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Technical pages
Assemblers 68000 and 68030
Instructions
Use
Example
Principle
The assembler is a compiler which
allows to write a program by using the specific instructions of
the microprocessor being of use of heart to the computer. The
assembler is indispensable to the writing of the basic instructions
of high-level languages (FORTH, Pascal, C, ...) which are so independen
from the used platform themselves. To speak more technical, high-level
languages are portable while the assembler is not it (unless realize
a simulation software).
The purpose of this page is not to
list all the instructions of processors 68000 and 68030 or to
give a manual of it.
The documentation of the builder is
available on www.motorola.com.
On the other hand, the contents of
this page will allow developers the most warned to realize their
own programs in assembler in the environment of my system.
Instructions
- RAZ_ASSEMBLEUR -
Allows to initialize again the labels table
- ASSEMBLEUR -
Assembly of the text which follows this instruction
until the directive " END "
- FORGET_ASSEMBLEUR -
Allows to remove the instructions set dedicated
to the assembler from the vocabulary.
Use
The assembler of my system is a real
assembler 2 passes managing a labels table. As indicated in the
corresponding column, it contains only 3 instructions FORTH:
- RAZ_ASSEMBLEUR erases the labels
table. This disappearance is automatically realized in the software
installation. It is not necessary to omit the execution of this
instruction at the beginning of the code source because, in case
of assembly again, he will avoid the appearance of the message
" already declared Label ".
- ASSEMBLER crosses the interpreter
FORTH in assembler. From this instruction, the syntax of the
following lines has to follow that of the assembler until the
appearance of the directive " END " which indicates
to the assembler to return to mode interpretation FORTH at the
conclusion of the second pass.
- FORGET_ASSEMBLEUR frees memory occupied
by the assembler when this one is not useful any more. The space
busy report is of 32768 bytes for 68000 and 65536 bytes for the
68030. 3 instruction FORTH bound to the assembler will disappear
of the vocabulary at the same time as the liberation of the memory
space.
Labels have necessarily to begin with
a capital. The following characters can be capitals, numbers or
character "_". Any label of has to begin with the same
letters as the registers of processors.
- 68000 registers: D0, D1, D2, D3,
D4, D5, D6, D7, A0, A1, A2, A3, A4, A5, A6, A7 or SP or USP,
PC, SR, CCR.
- 68030 supplementary registers: ISP, MSP, VBR,
SFC, DFC, CACR, CAAR, TC, CRP, SRP, TT0, TT1, MMUSR.
The registers of the MC68030 (68000
for the mini system) are used in the following way:
Instructions must be written in capitals.
Syntax is the same than that of the MOTOROLA. The modes of addressings
are the following ones:
- 68000 modes of addressings: Dn; An; (An);
(An)+; -(An); (d16,An); (d8,An,Xn); Abs.W; Abs.L; (d16,PC); (d8,PC,Xn);
Imm.
- 68030 supplements: (bd,An,Xn); ([bd,An,Xn],od);
([bd,An],Xn,od); (bd,PC,Xn); (bd,PC,Xn); ([bd,PC,Xn],od).
For the 68030, instructions bound
to coprocessors are not implemented.
Example
To illustrate this presentation, nothing
is worth a good example. This one is available under shape of
file text: sqrt.txt.
It is about a program allowing the
origin of the square root of a positive 32 bits integer.
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