Commodore 1581 User manual

COMMODORE
n
DISK DRIVE
useris guide
v
■

USER'S MANUAL STATEMENT
WARNING: This equipment has been certified to comply with the limits for
a Class B computing device, pursuant to subpart J of Part 15 of the
Federal Communications Commission's rules, which are designed to pro
vide reasonable protection against radio and television interference in a
residential installation. If not installed properly, in strict accordance with
the manufacturer's instructions, it may cause such interference. If you
suspect interference, you can test this equipment by turning it off and on. If
this equipment does cause interference, correct it by doing any of the
following:
• Reorient the receiving antenna or AC plug.
• Change the relative positions of the computer and the receiver.
• Plug the computer into a different outlet so the computer and
receiver are on different circuits.
CAUTION: Only peripherals with shield-grounded cables (computer input-
output devices, terminals, printers, etc.), certified to comply with Class B
limits, can be attached to this computer. Operation with non-certified
peripherals is likely to result in communications interference.
Your house AC wall receptacle must be a three-pronged type (AC
ground). If not, contact an electrician to install the proper receptacle. If a
multi-connector box is used to connect the computer and peripherals to
AC, the ground must be common to all units.
If necessary, consult your Commodore dealer or an experienced radio-
television technician for additional suggestions. You may find the following
FCC booklet helpful: "How to Identify and Resolve Radio-TV Interference
Problems." The booklet is available from the U.S. Government Printing
Office, Washington, D.C. 20402, stock no. 004-000-00345-4.

1581
Disk Drive
User's Guide

Copyright © 1987 by Commodore Electronics Limited
All rights reserved
This manual contains copyrighted and proprietary information. No
part of this publication may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, electronic, me
chanical, photocopying, recording or otherwise, without the prior
written permissibn of Commodore Electronics Limited.
COMMODORE 64 is a registered trademark of Commodore Electronics Limited
COMMODORE 128, Plus 4, and VIC 20 are trademarks of Commodore Electronics Limited

CONTENTS
INTRODUCTION 1
HOW THIS GUIDE IS ORGANIZED 1
PART ONE: BASIC OPERATING INFORMATION
CHAPTER 1: UNPACKING, SETTING UP AND USING THE 1581 3
step-by-step instructions 3
troubleshooting guide 5
tips for maintenance and care 7
inserting a diskette 8
using pre-programmed (software) diskettes 8
how to prepare a new diskette 10
diskette directory 11
selective directories 12
printing a directory 13
pattern matching. 13
splat files 14
CHAPTER 2: BASIC 2.0 COMMANDS 15
error checking 16
BASIC hints 17
save 17
save with replace 18
verify 19
scratch 20
more about scratch. 21
rename 22
renaming and scratching troublesome files.... 23
copy 24
validate 25
initialize 26
CHAPTER 3: BASIC 7.0 COMMANDS 27
error checking 27
save 27
save with replace 28
verify '. 29
copy 29
concat 30

scratch 30
more about scratch 31
rename 32
renaming and scratching troublesome files 33
collect 34
dclear 35
| PART TWO: ADVANCED OPERATION AND PROGRAMMING |
CHAPTER 4: SEQUENTIAL DATA FILES 37
opening a file 38
closing a file 43
reading file data: using input# 44
more about input# 45
numeric data storage on diskette 47
reading file data: using get# 48
demonstration of sequential files 51
CHAPTER 5: RELATIVE DATA FILES 53
files, records, and fields 53
file limits 54
creating a relative file 54
using relative files: record# command 56
completing relative file creation 58
expanding a relative file 60
writing relative file data 60
designing a relative record 60
writing the record 61
reading a relative record 64
the value of index files 67
CHAPTER 6: DIRECT ACCESS COMMANDS 69
opening a data channel for direct access 69
block-read 70
block-write 71
the original block-read and block-write commands 72
the buffer pointer 74
allocating blocks 75
freeing blocks 76
partitions and sub-directories 77
using random files 79

CHAPTER 7: INTERNAL DISK COMMANDS 81
memory-read. 82
memory-write 84
memory-execute 85
block-execute 85
user commands 86
utility loader 87
auto boot loader 88
CHAPTER 8: MACHINE LANGUAGE PROGRAMS 89
disk-related kernal subroutines 89
CHAPTER 9: BURST COMMANDS 91
cmdl-read 91
cmd2-write 92
cmd3-inquire disk 92
cmd4-format 93
cmd6-query disk format 94
cmd7-inquire status 94
cmd8-dump track cache buffer 95
chgutl utility 95
fastload utility 96
status byte breakdown 96
burst transfer protocol 97
explanation of procedures 98
CHAPTER 10:1581 INTERNAL OPERATION 101
logical versus physical disk format 101
track cache buffer 101
controller job queue 102
vectored jump table 108
APPENDICES:
A: changing the device number Ill
B: dos error messages 113
C: dos diskette format 119
D: disk command quick reference chart 123
E: specifications of the 1581 disk drive 125
F: serial interface information 127
USER'S MANUAL STATEMENT inside back cover

