Commodore 1551 User manual

COMMODORE
1551
DISK DRIVE
USERJS GUIDE
A Friendly Introduction to Your 1551 Diek Drive

The information in this manual has been reviewed and is believed to be entirely reliable.
No responsibility, however,
is assumed for inaccuracies. The material in this manual is
for information purposes only, and may be changed without notice.
© Commodore Electronics Ltd., October 1984
"All rights reserved."

CONTENTS
INTRODUCTION ...................................................... 1
Advantages ofa disk
drive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1
Features ofthe 1551 ..•.•....................................... 1
How to use this book. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
PART ONE: GUIDE TO OPERATION
.................................... 3
CHAPTER 1: DISK DRIVE
.........•................................... 3
Unpacking
........•..................................•........ 3
Connecting the cables . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 4
Turning on the
power. . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
Troubleshooting guide .......................................... 6
Simple maintenance tips. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7
CHAPTER 2: DISKETTES
..............•............................... 9
What
is a diskette? .•...•.......•..........................•.... 9
Safety rules for diskette care
.....•.............................. 10
Using packaged programs .......•.............................. 10
How to prepare a new diskette ...•..........•...............•... 12
Organizing a diskette library. . . . . . . . . . . . . . . . . . . . . . . . . . . . •. . . . . .. 12
Backups ......................•................... ' ........... 13
What is a directory? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13
Viewing a directory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 14
What a directory shows ........................................ 14
CHAPTER 3: OPERATION . . . . . •. . . . . . . •. . . . . . . . . . . •. . . . . . . . •. . . . . . . .. 16
The command channel . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . .. 16
Error checking. . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . .. 17
Error check subroutine ......................................... 17
BASIC housekeeping hints. . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . .. 17
More about directories. . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . .. 18
Selective directories ............................................ 19
Printing a directory. . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 19
Pattern matching and wild cards ................................. 19
Splat files ..•......................•.......................... 20
Verify .•......................•.............................. 22
Copy ..•....•................................................ 23
Scratch •..............•..•....•.......•..............••...... 24
Rename •......................•.............................. 26
Renaming and scratching troublesome files (advanced users) ......... 26
Collect. ....•..•......................•.....................•. 27
Initialize . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . . . .. 28

PART TWO: GUIDE TO ADVANCED OPERATION AND PROGRAMMING 31
CHAPTER 4: SEQUENTIAL DATA FILES ............................... 31
The concept of files ............................................ 31
Opening a file. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 32
Adding to a sequential file .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 34
Writing file data: Print # ....................................... 35
Closing a
file when you are done using it . . . . . . . . . . . . . . . . . . . . . . . . .. 37
Reading file data: Input # ...................................... 38
More about Input # (advanced users) ............................ 39
Numeric data storage on diskettes ................................ 40
Reading file data: Get # ........................................ 41
CHAPTER 5: RELATIVE FILES ................•...................... 44
The value ofrelative access ..................................... 44
Files, records, and fields ........................................ 44
File limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 45
Creating a relative file
.......................................... 45
Using relative files: Record # command
........................... 46
Completing relative file creation
................................. 48
Expanding a relative file. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 49
Writing relative file data ........................................ 50
Designing a relative record. . . . . . . . . . . . . . . . •. . . . . . . . . . . . . . . . . . .
.. 50
Writing the record
....................•........................ 51
Reading a relative record. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53
The value of index files (advanced users) .......................... 54
CHAPTER 6: DIRECT ACCESS COMMANDS
........................... 55
A tool for advanced
users. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 55
Diskette organization .......................................... 55
Opening a data channel for direct access . . . . •. . . . . . . . . . . . . . . . . . . .. 55
Block-read ................................................... 56
Block-write. . . . . . . . •. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.. 57
The original Block-read and Block-write commands . . . . . . . . . . . . . . .. 58
The buffer pointer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 59
Allocating blocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 60
Freeing blocks
....••.......................................... 61
Using random files (advanced users) .............................. 62
CHAPTER 7: INTERNAL DISK COMMANDS .......•.........•.......... 63
1551 memory map .............•............................... 63
Memory-read
................................................. 64
Memory-write
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 65
Memory-execute .........................................•.... 66
Block-execute
...•.........•................•.................. 67
User commands
.••....................•....................... 68

CHAPTER 8: MACHINE LANGUAGE PROGRAMS ...................... 70
Disk-related kernal subroutines .................................. 70
APPENDICES ........................................................ 71
A: Changing the device number ................................. 71
B: DOS error messages and likely causes ...........•............. 73
C: Diskette formats ........................................... 77
D: Disk command quick reference ............................... 82
E: Test/Demo diskette
......................................... 83
F: Specifications of the 1551 disk drive ........................... 86
LIST OF FIGURES
Figure 1:
Front panel
Figure 2: Back panel
Figure 3: Single and twin drive hookup
Figure 4: Position for diskette insertion

