Riassunto
The Apple / / series of computers represents one of the most versatile and powerful home computers available. If you've used your computer for a while, you've probably become quite familiar with Applesoft BASIC. That's good, because once you know that, this book will show you how to graduate from BASIC programming to assembly language programming. There are many reasons to program your Apple in assembly language. First and foremost is speed. Assembly language is about 100 times faster than BASIC. If you're thinking of writing games or business programs that do sorting, speed is of the essence and assembly language is a must. Assembly language programs usually also require less memory. Thus you can squeeze more complex programs into a smaller amount of memory. Finally, assembly language programs offer you a considerable amount of security, because they are more difficult to trace and change. While assembly language is powerful, it doesn't have to be difficult to learn. In fact, if you can write programs in Applesoft BASIC, you're already half-way home. This book assumes you know BASIC and absolutely nothing about assembly language or machine language. Every effort has been made to write in nontechnical language and to set the chapters out in a logical manner, introducing new concepts in digestible pieces as and when they are needed, rather than devoting whole chapters to specific items.
Contenuti
1 Machine Code or Assembly Language.- (Why machine code?).- 2 Numbers.- (Binary, hex and decimal, Binary to decimal conversion, Decimal to binary conversion, Binary to hex conversion, Hex to decimal conversion).- 3 It All Adds Up!.- (Binary arithmetic, Addition, Subtraction, Binary coded decimal (BCD), BCD addition, BCD subtraction).- 4 It’s Logical.- (Logical operations, AND, OR, EOR).- 5 The Registers.- (The accumulator, The index registers, The program counter).- 6 A Poke at Machine Code.- (Code —the program counter, Entering machine code, The hex loader program, Calling machine code, Saving it out to disk, The Apple ROMs.- 7 Status Symbols.- (The status register).- 8 Addressing Modes I.- (Zero page addressing, Immediate addressing).- 9 Bits and Bytes.- (Load, store and transfer, Paging memory).- 10 Arithmetic in Assembler.- (Addition, Subtraction, Negation, Using BCD).- 11 Addressing Modes II.- (Absolute addressing, Zero page indexed addressing, Absolute indexed addressing, Indirect addressing, Post-indexed indirect addressing, Pre-indexed absolute addressing, Implied and relative addressing).- 12 Stacks of Fun.- (The stack, Stack instructions for saving data).- 13 Looping.- (Loops, Counters, Comparisons, Branches, FOR ... NEXT, Memory counters).- 14 Subroutines and Jumps.- (Subroutines, Passing parameters, Jumps).- 15 Shifts and Rotates.- (Arithmetic shift left, Logical shift right, Rotate left, Rotate right, Logically speaking, Printing binary!, BIT).- 16 Multiplication and Division.- (Multiplication, Division).- 17 Assembly Types.- (Conditional assembly, Look-up tables).- 18 Floating a Point.- (The floating point accumulators, Using USR, Integer to floating point, Floating point to integer, Floating memory, The subroutines).- 19 Speeding Up and Slowing Down.- 20 Interrupts and Breaks.- (Interrupts, Breaks).- 21 Prepacked Utilities.- (Hex to binary conversion, Binary to hex conversion, Output ASCII string).- Appendices.- 1 The Screen.- 2 The 6502 and 65C02.- 3 The Instruction Set.- 4 Instruction Cycle Times.- 5 Apple // Memory Map.- 6 Branch Calculators.- 7 6502 and 65C02 Opcodes.- General Index.- Program Index.
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