Motorola M68CPU32BUG Manuel d'utilisateur télécharger pdf (Page 11)

LAB 3

OBJECTIVES

In this experiment you will:

• Manually produce the machine code and the S-Record for a given assembly program

• Program the CMM-332 board with your own generated code.

INTRODUCTION

Once assembly code is written, an assembler program is used to process the code and

generate the corresponding machine language instructions.

The machine code is the only thing a CPU can execute. The machine code is accessed

by the CPU only after it is loaded in the main memory. A loader program is usually used

to transfer to the machine code to the memory.

Motorola developed the S-record format to facilitate the transfer of data from a computer

to a device (or another computer). For our case the S-record format is used to transfer

data to the CMM332 board.

An S-record ﬁle is a simple ASCII text ﬁle that contains all the necessary information for

the data to be transferred. Such information includes:

• target address location

• length of a block of data

• the data itself

• checksum information to ensure the data is transferred correctly

More detailed information about the S-Record format can be found in Appendix 3.

Once assembly code is generated, the assembler produces the appropriate S-record ﬁle

which can be recognized by the .s or .s19 extension to the ﬁlename. This ﬁle incor-

porates the machine language instructions together with other information that is neces-

sary for loading the machine code into main memory.

For this experiment you can use Appendix 4, the 68000 programmer’s reference manual

as a reference for the op-code of the assembly instructions. Alternatively, the appropriate

section of the textbook may be used as a reference.

PRELAB

The following is to be performed prior to attending the scheduled lab session:

• Read the contents of this lab in its entirety.

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Motorola M68CPU32BUG Manuel d'utilisateur Page 11