INTRODUCTION
The Commodore 1581 is a versatile 3.5" disk drive that can be
used with a variety of computers, including the COMMODORE 128™,
the COMMODORE 64®, the Plus 4™, COMMODORE 16™, and VIC 20.™
Also, in addition to the convenience of 3.5" disks, the 1581 offers
the following features:
• Standard and fast serial data transfer rates—The 1581 auto
matically selects the proper data transfer rate (fast or slow) to
match the operating modes available on the Commodore 128
computer.
• Double-sided, double-density MFM data recording—Provides
more than 800K formatted storage capacity per disk (400K +
per side).
• Special high-speed burst commands—These commands, used
for machine language programs, transfer data several times
faster than the standard or fast serial rates.
HOW THIS GUIDE IS ORGANIZED
This guide is divided into two main parts and seven appendices,
as described below:
PART ONE: BASIC OPERATING INFORMATION—includes all the
information needed by novices and advanced users to set up and
begin using the 1581 disk drive. PART ONE is subdivided into
three chapters:
• Chapter 1, Unpacking, Setting Up and Using the 1581, tells you
how to use disk software programs that you buy. These pre
written programs help you perform a variety of activities in
fields such as business, education, finance, science, and recrea
tion. If you're interested only in loading and running pre
packaged disk programs, you need read no further than this
chapter. If you are also interested in saving, loading, and run
ning your own programs, you will want to read the remainder
of the guide.
• Chapter 2, Basic 2.0 Commands, describes the use of the
BASIC 2.0 disk commands with the Commodore 64 and Com
modore 128 computers.
• Chapter 3, Basic 7.0 Commands, describes the use of the
BASIC 7.0 disk commands with the Commodore 128.

PART TWO: ADVANCED OPERATION AND PROGRAMMING—is
primarily intended for users familiar with computer program
ming. PART TWO is subdivided into six chapters:
• Chapter 4, Sequential Data Files, discusses the concept of data
files, defines sequential data files, and describes how sequen
tial data files are created and used on disk.
• Chapter 5, Relative Data Files, defines the differences between
sequential and relative data files, and describes how relative
data files are created and used on disk.
• Chapter 6, Direct Access Commands, describes direct access
disk commands as a tool for advanced users and illustrates
their use.
• Chapter 7, Internal Disk Commands, centers on internal disk
commands. Before using these advanced commands, you
should know how to program a 6502 chip in machine lan
guage.
• Chapter 8, Machine Language Programs, provides a list of
disk-related kernal ROM subroutines and gives a practical ex
ample of their use in a program.
• Chapter 9, Burst Commands, gives information on high-speed
burst commands.
• Chapter 10,1581 Internal Operations, describes how the 1581
operates internally.
APPENDICES ATHROUGH F—provide various reference information;
for example, Appendix A tells you how to set the device number
through use of two switches on the back of the drive.

PART ONE
BASIC OPERATING INFORMATION
CHAPTER 1
HOW TO UNPACK, SET UP AND
BEGIN USING THE 1581
STEP-BY-STEP INSTRUCTIONS
1. Inspect the shipping carton for damage.
If you find any damage to the shipping carton and suspect that the
disk drive may have been affected, contact your dealer.
2. Check the contents of the shipping carton.
Packed with the 1581 and this book, you should find the following:
electrical power supply, interface cable, Test/Demo diskette, and a
warranty card to be filled out and returned to Commodore.
3. Remove the shipping spacer from the disk drive.
The spacer is there to protect the inside of the drive during
shipping. To remove it, push the button on the front of the drive
(see Figure 1) and pull out the spacer.
Figure 1. Front of 1581 Disk Drive
H
■ commodore 1581 ^H
1 FLOPPY DISK DRIVE ■
V
THE PRODUCT DOES NOT NECESSARILY RESEMBLE THE PICTURE INSIDE THE USER'S MANUAL
3

4. Connect the power cord.
Check the ON/OFF switch on the back of the drive (see Figure 2)
and make sure it's OFF. Connect the power supply where indicated
in Figure 2. Plug the other end into an electrical outlet. Don't turn
the power on yet.
Figure 2. Connection of Power Cord and Interface Cables to 1581
BACK OF
C128
SERIAL PORT
CONNECTOR
ON
C128
POWER CORD
SOCKET
BACK OF 1581
SERIAL PORT
CONNECTORS
FOR
INTERFACE
CABLES
DIP SWITCHES
FOR CHANGING
DEVICE
NUMBER
ON/OFF
SWITCH
POWER
OUTLET

