Watch Out For Splat Files; Printing A Directory; Reading A Directory As A File; Another Way To - Commodore 1541 User Manual

The rest of the directory contains one line per program or file, each line supply"
three pieces of information about its subject.
' Q I
RINTING A DIRECTORY
At the left end of each line is the size of that line's file in blocks (or sectors) of 2Si
p
characters . Four blocks are equivalent to IK (1024 characters) of RAM (read/w . To make a permanent copy of a directory , perhaps to fasten to the di kette's outer
· 'd h ntc ·11 d h ·
memory ms.• et e
compu~er.
(paper) envelope. you w1
ne~
to send t e directory to a printer. such as Commodore's
The middle of each directory line contains the name of the file, enclosed in quotati
MPS SOI, 1520
and
1 . 5 26
se rial bus model . To do this , you may need to refer to your
marks . All characters
between the quote marks are part of the name, and must be ind uct°' rinter manual, but briefly the procedure for listing a directory to device 4 is as follows :
when loading or opening that file . et p
The right portion of each directory line is a three character abbreviation for the fil
~ype
of .that entry.' As we will see in later chapters, there
are
many ways to
sto~
mformauon on a diskette, most of which are associated with a distinctive file type.
TYPES OF FILES AV Al LAB LE
Currently used file types include:
PRG = Program files
SEQ = Sequential data files
REL = Relative data files
USR = User (nearly identical to sequential)
DEL
=
Deleted (you may never see one of these .)
(Not~:
Direct Access files , also called Random files, do not automatically appear in
the directory . They are discussed in Chapter 7 .)
LOAD"$0",8
OPEN 4,4 :CMD 4:LIST
PRINT#4:CLOSE 4
Also note that all of the statements that can be combined on one line already have
been. Type them in immediate mode to avoid disturbing the directory .
All other options , such as differing device numbers , and elective directories (see
next section) can also be specified
a~
usual in the Load command .
WARNING: Be sure to include the PRINT# command after every printer
listing . Otherwise, the printer will remain as an unwanted listener on the serial bus,
and may disrupt other work . Also, do not abbreviate PRINT# as ?#. Although it
will look proper when listed out, it will cause a SYNTAX ERROR in use . The
proper abbreviation for PRINT# is pR .
".1-fter all the directory entries have listed, the directory finishes with a messagi
showing how many blocks of the diskette
are
still available for use . This number can van
~------------------------------_J
from 664 on a new diskette to 0 on one that is already completely full. .
WATCH OUT FOR SPLAT FILES!
READING A DIRECTORY AS A FILE
One indicator you may occasionally notice on a directory line, after you begin savi nj
I~
you w.ould like to read a directory from within a program, you may do so. In Basic
programs and files, is an asterisk appearing just before the file type of a file that is I
3
.s.
simply include the DIRECTORY command in your Basic program . In Basic 2,
blocks long . This indicates the file was not properly closed after it was created, and thall however, and optionally in the others, you will have to Open the directory as though it
should not be relied upon . These "splat" files (as they are called in England) wil were a data file and read it character by character. See the discussion of Get# in Chapter 5
normally need to be erased from the diskette and rewritten. However, do not u e tll for more information .
Scratch command to get rid of them . They can only be safely erased by the Validate all'
Collect commands . One of these should normally be used whenever a splat file is noticei ANOTHER WAY TO BE SELECTIVE
on a diskette . (All these commands are described in the next chapter.) . .
There are two exceptions to the above warning: one is that Validate and ColleC Before d1scu sing the pattern-matching options available for use in several disk
cannot be used on some diskettes that include direct access (random) files, and the othen
c~mmands,
let's cover one more that is only usable in a directory . Several different types
that if the information in the
splat file was crucial and can't be replaced there is a way
1 1
°
files can coexist peacefully on the same diskette . By altering our directory load
' ~mmad · .
rescue whatever part of the file was properly written . (This option is also described in
1
11 . n • we can create a directory from the files of a single selected type . Thus, we
next chapter) .
~~~ht
request a list of all sequential data files (see Chapter 5), one of all the relative data
(see Chapter 6) , or one of only program files . To do this , imply add to the end of
Your sele t' d' .
t c 1ve 1rectory request the equals sign (
=)
followed by the first letter of the file
Ype you want in your directory . For example , the Basic 2 command:
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