Your IBM Computer, May-1984
by Lloyd Borrett
Your Computer, May 1984
Most people in the computing community are able to recall
the names of some of the more successful microcomputer
software products. To many, a spreadsheet program is
VisiCalc, not vice versa. When it comes to microcomputer
database software, dBase II is the name they remember.
Ashton-Tate's dBase II is one of the success stories of
the microcomputing industry. More and more software houses
are realising that in dBase II they have not only a
relational database, but also a fully-fledged computer
language that programmers can use to write application
systems. The market for dBase II compatible products has
become an industry in its own right.
dBase II was developed for use on 8-bit CP/M machines,
and was one of the first programs to be ported to CP/M-86,
MS-DOS and PC-DOS when the 16-bit machines were released.
The program remained functionally identical to the 8-bit
version, and initially made little use of the IBM-PC's
screen and keyboard features. Version 2.4 added some useful
new features and fixed some of the more notable bugs found
in previous versions, but it still did not make use of the
extra power of a 16-bit machine.
Naturally, the competition realised this and lately more
powerful database products have appeared. Some of these
products are dBase II clones, others try to break new
ground. As is often the case with new products, many have
their own limitations. People have been reluctant to abandon
Fortunately, Ashton-Tate does not intend to sit back and
watch its market slip away. The company recently announced
the development of dBase II 2.6. No public release date was
given and it was made clear that certain features of version
2.6 were still tentative.
dBase II version 2.6 will only run on the IBM-PC and
compatible machines; that is, it's exclusively 16-bit. It is
estimated to be only 80 per cent compatible with current
dBase II releases. Some of the features are:
- The ability to have four databases open
- Capacity for up to two million characters per
record, and up to two billion records per database. (How
many years would it take to back up such a database
using floppy disks?)
- Memory variable space is increased to 6000 bytes and
memory names to 256.
- Numeric accuracy is up to 15.9 digits. using the
IEEE Floating Point Format Standard.
- The SET PATH command under PC-DOS 2.0 allows you to
set the path to a particular directory or sub-directory.
- A TIME function to get the time of day.
- The STORE command has been changed to the equal sign
(=), working from right to left as it does in most other
- The new SEEK command will FIND on a substring of an
- Square root, natural log, exponential notation, and
Julian date to calendar date (and back again) functions
are also included.
- There is also a new type of field called a text
field. This field has an associated text file of up to
4000 characters, modifiable with a new streamlined word
These are but some of many notable features announced.
Ashton-Tate is also working on a multi-user version of dBase
II 2.6. (No prizes for picking UNIX as the operating
system.) dBase II is firmly established as the market leader
in the mid-range of database product offerings. If
Ashton-Tate can deliver the features announced, dBase II is
likely to remain on top of the heap.
Diskettes (and all other computer storage media) are
fragile. It's easy to forget that. You can use a diskette
for months with no trouble, but once in a while, just when
you least expect it, just when it's least convenient, a
problem will occur.
However, you will probably be the cause of the majority
of data losses. Many of the DOS commands (ERASE, FORMAT,
COPY), if used carelessly, can destroy your data. It's so
easy to create files that most people don't appreciate the
value of the data until they lose it.
The answer is to make back-up copies. A back-up copy is
the only form of insurance available. Take a look at your
collection of diskettes now. How many hours have you
invested in them? How would you like to have to reproduce
them from scratch?
Unfortunately, past experience shows you're unlikely to
do anything about back-ups until it's too late. Only when
you find yourself in the situation where a file is
permanently lost does this sink in. In the mainframe world
people are employed to make sure the data is backed up. In
the microcomputer world there is only you. The importance of
back-ups can't be overstated. So what do you do?
First, divide your diskettes into work, program and
project categories. The work diskettes should contain no
permanent files. Data on a work diskette is temporary, and
doesn't need to be backed up. Any program files on work
diskettes can be recovered from program diskettes.
When a new program is received, make a copy of the
distribution diskettes. The distribution diskette is then
archived and the installation procedures are carried out on
the copy. When completed, yet another copy is made and
labelled 'Working Copy'. This is the diskette that goes into
use. The other diskette is labelled 'Back-up Copy' and filed
Should a working copy program diskette become corrupted,
you can make a new one from the back-up copy without having
to go through the installation procedures again. If both
copies fail, make sure your hardware is in full working
order before placing a distribution diskette at risk.
The files on project diskettes are related. These need to
be backed up, but not always with the same frequency.
Project diskettes that contain high-priority work, or
current work that is changing often, can be backed up more
often. Project diskettes that change little can be backed up
For a simple back-up, the procedure is to:
- get the back-up diskette from storage
- copy the working diskette onto it with DISKCOPY
- compare the two diskettes with DISKCOMP
- return the back-up diskette to storage.
One diskette is always the back-up copy and the other is
always the working copy. The working copy gets all the use,
all the wear, and is exposed to all the hazards.
A rolling back-up allows the wear and tear to be shared
equally by the diskettes. Each time you make a back-up copy,
you put the copy back into use and the original is stored.
You choose the period between back-ups — be sure to make it
This scheme creates a single level of back-up. You can
expand a rolling backup to have as many levels as you wish.
A typical example for valuable diskettes is to have a
diskette for each day of the week, thus giving four levels
If you think this is overdoing it, then you haven't yet
learned the lesson the hard way. Besides, I'm not finished
yet. Remember earlier when I suggested the distribution
diskettes should be archived?
If the back-up diskettes are kept in the same building
with the computer, they are exposed to any disaster that
destroys the computer itself. Hardware can be replaced
easily, but data cannot. As this is a fairly unlikely
situation, you can perhaps allow a disaster-proof back-up
copy to be a bit out of date.
In other words, you should keep archived diskettes off
the premises, or in a fireproof safe, and regularly take
archival copies of your project diskettes.
Saturday, 15 October 2011