INTRODUCTION
The 1551 disk drive greatly increases the speed, storage capacity, flexibility and reliabil-
ity of your Commodore computer. As you use the 1551 disk drive, you will appreciate its
superiority to the cassette recorder you may have used before and to disk drives offered for
other brands
of computers.
THE ADVANTAGES OF A DISK DRIVE
• Speed
If you have used a cassette recorder for data storage, you probably know it can take up
to an hour just to search one long cassette tape looking for a specific program. With the
1551 disk drive, a list of all the programs on a diskette appears on your screen in
seconds. The speed of program loading is also greatly improved. It takes the 1551 only
a minute to load a large program that would take a half-hour to load from tape.
• Reliability
Reliability
is another reason for choosing a disk drive. It is all too common for a cassette
user to accidentally crase a valuable program
by saving a new program on top of the old
one, without realizing it. The
1551 automatically verifies everything it records.
• Direct File Access
A third advantage
of a disk drive is the ability to use relative files (discussed in Chapter
6). On a diskette, any part
of a relative file can be accessed and altered separately,
without affecting the rest
of the file.
Overall, using a disk drive makes for easier and more powerful computing.
FEATURES OF
THE 1551
The
1551 is one of the most affordable disk drives on the market. Compared to
competitors, it has high capacity, and even higher intelligence. It
is one of the most co,t-
effective disk drives available. Most home and personal computers that use a disk take
at
least 10K of RAM memory from the computer to hold a disk operating system (known as
a DOS.) This large program must
be in memory the whole time the disk is being used, and
much
of it must also be kept on every diskette.
The Commodore
1551 works differently and more effectively. It contains its own
built-in microcomputer
to control its various operations, along with enough ROM and
RAM memory to operate without any help from the computer. Commodore's DOS
"lives" entirely inside the disk drive, and does not require any internal memory in the
computer
to do its work, nor does it have to be loaded before use like DOS on other
computers. It
is so independent that once it begins working on a command, it will
complete it while the computer goes on to some other task, effectively allowing you to do
two things at once.
Another key advantage
of the Commodore 1551 overdisk drives for other computers
is its dynamic allocation of disk space. Many other disk drives make you think about
every program you save. Where can I store
it on this diskette, and should I paek the disk

first? (Packing is the process of moving all the leftover work areas to the cnd of the
diskette's storage space.) All this
is handled automatically on Commodore disk drives.
The
1551 always knows where the next program will go, and automatically fits it into the
best available spot.
Diskettes created on the 1551 are read and writc compatible with Commodore 1540/
1541,4040, and 2031 disk drives. That means that diskcttes can be used interchangeably
on any
of these systcms. In addition, the 1551 can read programs created on the older
Commodore 2040 drives.
The
1551 is connected to the computer through the "TCBM" interface. This
interface
is specially created by Commodore. Bytes are transferred as parallel data with a
3-bit bi-directional port, two handshake lines, and two status lines. This handshake
protocol allows for less timing constraint than the slower serial interfaces. Estimated data
rate over the TCBM handshake is 1600 bytes per second versus 300-400 bytes per second
for the
1541 drive. The 1551 connector plugs into the host computer's expansion port and
allows external cartridges to be plugged in. You can have two
1551 drives, two 1541
drives, and two printers hooked up to the computer at once as long as each peripheral is
assigned a different device number. When there is contention with duplicate device
numbers, the
1551 has priority over the 1541.
HOW TO USE THIS BOOK
This book is divided into two main parts. The first part gives you the information you
need to use the
1551 effectively, even if you know little or nothing about programming.
This part
of the book tells you how to set up the system, how to prepare diskettes for use,
how to read a directory, how
to load programs, and various commands. Part two of the
book
is for advanced users and those who would like to become advanced users. This part
provides more advanced commands, tells about the different files the
1551 uses, and how
to manage them, as well as giving a few hints for machine language programmers.
Both beginning and advanced users will
find valuable information in the appendi-
ces-a quick reference list of disk commands, a list of disk error messages and what they
mean, specifications for the
ISS\, how to use two or more disk drives at once, and
explanations
of some programs on the Test/Demo diskette packed with your 1551.
If you are interested only in using pre-packaged programs such as educational or
recreational software, you can turn
to the section entitled "Using packaged programs" in
Chapter 2. First of all, you'll have to hook up your disk drive according to the directions
in Chapter I.
2