Set of subroutines provides the FORTRAN user with protected, permanent, disk storage of data on an IBM 1620 Monitor 11-D system. The program consists of a set of four subroutines and a utility program. It allows block data to be transferred directly between assigned core locations and disk storage

Krejci, H. F.

English

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October 1969	 Brief 69-10618 
. ICY C
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TES
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the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
IBM-1620 Monitor II-D Disk-Storage Subroutines 
.
The problem: 
To provide a FORTRAN user, working with large 
data sets, with relatively fast and random access to 
disk storage. The advantage of disk storage cannot 
be fully realized on a normal IBM-1620 Monitor Il-D 
System because the RECORD and FETCH statements 
provide only temporary disk storage. 
The solution: 
A set of subroutines that provides the FORTRAN 
user with protected, permanent, disk storage of data 
on an IBM-1620 Monitor ll-D System (ref. 1). The 
program, called the Second-Disk System, consists of 
a set of four subroutines and a utility program. It 
allows a block of data, containing any number of 
variables and/or arrays, to be transferred directly 
between assigned core locations and disk storage. 
Data can be stored on a user's own disk pack or on 
protected areas of a system pack. 
How it's done: 
The Second-Disk System requires the exclusive use 
of a second-disk drive and is entirely independent of 
normal Monitor disk operations. It is written for an 
IBM-1311 Disk Drive with a "direct seek" special 
feature that eliminates the waste of time associated 
with the normal return to home and seek from cylinder 
zero. The only restriction imposed by the Second-
Disk System is that both fixed- and floating-point 
word lengths must be even. 
The storage capacity of a disk pack (2,000,000 digits) 
is often large enough to serve many users. For mutual 
use, a physical disk pack is divided into logical disk 
packs called files. Each file is identified by a unique 
file number and is divided into records. The records, 
the basic addressable units available to the FORTRAN 
program, are numbered consecutively from zero. The
system uses the last 1% of disk storage (cylinder 99) 
as a table to store the record lengths and boundaries 
of each existing file. A utility program is used to 
initialize and update this table. 
Before a file can be used, the record length and file 
boundaries must be read from the table and sent to the 
appropriate subroutine; this is called "opening a file." 
Only one file may be open at any time, and data are 
written on or read from the portion of the open file 
indicated by the record number. Regardless of the 
size of the data block or the record number, data are 
not allowed to exceed the boundaries of the open file. 
For additional protection, the utility program may be 
used to place a file in a "read only" state. All files 
except "file zero" are personal files and assigned to 
individual users for their exclusive use. "File zero" 
is a common file available to all users at all times and 
cannot be file-protected. 
The Second-Disk Subroutine Set consists of four 
subroutines, each written to be compatible with 
calling programs of any word lengths (F and K): 
1. Subroutine SDDEF is used to define the Common 
File record length. 
2. Subroutine SDKEY is used to open a file. 
3. Subroutine SDREC is used to write on an open 
file.
4. Subroutine SDFET is used to read an open file. 
The second-disk utility program is used to initialize 
a disk pack, to define a file, to delete a file definition, 
to declare a file "read only," to declare a file "read/ 
write," and to dump the table of file descriptions. 
Reference: 
I. Krejci, H. F.: 1620 Monitor 1I-D Disk Storage Sub-
routines ANL-7324, Argonne National Laboratory, 
April 1967 (available from CFSTI, Springfield, Va. 
22151, at $3.00—microfiche, $0.65). 
This document was prepared under the sponsorship of the Atomic 
Energy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son acting on behalf of the United States Government assumes any
liability resulting from the use of the information contained in this 
document, or warrants that the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
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Note: 
Inquiries concerning this information may be di-
rected to:
Patent status: 
Inquiries regarding commercial use of this informa-
tion may be made to: 
Office of Industrial Cooperation 
Argonne National Laboratory 
9700 South Cass Avenue 
Argonne, Illinois 60439 
Reference: B69-10618
Source: H. F. Krejci 
Applied Mathematics Division
(ARG- 10376)
Mr. George H. Lee, Chief 
Chicago Patent Group 
U.S. Atomic Energy Commission 
Chicago Operations Office 
9800 South Cass Avenue 
Argonne, Illinois 60439 
Brief 69-10618
	 Category 01


IBM-1620 monitor 2-D disk-storage subroutines

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