Numbers · Architecture · Assembly
Essential Background These topics support the 8086 programming model, registers and pins, number systems, segment:offset memory access, arithmetic and logic instructions, procedures, stack, interrupts, I/O ports, and BIOS/DOS services.
BIN
Binary Number System Bits · powers of two · unsigned values
Microprocessors represent data and instructions as binary bit patterns.
Technical significance
Binary arithmetic is the foundation for registers, memory, opcodes, flags, and digital logic.
Binary Bits Base-2
Be able to convert between decimal and binary and recognize powers of two.
Understand bit positions and place value. Know the ranges of 8-bit and 16-bit unsigned values. Read grouped binary patterns. Connections: registers, opcodes, masks, addresses, flags.
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HEX
Hexadecimal Number System Base-16 · compact binary notation
Hexadecimal provides a compact way to represent binary values.
Technical significance
8086 addresses, machine-code bytes, register values, and bit masks are commonly written in hexadecimal.
Hex Addresses Machine Code
Know decimal↔hex and binary↔hex conversion.
One hex digit represents four bits. Two hex digits represent one byte. Four hex digits represent a 16-bit word. Connections: addresses, memory dumps, opcodes, debugging.
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TC
Signed Numbers & Two's Complement Negative integers · overflow
Processors need a binary encoding for negative integer values.
Technical significance
Two's complement allows the same adder hardware to support signed and unsigned arithmetic.
Two's Complement Signed Overflow
Understand sign bits, two's-complement negation, signed range, and why the same bit pattern can have different signed and unsigned interpretations.Connections: ADD/SUB, Sign Flag, Overflow Flag, conditional jumps.
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BL
Boolean Logic AND · OR · XOR · NOT
Arithmetic and control circuitry is built from Boolean operations.
Technical significance
Logical instructions directly expose many of these operations to assembly programs.
AND OR XOR NOT
Know truth tables and Boolean operators.
AND clears selected bits. OR sets selected bits. XOR toggles or compares bit patterns. NOT complements every bit. Connections: masks, flags, device control, bit fields.
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DL
Digital Logic Basics Gates · multiplexers · flip-flops
A CPU is built from digital circuits that store and transform binary values.
Technical significance
Basic logic concepts make registers, ALUs, buses, and control signals easier to understand.
Logic Gates Flip-Flops MUX
Know combinational versus sequential logic, basic gates, multiplexers, decoders, and flip-flop/register concepts.Connections: ALU, register file, instruction decoder, control unit, status flags.
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PRG
Basic Programming Variables · loops · conditions
Assembly is easier when algorithmic control flow is already familiar.
Technical significance
High-level programming concepts map to lower-level instruction sequences.
Programming Loops Conditions
Be comfortable with assignment, arithmetic expressions, if/else, loops, arrays, and functions.Connections: CMP/Jcc, loops, memory variables, procedures.
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C
C Programming Concepts Types · arrays · functions · memory
C provides a useful bridge between high-level code and assembly.
Technical significance
Many processor concepts become clearer when related to C variables, pointers, function calls, and data sizes.
C Functions Memory
Understand integer types, arrays, functions, and basic pointers even if the course focuses on assembly.Connections: stack frames, calling conventions, data representation, compiler-generated assembly.
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BIT
Bitwise Operations Masks · shifts · rotates
Bit manipulation is fundamental in low-level programming.
Technical significance
8086 includes logical, shift, and rotate instructions specifically for bit-level control.
Masks Shift Rotate
Know bitwise AND/OR/XOR/NOT and left/right shifts.
Build and apply masks. Test individual bits. Understand logical versus arithmetic shifting conceptually. Connections: SHL/SHR, ROL/ROR, device registers, flags.
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CA
Computer Architecture Basics CPU · memory · buses
Microprocessors operate as part of a larger computer system.
Technical significance
Understanding CPU-memory-I/O relationships is essential before studying pins and bus cycles.
CPU Memory Bus
Know the roles of processor, memory, input/output devices, address bus, data bus, and control bus.Connections: 8086 pins, read/write cycles, address/data multiplexing, external devices.
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REG
Registers Fast CPU storage · architectural state
Registers hold operands, addresses, flags, and control state during execution.
Technical significance
The 8086 programming model is organized around general, segment, pointer, index, instruction-pointer, and flag registers.
Registers 8086 State
Understand that registers are small storage locations inside the CPU and are distinct from RAM.Connections: AX/BX/CX/DX, SP/BP/SI/DI, CS/DS/SS/ES, IP, FLAGS.
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MEM
Memory Addressing Addresses · bytes · words
Programs access data through numerical memory addresses.
Technical significance
The 8086 uses segment:offset addressing to generate a 20-bit physical address.
