6502 Programming tips and code fragments

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Bit and flag manipulation BitManip Copying, clearing, setting and rotating bits SwapVals Swapping data without temporary variable FlagManip Setting and clearing flags Arithmetic Decrement  16-bit, 24-bit, 32-bit, etc. decrement Counting Unusual counting Conversion and calculations BCD  Converting 8-bit Binary Coded Decimal SqRoot  Calculate integer Square Root 60to100  Multiply by 1.66 to convert 1/60ths to 1/100ths Times60  Routines to multiply by 60 and 100 Divide60  Routines to divide by multiples of 60 and 100 Denormal Denormalising floating point numbers 6502Divide  Routines to divide by various constants Stack manipulation StackWS  Using stack for workspace StackWS.src (L)  Demo of using stack for workspace StackMem  Subroutines to stack memory Dates and Time DayOfWeek  DofWeek (L) Calculating day of week for 1900-2155 DayOfWk16a  DofWeek16a (L) Calculating day of week for any 16-bit year DayOfWk16b  DofWeek16b (L) DateUpdate Incrementing a date to the next month

Printing MCode  Printing inline strings Displaying numbers PrNumber Printing 8-bit numbers in hex and decimal PrtDecimal Compact arbitary size decimal printout PrDecimal  PrDecDemo (L)  Printing 16/24/32-bit numbers in decimal Decimal printout BASIC source and test code Scanning (reading in) numbers ScanNumber  Scanning 8-bit hex and decimal numbers ScanDecNum  Scanning 16/24/32-bit decimal numbers CRC calculation CRC-8 Calculating 8-bit CRCs CRC16  Calculating 16-bit CRCs for XMODEM and Acorn CFS/RFS CRC32  Calculating 32-bit CRCs for ZIP files Hardware I/O ps2kbd1.asm Update of Daryl Rictor's polled PS/2 keyboard driver Testing  RAM tester Programs and tools BBCBasic  BBC BASIC for the 6502 DisAssem  BBC BASIC 6502 disassembler 6502  6502 assembler for ARM BBC BASIC BeebAsm  BeebAsm 6502 assembler BBC 6502 programming BBC/ProgTips  BBC 6502 programming tips CatchingErrors  Catching errors

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Authored by J.G.Harston
Last update: 12-Mar-2023