An Introduction To 6502 Machine Code (bernard Babani Publishing Radio And Electronics Books) (bernard Babani Publishing Radio & Electronics Books)

June 1986 reprint. [rear cover:] \* In essence, machine code programming is direct programming of the microprocessor without using a built-in high-level computer language such as BASIC. \* The vast increase in running speed obtained when writing programs in machine code is offset, to a degree, by the added complexity in writing them. However, it is not as difficult as one might think and this book tells the story. \* The 6502 microprocessor is utilised in many popular home computers including the Electron, BBC models A and B, VIC-20, ORIC-1/Atmos and the Atari machines. Also, the Commodore 64 uses the 6510 which is a slightly modified but software compatible version of the 6502. \* Some simple demonstration programs which can be run on a number of the above machines are Included in this book. Cover Front CONTENTS Preface Chapter 1. THE MICROPROCESSOR Assembly Languages The Processor Binary Signed Binary Twos Complement Overflow Flag Binary Coded Decimal Hexadecimal System Operation The Stack Flags Paging 6502 Pinouts Memory Organisation Chapter 2. THE 6502 INSTRUCTION SET 1. Add With Carry Mnemonic - ADC 2. Logic AND Mnemonic AND 3. Arithmetic Shift Left Mnemonic ASL 4. Branch On Carry Clear Mnemonic BCC 5. Branch On Carry Set Mnemonic BCS 6. Branch IF (Last Result) Equal To Zero Mnemonic BEQ 7. Test Memory Bits Against Accumulator Mnemonic BIT 8. Branch On Minus Mnemonic BMI 9. Branch On (Last Result) Not Equal To Zero Mnemonic BNE 10. Branch On Plus Mnemonic BPL Break Mnemonic BRK 12. Branch On Overflow Clear Mnemonic BVC 13. Branch On Overflow Set Mnemonic BVS 14. Clear Carry Flag Mnemonic CLC 15. Clear Decimal Flag Mnemonic CLD 16. Clear Interrupt Flag Mnemonic CLI 17. Clear Overflow Flag Mnemonic CLV 18. Compare To Accumulator Mnemonic CMP 19. Compare To X Register Mnemonic CPX 20. COMPARE TO Y REGISTER Mnemonic CPY 21. Decrement Mnemonic DEC 22. Decrement X Register Mnemonic DEX 23. Decrement Y Register Mnemonic DEY 24. Logic Exclusive-0 R Mnemonic EOR 25. Increment Memory Mnemonic INC 26. Increment X Register Mnemonic INX 27. Increment Y Register Mnemonic INY 28. JUMP TO ADDRESS Mnemonic JMP 29. Jump To Subroutine Mnemonic JSR 30. Load The Accumulator Mnemonic LDA 31. Load The X Register Mnemonic LDX 32. Load The Y Register Mnemonic LDA 33. Logical Shift Right Mnemonic LSR 34. No Operation Mnemonic NOP 35. Inclusive Or With Accumulator Mnemonic ORA 36. Push Accumulator Onto Stack Mnemonic PHA 37. Push Processor Status Onto Stack Mnemonic PHP 38. Pull Accumulator From Stack Mnemonic PLA 39. Pull Processor Status From Stack Mnemonic PLP 40. Rotate Left (one bit) Mnemonic ROL 41. Rotate Right (one bit) Mnemonic ROR 42. Return From Interrupt Mnemonic RTI 43. Return From Subroutine Mnemonic RTS 44. Subtract With Carry Mnemonic SBC 45. Set Carry Flag Mnemonic SEC 46. Set Decimal Mode Flag Mnemonic SED 47. Set Interrupt Disable Flag Mnemonic SEI 48. Store Accumulator In Memory Mnemonic STA 49. Store X In Memory Mnemonic STX 50. Store Y In Memory Mnemonic STY 51. Transfer Accumulator To X Mnemonic TAX 52. Transfer Accumulator To Y Mnemonic TAY 53. Transfer Stack Pointer To X Mnemonic TSX 54. Transfer X To Accumulator Mnemonic TXA 55. Transfer X Into Stack Pointer Mnemonic TXS 56. Transfer Y Into The Accumulator Mnemonic TYA Chapter 3. ADDRESSING MODES 1. Implied Addressing 2. Immediate Addressing 3. Absolute Addressing 4. Zero Page 5. Relative Addressing 6. Indirect Addressing Indexed Addressing 7. Absolute Indexed Addressing 8. Indirect Indexed Addressing 9. Indexed Indirect Addressing Chapter 4. STORING AND EXECUTION Execution Chapter 5. EXAMPLE PROGRAMS ADD TAKE LOOP TIMES Note On The BBC/Electron Listings Machine Specific Listings BBC/Electron Versions ADD TAKE LOOP TIMES VIC-20 Versions ADD TAKE LOOP TIMES Commodore 64 Versions ADD TAKE LOOP TIMES ORIC-1 and Atmos Versions ADD LOOP TIMES Chapter 6. INPUT/OUTPUT The 6522 Control Register Instruction Set Chart Cover Back