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         Version 1.2
        For TI-83

For four-band and five-band resistors
 by Vasantha Crabb <_merlin@operamail.com>

========================================================================
    INTRODUCTION
========================================================================
Are you one of those people who can never remember whether green means
five or six, or if no tolerance band is 10% or 20%?  Or maybe you just
can't be bothered learning the code at all.  If you fit either of these
categories, Colurs may be just the program you need.

Colurs lets you enter the colours of the bands on a four-band or five-
band resistor and then determines the nominal resistance and tolerance
for the resistor.  It recognises all possible resistance values between
100 m and 999 G (although I don't believe resistors above about 10 M
are commercially available).  Tolerances all the way from 1% to 20% are
now recognised.

Colurs is e-mail ware!  If you use it, send me a note.

You can download the latest versions of Colurs for CrASH and TI-83
from my website at http://members.xoom.com/_merlin/.

!IMPORTANT! The information in this file is specific to the TI-83
            version of Colurs and may not be correct for the CrASH
            version.

========================================================================
    SYSTEM REQUIREMENTS
========================================================================
Colurs 1.2 for TI-83 will run under AShell, SOS or ZASMLOAD.  Colurs
will not run under Aurora. AShell 1.0 and SOS 2.0 are available from
ticalc.org. ZASMLOAD is included with Logic Analyser.  The actual
program variable takes up 974 bytes of memory.  You'll need about 1 kB
of free memory to run Colurs.  I recommend using SOS, as it has a much
wider range of programs available for it, and will run all AShell
programs.

Colurs has been tested on a TI-83 with ROM version 1.06, 1.07 and 1.10
using AShell 1.0, SOS 2.0 and ZASMLOAD.  Although I don't see any
reasons why Colurs shouldn't be compatible with other ROM versions, if
you do experience any problems, please notify me.

========================================================================
    USING COLURS
========================================================================
Download the file "ZCOLOURS.83P" to your calculator.  If you don't have
AShell or SOS installed, download the file "LOADER.83G" to your
calculator. If you get a Duplicate Name error, just choose Overwrite.

If you're using AShell, choose ZCOLOURS from the program list to run
Colurs.  If you're using SOS, choose Colurs 1.2.  To run Colurs using
ZASMLOAD, execute the command prgmCOLOURS from the home screen.  You
will then see the Colurs screen with the program title at the top, a
resistor on the right, a list of colours and a prompt directly below the
title.

Entering the colours for the bands is easy.  You simply use the up and
down arrow keys to select the colour of the band you are being asked for
and then press enter to move to the next band.  The cursor will not move
to a colour which is invalid for the band being entered.

When you have selected the colours of all the bands, Colurs will
display the nominal resistance value and wait for you to press a key
before exiting.

For a four-band resistor, you enter none when prompted for the colour of
the multiplier band.  Note that if you select gold or silver for the
third digit/multiplier band, Colurs automatically determines that you
are entering a four-band code and doesn't prompt you for the multiplier
band.

You can exit from Colurs at any time by pressing 2nd-QUIT.  You can
safely turn the calculator off from inside Colurs by pressing 2nd-OFF.
Colurs supports APD, so if you leave the calculator turned on for an
extended period of time while Colurs is running, the batteries will not
be drained excessively.

========================================================================
    WHY WAS COLURS WRITTEN?
========================================================================
Colurs is my first Z80 assembly language program.  I wrote it partly
because it's a relatively simple problem, and partly to address some of
the short-comings in the other resistor colour coding programs which are
available for the TI-82.  None of them support both the four- and five-
band codes, the use of gold and silver as multipliers or tolerances
other than 5% and 10%.  When they saw it, my friends insisted I write a
TI-83 port so they could use it, too.

========================================================================
    CREDITS
========================================================================
Without Jimmy Mrdels's Ash School, this program would have taken ten
times as long to write.  Also, the port, RAM and ROM documentation
provided with Ash has been invaluable.  When porting to the TI-83, the
information supplied by Texas Instruments was the only reference I
needed.

========================================================================
    DISCLAIMER AND COPYRIGHT
========================================================================
Colurs is provided "as is".  Although I have taken measures to ensure
it's reliability and safety, I cannot guarantee that no problems remain.
I accept no responsibility for any damage which Colurs may cause,
directly or indirectly, to your calculator, your data or your motivation
to learn the resistor colour code.

Colurs is Copyright (c) 2000 Vasantha Crabb.  You may distribute
unmodified copies of the zip archive between computers, or unmodified
copies of the program between calculators.  You may use the source code
in your own projects, as long as it constitutes no more than fifty
percent of the total code and I am acknowledged in the credits.  You
may not distribute modified copies of the program, the documentation
or the source code without my express permission.

========================================================================
    FUTURE PLANS
========================================================================
Add a resistance to colour code function.

Port to Ion.

========================================================================
    VERSION HISTORY
========================================================================
1.2             Added support for high-accuracy resistors.  Smaller
7 June 2000     code size.  OS-82 support discontinued.

1.1             TI-83 port released.  Ash version discontinued.
27 August 1999

1.1             Minor update.  Slightly different output format, smaller
18 June 1999    code size, Ash and CrASH versions released.

1.0             Initial release.  Support for four-band and five-band
14 April 1999   resistors with values between 100m and 999G and
                tolerances between 1% and 20%.  OS-82 Version only.