Memory Addressing Segment:Offset
Understand byte-addressable memory and address ranges. For 8086, physical address = segment × 16 + offset.Connections: CS:IP, DS-based data access, SS:SP stack access, memory operands.
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UD
Units of Data Bit · byte · word · kilobyte
Processors manipulate data in fixed-size units.
Technical significance
Data size affects register selection, memory layout, arithmetic range, and instruction behavior.
Bit Byte Word
Know bit, nibble, byte, word, KiB, MiB, and the relationship between 8-bit and 16-bit values.Connections: DB/DW declarations, byte/word operands, register halves AH/AL.
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ASM
Assembly Language Basics Mnemonic · operand · label
Assembly provides symbolic names for machine instructions and operands.
Technical significance
Each assembly instruction maps closely to processor-visible operations.
Assembly Mnemonic Operands
Recognize instruction mnemonics, operands, labels, comments, and assembler directives.Connections: MOV, ADD, SUB, CMP, JMP, CALL, PUSH, POP.
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FDE
Instruction Execution Cycle Fetch · decode · execute
A processor repeatedly fetches, decodes, and executes instructions.
Technical significance
This cycle explains the role of IP, instruction bytes, control logic, and memory access.
Fetch Decode Execute
Understand the conceptual sequence: fetch instruction, decode opcode/operands, execute operation, update architectural state.Connections: IP, instruction queue, bus interface, control unit.
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FLG
Arithmetic Flags Carry · Zero · Sign · Overflow · Parity
Many arithmetic and logical instructions update status flags.
Technical significance
Conditional branches inspect flags rather than re-evaluating previous arithmetic.
FLAGS Carry Overflow
Know the meaning of CF, ZF, SF, OF, and PF at a basic level.
CF is important for unsigned carry/borrow. OF indicates signed overflow. ZF indicates zero result. Connections: CMP, arithmetic, conditional jumps.
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CF
Control Flow Jumps · loops · conditions
Assembly control flow is explicit.
Technical significance
If/else, loops, and switch-like behavior become sequences of comparisons and jumps.
Jumps Loops CMP
Understand conditional and unconditional branches and how CMP affects flags.Connections: JMP, JE/JZ, JNE/JNZ, JC, JO, LOOP.
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PROC
Procedures & Calls CALL · RET · parameters
Procedures provide modular reusable assembly code.
Technical significance
Function calls depend on return addresses, registers, stack discipline, and conventions.
CALL RET Procedures
Understand that CALL transfers control while saving a return address, and RET resumes execution from that saved address.Connections: stack, parameters, saved registers, modular assembly.
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STK
Stack Fundamentals LIFO · PUSH · POP · SP
The stack stores temporary execution state in last-in-first-out order.
Technical significance
Procedure calls and interrupt handling depend heavily on stack discipline.
Stack PUSH POP
Understand LIFO behavior, stack pointer movement, and balanced push/pop operations.Connections: SS:SP, CALL/RET, saved registers, parameters, interrupts.
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INT
Interrupts Events · vectors · ISR
Interrupts transfer control to special service routines in response to events or software requests.
Technical significance
They are central to BIOS/DOS services and hardware event handling.
Interrupts ISR Vector
Understand the idea of saving current execution state, transferring to an interrupt handler, servicing the event, and returning.Connections: interrupt vector table, hardware interrupts, software INT instruction, BIOS/DOS services.
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IO
Input / Output Concepts Ports · devices · control/status
Processors communicate with external devices through registers or I/O ports.
Technical significance
The 8086 includes IN and OUT instructions for isolated I/O space.
I/O Ports Devices
Understand device data, status, and control registers and the difference between memory access and port I/O.Connections: IN, OUT, peripheral interfaces, device polling.
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EL
Basic Electronics Voltage · current · digital levels
Microprocessor pins are electrical signals, not abstract software variables.
Technical significance
Basic electronics knowledge helps interpret clocks, reset, control signals, and device interfaces.
Voltage Signals Clock
Know voltage, current, ground, digital high/low, clock signals, and basic input/output behavior.Connections: processor pins, reset, clock, bus signaling, external circuits.
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CLK
Timing & Clock Clock cycles · frequency · timing
Processors coordinate internal and external operations using clocked timing.
Technical significance
Instruction execution and bus transactions take measurable cycles.
Clock Cycles Timing
Understand frequency, period, and the idea that operations may span multiple clock cycles.Connections: timing diagrams, bus cycles, instruction timing, wait states.
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DBG
Basic Debugging Registers · memory · step execution
Assembly debugging depends on observing machine state directly.
Technical significance
A debugger or emulator makes register, memory, flags, and instruction flow visible.
Debugger Registers Memory
Be comfortable stepping one instruction at a time and inspecting register values, flags, memory, and the stack.Connections: emu8086, tracing, breakpoints, memory dumps, fault isolation.
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