The Signetics 2650 - The MESSUI Place

Special offer for EA readers:
Low cost record of
useful 2650 software
Here is some good news for those using small microcomputer
systems based on the Signetics 2650 microprocessor. Electronics
Australia and Philips Electronic Components and Materials, in conjunction
with the 2650 Users' Group, have produced a low cost
175mm 33 1/3rpm record of useful 2650 system software. You can
load the software into your system via any standard cassette interface.
Most small microcomputer systems
based on the Signetics 2650
microprocessor use the monitor/debug
program `PIPBUG", resident in a ROM
(read-only memory), to control
program entry, manipulation and execution.
And compared with many
similar monitor/debug programs
supplied with small microcomputer
systems, PIPBUG is very good. It allows
you to dump programs onto paper tape
or cassette and reload them into
memory, and to run them in controlled
fashion with up to two breakpoints.
However like most small
monitor/debug programs, PIPBUG has
its limitations. After you have used it for
a while, these become fairly apparent.
You soon find yourself hankering for a
faster and more convenient way of
feeding long programs in, examining
them when they have been fed in
moving parts of them around in
memory, checking the accuracy of
dumps, dumping and reloading, and so
on.
As it happens, many of the utility
programs required to do these things
have already been produced, by people
who have been working with small
2650 systems for a while. So there's no
need for newcomers to "reinvent the
wheel".
To help those who are just starting to
get under way with their 2650 system,
we have gathered together a group of
these utility programs which we think
are likely to be of most interest and
value. With the generous support of
Philips Electronic Components and
Materialt, and the co-operation of the
2650 Users Group, we have recorded
the resulting "software package" on a
low cost 175mm 33-1/3rpm disc. This
can be played on any standard record
player, and fed into your 2650 system
by JAMIESON ROWE
80 ELECTRONICS Australia, April, 1978
via a standard cassette interface such as
the one we described in the April 1977
issue (File number 2/CC/19).
The programs in the package include
routines for feeding in programs faster,
listing them more efficiently, moving
them around in memory, searching
them for certain instructions, verifying
dumps, measuring the length of
programs in dumped form, disassembling
them for analysis, dumping them
and reloading at higher speed than
with PIPBUG, and producing dumps
which automatically begin execution
when they are loaded. There are also
two short game programs, for amusement
and system demonstrations.
All of the programs recorded on the
disc have been dumped from a 2650
system using PIPBUG, so that they are
in the Signetics "Absolute Object Format",
and hence suitable for loading
into other systems under PIPBUG control.
The system from which they were
dumped has a total of 4k (4096) bytes of
RAM in addition to the 1k PIPBUG
ROM, with the RAM occupying the
hexadecimal address range 0400-13FF.
Some of the programs currently occupy
memory locations near the top of that
range.
As many small 2650 systems are likely
to have at least this much RAM, most of
the programs should be usable as they
are. However if your system has a
smaller memory, you should still be
able to use many of the programs.
Quite a few of them are either
relocatable without any changes at all,
or require only a few minor changes.
Others are already located down at the
bottom of RAM memory space, and
should be directly usable.
The programs have been recorded
on the disc using the 2-tone "audio
FSK" technique, with binary 1 and
"mark" represented by a tone of
2400Hz, and binary 0 and "space"
represented by 1200Hz. These are the
same tones used in standard microcomputer
cassette interfaces, based on the
so-called "Kansas City Standard"
originated by the American magazine
Byte. Hence you should be able to feed
the programs from the disc into your
system simply by connecting a standard
record player up to your system's
cassette interface, in place of the
cassette tape recorder.
If you experience any trouble
loading them into your system in this
way, it will probably be because your
cassette interface is not set for exactly
the standard frequencies. A judicious
adjustment of the interface may
therefore be required, by trial and
error, until loading takes place correctly.
This will be a simple procedure if
you are using the cassette interface
described in the April 1977 issue, as you
will only need to adjust the 4.7k "clock
adjust" preset pot a little one way or
the other.
As a special offer to EA readers, we
are making the 2650. Software Package
Recording available at the nominal
price of $2.50, or $3.00 posted
anywhere within Australia. However
your remittance should be accompanied
by the order coupon given in
this article, unless you live in a State
where this requirement is illegal — in
which case a letter giving the same information
may be sent instead.
But note that this offer is strictly
limited. Only 1000 discs have been
produced, and when these have gone
the offer must close. So be early if you
don't want to miss out!
As you can see from the photograph,
the 2650 Software Package Recording
comes inside a matching protective
sleeve. On the sleeve is printed brief information
on each of the various
programs on the disc, and their use.
However in order to let you evaluate
their potential value to you in advance,
the remainder of this article gives a
somewhat expanded description. Also
given are program sizes and
relocatability.