Processor Technology Sol-PC, Руководство пользователя

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PROCESSOR TECHNOLOGY CORPORATION
Sol OPERATING PROCEDURES SECTION VII
VII-3
The command mode allows the introduction of the second level
of software. This level includes higher-level language programs such
as BASIC/5 or FOCAL in which complex application programs may be more
easily written. These are called higher level languages because they
permit the user to write programs in a form much closer to human
languages such as English. However, programs written in these
languages must be translated into the more basic machine language
before they can be run. Besides higher level languages, this second
level of software includes programs such as the TREK 80 and GAMEPAC
video games and the ALS-8 program (a software package used for
developing programs), all of which are offered by Processor
Technology Corporation. Through the facilities of the command mode,
these second level programs are transferred (loaded) into memory from
cassette tape or other storage media, and then "executed" (used).
These programs may also exist in ROM or EPROM (erasable programmable
ROM) memory which is plugged into the computer to make them instantly
available like the SOLOS program. All first and second level
programs are stored in the computer as binary object code.
Let us illustrate the concept of the second level of programs
with an example, BASIC/5. Using the "XEQ" command available in the
SOLOS command mode, we load the BASIC/5 program into the computer's
memory from cassette tape. With this command BASIC/5 is ready for
use as soon as the tape has stopped moving. The control of the
computer is now taken over by the BASIC/5 program now in memory, and
SOLOS is no longer in command. All the features of BASIC/5 language
are now available to us, with a new set of commands and rules. Since
the CPU of the computer only understands the machine language of the
first level of software, the BASIC/5 program must translate the
commands and data we enter to this lower level. BASIC/5 does this as
we go. While we are using BASIC/5, we still have access to some of
the commands and features of SOLOS, although they may have a modified
form while we are in BASIC/5. We will load and use BASIC/5 later in
this section.
The third level of software consists of programs written
using the higher order languages of the second level programs. A
program written in BASIC/5 is on this third level. This program only
makes sense to the computer while the computer has BASIC/5 in memory
and control has been transferred to the BASIC/5 program. Third level
programs written in any high level language are often called
"applications programs" since they are usually written in order to
fit a specific application need.
The ALS-8 Program Development System is another second level
program. A program to be developed within ALS-8 would then be a
third-level application program. The ALS-8 also includes an
Assembler which takes a program written on the third level in
"assembly" language, and translates it to object code which the
computer can run. The object code version then resides in memory and
can be run in another operation. For a further discussion, of types
of software see the article "Your Personal Genie" in Appendix VIII of
this manual.