the user inputs no more than four hex characters. The process of converting characters to binary values Is more Involved than it was for binary input. BX must be shifted four times to make room for a hex value.
- 13. Clear BX /* BX will hold input value */ input hex character WHILE character <> CR DO convert character to binary value left shift BX 4 times insert value into lower 4 bits of BX input a character END_WHlLE
- 14. Clear BX BX Input '6', convert to 0110 Left, shift BX 4 times CF BX Insert value into lower 4 bits of BX BX Input 'A', convert to Ah = 1010 Left shift BX 4 times CF BX Insert value into lower 4 bits of BX BX 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 00 0 0 0 0 0 0 0 0 0 1 1 0 1 0 1 0
- 15. Input 'B', convert to 1011 Left shift BX 4 times CF BX Insert value into lower 4 bits of BX BX BX contains 06ABh. Here is the code: XOR BX,BX ;clear BX MOV CL,4 ;counter for 4 shifts MOV AH,1 ; input character function INT 21H ; input a character WHILE_: 0 0 0 0 0 1 1 0 1 0 1 0 0 0 0 00 0 0 0 0 0 1 1 0 1 0 1 0 1 0 1 1
- 16. CMP AL,ODH ;CR? JE END WHILE ;yes, exit ;convert character to binary value AL, 39H ;a digit? CMP AL, 39H ;a digit? JG LETTER. ; no, a letter ; input is a digit AND AL,OFH ;convert digit to binary value JMP SHIFT ;go to insert in BX LETTER: SUB AL, 37H ;convert letter to binary value SHIFT: SHL BX, CL ;make room for new value
- 17. ;insert value into BX CR BL, AL ;put vi!lue into low 4 bits ;of BX INT 21H ; input a character JMP WHILE_ ; loop until CR END_WHILE:
- 18. BX contains 16 bits, which equal four hex digit values. To output the contents of BX, we start from the left and get hold of each digit, convert it to a hex character, and output it. Algorithm for Hex Output: FOR 4 times DO Move BH to DL /* BX holds output value *I Shift DL 4 times to the right IF DL < 10 THEN convert to character in '0' .. '9. ELSE convert to character in 'A' .. 'F‘ END_IF output character Rotate BX left 4 times END FOR
- 19. BX = 4CA9h = 0100 1100 1010 1001 Move BH to DL DL = 0100 1100 Shift DL 4 times to the right DL = 0000 0100 convert to character and output DL = 0011 0100 = 34h = '4' Rotate BX left. 4 times BX = 1100 1010 1001 0100 Move BH to DL DL = 1100 1010 Shift DL 4 times t0 the right DL = 0000 1100
- 20. Convert to character and output DL = 0100 0011 = 43h =‘C’ Rotate BX left 4 times BX = 1010 1001 0100 1100 Move BH to DL DL = 1010 1001 Shift DL 4 times to the right DL = 0000 1010 Convert, to character and output DL = 0100 0010 = 42h ='B' Rotate BX left"4 times BX = 1001 0100 1100 1010 Move BH to DL DL = 1001 0100 Shift DL 4 times to the right DL = 0000 1001 Convert to character and output DL = 0011 1001 =39h = '9' Rotate BX 4 times to the left BX = 0100 1100 1010 1001 = original contents