5. Connect the interface cable.
Make sure your computer and any other peripherals are OFF. Plug
either end of the interface cable into either serial port on the back
of the drive (see Figure 2). Plug the other end of the cable into the
back of the computer. If you have another peripheral (printer or
extra drive), plug its interface cable into the remaining serial port
on the drive.
6. Turn ON the power.
With everything hooked up and the drive empty, you can turn on
the power to the peripherals in any order, but turn on the power to
the computer lasfe When everything is on, the drive goes through a
self test. If all is well, the green light will flash once and the red
power-on light will glow continuously. If the red light continues to
flash, there may be a problem. In that case, refer to the Trouble
shooting Guide.
TROUBLESHOOTING GUIDE
Problem
Red power-on
indicator not
lit
Red light flashing e
Possible Cause
Power not ON
Power cable not
plugged in
Power off to wall outlet
Drive failing its self test
Solution
Make sure ON/OFF
switch is ON
Check both ends of
power cable to be sure
they are fully inserted
Replace fuse or reset
circuit breaker in house
Turn the system off for a
moment then try again.
If the light still flashes,
turn the drive off and on
again with the interface
cable disconnected. If
the problem persists,
contact your dealer. If
unplugging the
interface cable made a
difference, make sure
the cable is properly
connected If that
doesn't work, the
problem is probably in
the cable itself or
somewhere else in the
system

TROUBLESHOOTING GUIDE (Cont.)
Programs won't load
and the computer says
"DEVICE NOT PRESENT
ERROR"
Programs won't load,
but the computer and
disk drive give no error
message
Interface cable not well
connected or drive not
ON
Switches on back of
drive may not be set for
correct device number
Another pan of the
system may be
interfering
Be sure the cable is
properly connected and
the drive is ON
Check Appendix A for
correct setting to match
LOAD command
Unplug all other
^machines on the
computer. If that cures
it, plug them in one at a
time. The one just
added when the trouble
repeats is most likely
the problem
Trying to load a
machine language
program into BASIC
space will cause this
problem
Programs won't load
and red light flashes
Disk error Check the error channel
to determine the error,
then follow the advice
in Appendix B to correct
it. The error channel is
explained in Chapters 2
and3
o
(Be sure to spell program names correctly and include the exact punctuation when
loading the programs)
Your programs load OK,
but commercial
programs and those
from other 1581s don't
Either the diskette is
faulty, or your disk drive
is misaligned
Try another copy of the
program. If several
programs from several
sources fail to load, have
your dealer*align your
disk drive
Your programs that
used to load, won't
anymore, but programs
saved on newly-
formatted diskettes will
Older diskettes have
been damaged
The disk drive has gone
out of alignment
Recopy from backups
Have your dealer align
your disk drive

TIPS FOR MAINTENANCE AND CARE
1. Keep the drive well ventilated.
A couple of inches of space to allow air circulation on all sides will
prevent heat from building up inside the drive.
2. The 1581 should be cleaned once a year in normal use.
Several items are likely to need attention: the two read/write heads
may need cleaning (with 91% isopropyl alcohol on a cotton swab).
Tjfcte rails along which the head moves may need lubrication (with a
special molybdenum lubricant, not oil), and the write protect sen
sor may need to be dusted. Since these chores require special
materials or parts, it is best to leave the work to an authorized
Commodore service center. If you want to do the work yourself,
ask your dealer for the appropriate materials. IMPORTANT: Home
repair of the 1581 will void your warranty.
3. Use good quality diskettes.
Badly-made diskettes can cause increased wear on the drive's read/
write head. If you're using a diskette that is unusually noisy, it could
be causing added wear and should be replaced.
4. Keep diskettes (and disk drive) away from magnets.
That includes the electromagnets in telephones, televisions, desk
lamps, and calculator cords. Keep smoke, moisture, dust, and food
off the diskettes.
5. Remove a diskette before turning the drive off.
If you don't, you might lose part or all the data on the diskette.
6. Don't remove a diskette from the drive while the green light is
glowing and the drive motor is turning.
If you remove the diskette then, you might lose the information
currently being written to the diskette.

INSERTING A DISKETTE
Grasp the diskette by the side opposite the metal shutter. Hold it
with the label up and the write-protect notch down and to the left (See
Figure 3). Insert the diskette by pushing it straight into the drive with
the access slot going in first and the label last. Be sure the diskette goes
in until it drops into place; you shouldn't have to force it.
WRITE PROTECT TAB — g[
V
INSERTTHIS
EDGE FIRST
. CENTER HUB
SHUTTER
Figure 3. Inserting a Diskette
When the write/protect notch is open, the contents of the diskette
cannot be altered or added to. That prevents accidental erasing of
information you want to preserve.
Blank diskettes may not have a label on them when you purchase
them.
USING PRE-PROGRAMMED (SOFTWARE) DISKETTES
Your software user's guide should list the procedure for loading
the program into your computer. Nevertheless, we've included the
following procedure as a general guide. You'll also use this procedure
to load programs or files from your own diskettes. For purposes of
demonstration, use the Test/Demo diskette included with the disk
drive.

