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This session covers essential concepts of Assembly language and microprocessor operations. Explore binary numbers, two's complement arithmetic, and fundamental programming structures. We will discuss memory designators, labels, registers, flags, and operations necessary for effective low-level programming. The interactive model of a hodometer will demonstrate binary addition and bitwise manipulation. Additionally, we will focus on assembler directives, generic instructions, and debugging techniques, providing a comprehensive overview for anyone looking to delve into microprocessor programming.
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Assembly Microprocessorssession 2 ing. Ernst E. Mak MSc
Contents: • Binary numbers, Addition, Subtraction, Two’s complement • Starting Deeds, Board, Dipswitches, Editor, Debugger • programming structure: • Assembly directive: ORG memory designator • Labels • Statements • Operands • Comments • Deeds Help function • Registers, Flags, Memory, Decimal and Hexadecimal
X-ary Numbers • X = base number of the number system • consist of symbols 0.......(X-1) • QUESTION: Why not 0.....X ???? Adjacent digits (from right to left) represent increasing powers of the X-ary system
0 0 0 9 9 9 1 1 1 8 8 8 2 2 2 3 3 3 7 7 7 4 4 4 6 6 6 5 5 5 MODEL : hodometer
HODOMETER (2) • What was the X? • How many symbols per disc ? • Maximum number? • Now imagine a BINARY disc into the hodometer • write down the first 20 numbers • ? how many discs did you need?
0 0 0 1 1 1 MODEL : hodometer
Addition 1 0 1 0 0 0 0 1 0 1 0 0 0 1 0 1 + 1 1 1 0 0 1 1 0
Negative Numbers Using the 8-th bit as a SIGN bit 53 = 0 0 1 1 0 1 0 1 -53 = 1 0 1 1 0 1 0 1 Inverting the bits 53 = 0 0 1 1 0 1 0 1 -53 = 1 1 0 0 1 0 1 0
Two’s Complement 13 0 0 0 0 1 1 0 1 inv 1 1 1 1 0 0 1 0 1 +1 Two’s Complement 1 1 1 1 0 0 1 1
Two’s Complement (2) 61 0 0 1 1 1 1 0 1 Two’s Complement 13 1 1 1 1 0 0 1 1 + 1 0 0 1 1 0 0 0 0 48
Flags • Carry • Overflow • Zero • Negative • .. • … • ...
Generic Instructions • Input/output data • Load a value (register) into a register • Arithmetic • jumping / subroutine • control • Bitwise operators : Boolean, Register shifts • interrupt handling • stacking
ASSEMBLY-LAY-OUT {LABEL:} [tab] OPCODE [tab] {OPERANDS} [tab] {; remark-line} examples: start: JP 100 ; go to program start loop: JR NC,-10 ; Loop back if not carry AND A,32 ; reset 6th bit in accumulator HALT ; stop execution ; this is a remark line without operation
MNEMONIC • “short-hand” • examples: • add a,10 ;add 10 into the a register • jp 155 ;jump to a location • inc H ;increase the h register by one
ASSEMBLER DIRECTIVES • ORG xxx • lable DW 122 • lable2 DB 10 • organize next code starting at memory location xxxx • define a value 122 into a word type of variable called ‘lable’ • define a value 10 into a byute type variable called ‘lable2’
ASSEMBLER CYCLE text file start: ORG 100 begin: jp 130 add a,3 loop: nop nop inc bc .... ..... LINK ROUTINE modules MEMORY 11010010;10011000;00011101;11101010;11101110;11110110;10100111;01000011;11110000;01100000;10101011;10111000;01111101;11000011;10110111;00010101;01111111;01000010;01000000;11000101;11011110;10110111;01000000;11011101;10011000;10110110; ASSEMBLER LINKER TEXT EDITOR DEBUGGER MICRO PROCESSOR input output
Main registers. Alternative registers. Accumulator Registers Interupt register Alternative Registers Memory Refresh Adress Registers Z80 Processor Register Layout I A’ A F F’ R W Z W’ Z’ B C B’ C’ D E D’ E’ Flags 8 bit H L H’ L’ S Sign Z Zero I X - - H Half-Carry I Y - - S P P/V Parity/overfl. P C N Negate C Carry
