Table of Contents
Advertisement
Software Usage and Examples
ELECTRONIC DISC SOFTW ARE
The HP 82718A provides 32 or 64 kbytes of additional memory for your use. This memory does not
expand the main memory of the HP-75; that is, you cannot create and run programs that are larger than
the 14,000 bytes available in the HP-75 (22,000 bytes with the 82700A Memory Module). The extra
memory behaves like a fast, reliable mass storage device-you can copy files to and from it, catalog it, and
purge and rename files on it, just as you would on a cassette or disc drive. You can also create text and
data files as large as the available memory in the HP 82 718A. Operations are fast because memory can
be accessed quicker than a mechanical device, and reliable because there are no moving parts. Because
this RAM behaves like mass storage, the extra memory is called an
electronic disc.
The electronic disc software lets you create, access, and modify text and data files on the electronic disc,
establish a hierarchical file structure, and copy files into and out of the electronic disc. This software is
designed to be a logical extension to the HP-75 operating system. Everything you understand about
random and serial access of text and data files can be easily extended to include the electronic disc, and
HP-75 commands that apply to mass storage devices will behave the same way when used with the
electronic disc.
Adapting Existing Programs to Use the Electronic Disc
The electronic disc is identified by the device code
>::t'1Et'1
(for
extended
or
external memory).
You can use
this code in all the places where you would normally use an HP-IL device code for a mass storage device.
For example, to copy file
ABC
from HP-7 5 main memory to a cassette drive named
t'11,
you would type:
COP'-!' "ABC" TO ":t'11"
[RTN]
To copy the same file to the electronic disc, type:
COP'r' "ABC' TO ": ::-::t'1H1"
[RTN]
Commands that are extended to use the
>=:t' 1 Et' 1
device code for the electronic disc are
A::;::::I
Gt·~
#, CAT,
COP'-!', PUHGE,
and
PEt·~At'1E.
Programs that interact with mass storage or with text and data files can usually be modified to use the
electronic disc with only trivial changes. If a program is accessing files in main memory or on mass
storage, all that you need to do is add or change the device code. One way to do that is to change all the
file references so they append the device code as a string variable. Then set the string variable to reflect
the use of main memory, mass storage, or the electronic disc:
1O~]
COP'r' "ABC: t'11" TO G$
20(1 PUPGE "DEF: t'11
II
becomes
49
Advertisement
Table of Contents