1. Turn on system.
2. Insert diskette.
3. If you are using a VIC 20, Commodore 64, or a Commodore 128
computer in C64 mode, type: LOAD "HOW TO USE",8
If you are using a Plus/4 or Commodore 128 in C128 mode, type:
DLOAD "HOW TO USE"
4. Press the RETURN key.
5. The following will then appear on the screen:
SEARCHING FOR 0:HOW TO USE
LOADING
READY
I
6. Type: RUN
7. Press the RETURN key.
To load a different program or file, simply substitute its name in
place of HOW TO USE inside the quotation marks.
-NOTE
The HOW TO USE program is the key to the Test/
Demo diskette. When you LOAD and RUN it, it provides
instructions for using the rest of the programs on the dis
kette. To find out what programs are on your Test/Demo
diskette, refer to the section entitled "DIRECTORIES" later
in this chapter.
If a program doesn't load or run properly using the above meth
od, it may be that it is a machine language program. But unless you'll
be doing advanced programming, you need not know anything about
machine language. A program's user's guide should tell you if it is
written in machine language. If it is, or if you are having trouble
loading a particular program, simply add a ;1 (comma and number 1)
at the end of the command.

NOTE
Throughout this manual, when the format for a com
mand is giv^n, it will follow a particular style. Anything that
is capitalized must be typed in exactly as it is shown (these
commands are listed in capital letters for style purposes,
DO NOT use the SHIFT key when entering these com
mands). Anything in lower case is more or less a definition
of what belongs there. Anything in brackets is optional.
For instance, in the format for the HEADER command
given on the following page, the word HEADER, the capital I
in lid, the capital D in Ddrive#, and the capital U in Ude*-
vice# must all be typed in as is (Ddrive# and Udevice# are
optional).
On the other hand, diskette name tells you that you
must enter a name for the diskette, but it is up to you to
decide what that name will be. Also, the id in lid is left to
your discretion, as is the device# in Udevice#. The drive#
in Ddrive# is always 0 on the 1581, but could be 0 or 1 on a
dual disk drive. Be aware, however, that there are certain
limits placed on what you can use. In each case, those limits
are explained immediately following the format (for in
stance, the diskette name cannot be more than sixteen
characters
and the device# is usually 8).
Also be sure to type in all punctuation exactly where
and how it is shown in the format.
Finally, press the RETURN key at the end of each
command.
HOW TO PREPARE A NEW DISKETTE
A diskette needs a pattern of circular magnetic tracks in order for
the drive's read/write head to find things on it. This pattern is not on
your diskettes when you buy them, but you can use the HEADER
command or the NEW command to add it to a diskette. That is known
as formatting the disk. This is the command to use with the C128 in
C128 mode or Plus/4:
HEADER "diskette name",Iid,Ddrive#[,Udevice#]
Where:
"diskette name" is any desired name for the diskette, up to 16 charac-
10

ters long (including spaces), "id" can be any two characters as long as
they don't form a BASIC keyword (such as IF or ON) either on their
own or with the capital I before them. "drive#" is 0 . "device#" is 8,
unless you have changed it as per instructions in Appendix A (the 1581
assumes 8 even if you don't type it in).
The command for the C64, VIC 20, or C128 in C64 mode is this:
OPEN 15,device#,15,"NEWdrive#:diskette name,id"
CLOSE 15
The device#, drive#, diskette name, and id are the same as
described above.
The OPEN command is explained in the next chapter. For now,
just copy it as is.
-NOTE
FOR ADVANCED USERS
If you want to use variables for the diskette name or id, the
format is as follows:
C128, Plus/4: HEADER (A$),I(B$),D0
C64: OPEN 15,8,15:PRINT#15,"N0:" +A$ + "," + B$:
CLOSE15
Where:
A$ contains the diskette name (16 character limit)
B$ contains the id (2 characters long)
After you format a particular diskette, you. can reformat it at any
time. You can change its name and erase its files faster by omitting the
id number in the HEADER command.
DISKETTE DIRECTORY
A directory is a list of the files on a diskette. To view the directory
on the C128 or Plus/4, type the word DIRECTORY on a blank line and
press the RETURN key or simply press the F3 key on the C128. That
doesn't erase anything in memory, so you can call up a directory
11