The Microcontroller Idea Book - Jan Axelson's Lakeview Research

Chapter 13
EPROM programmer, for storing assembly-language routines or anything else you want to
program into an EPROM, for use on an 8052-BASIC system or another device.
Assembly-language Basics
The bare 8052 chip understands just one language: the binary machine codes that make up
the chip’s instruction set. The 8052’s data book describes the function of each of the machine
codes.
You can, of course, write programs without having to look up binary codes, by using a
programming language. The language that is closest to the machine codes is assembly
language, where a mnemonic, or abbreviation, represents each of the codes.
The assembly-language program that you write is called a source file. After you write a
source file, you must use an assembler to translate the source file into an object file, which
contains the machine codes that the chip will execute. You also must have a way of storing
the object file in the 8052-BASIC system’s memory, where the 8052-BASIC chip can access
it.
The BASIC-52 interpreter is itself an assembled program that the 8052 runs on boot-up. The
interpreter reads your BASIC-52 programs from memory and translates them into machine
codes for the 8052 to execute. It does the same for the BASIC-52 commands that you type
at the keyboard. The interpreter program includes many modular routines that BASIC-52
uses, such as reading a character from the serial port or comparing two values.
BASIC-52 programs are slow for two reasons. One is that the interpreter must translate each
line of code every time it executes it. With assembly language, the assembler translates the
program only once, and the 8052 then reads and executes the binary codes directly from
memory. The other reason for the slowness of BASIC-52 programs is that the nterpreter
program’s translation from BASIC-52 to machine code doesn’t result in the most efficient
code. Programming directly in assembly language gives you much greater control over the
final code that the 8052 will execute.
Incidentally, assembly language isn’t the only way to get faster execution times. Other
options include using a BASIC or C compiler or using a faster crystal to clock the 8052. But
as a rule, these approaches will not speed up programs as dramatically as assembly language.
What You Need
To add assembly-language routines to your BASIC-52 programs, you need several items: a
programming reference with details about the 8052’s assembly language, a text editor for
writing the source files, an assembler to create the executable files, memory in the
8052-BASIC system for storing your programs, and a way to transfer your executable files
218 The Microcontroller Idea Book