Radio Shack TRS-80 Model II Reference Manual page 8

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VERSION 2.0 UPDATE
"Minimum System"
This is a diskette which cannot be used to start
TRSDOS,
but may be used after the
system is fully initialized. This diskette contains the minimum amount of system
files required for
TRSDOS
operation after initialization.
You may want to create a minimum system diskette for use in special applications
where space in drive 0 is at a premium. You may use
PURGE
or
XFERSYS
to create a
minimum system.
Why and How of Minimum System Diskettes
If you don't have a Disk Expansion Unit, but still need extra disk space for storage
oflarge data or program files, you may ~eed to create minimum system diskettes
for use. This kind of diskette has the minimum operating system programs on it for
processing, but may not be used for resetting or starting up. These diskettes may
only be used in drive 0 after you have reset or started using a full system diskette.
The minimum system diskette will contain the following system programs:
SYSTEM/SYS
SYSTEMnn (nn
=
32
for
32K
machines,
64
for
64K
machines)
Note: If you do not plan to use
DO, HOST, SPOOL, DEBUG,
or serial
I/O
during the
execution of your application, you will not need
SYSTEM 64
or
SYSTEM 32
on your
minimum system diskette.
The technique for using a minimum system diskette is as follows:
1. Initialize using your working master (which must be a full system diskette).
2. Remove this diskette from drive 0 and replace with the minimum system
diskette that you have created.
3. Now you may start running your application which should be on the minimum
system diskette.
If your application requires more than one diskette for the storage of files or
programs, then each diskette used (with your one-drive system) should be a
minimum system. Your application should be written such that you only have files
open on the diskette that is currently in drive 0, and that when you need to swap
diskettes to get data (or programs) from another minimum system diskette, that you
close the open files, then do the swap, then open the file(s) that you need from the
other diskette.
You may also use minimum system diskettes in a multi-drive setup, but keep in
mind that you must start or reset with a full system diskette in all cases.
To Create a Minimum System Diskette
There are two ways to create a minimum system disk. The first is to start with a
copy of either your working master or any other full system disk and, from this,
purge off all of the modules except
SYSTEM/SYS
and
SYSTEM64
(or
SYSTEM32).
The
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