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MATHCO.TXT
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2006-10-19
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ORIGINALLY PUBLISHED IN LIMA NEWSLETTER JUNE 1991
^^^^^^^ A MATH COPROCESSOR FOR THE 99/4A
^^^^^^^^^^^^^^^^by Charles Good
^^^^^^^^^^^^^^Lima Ohio User Group
A math coprocessor can do mathematics independent of a
computer's main CPU. When using such a coprocessor the
effect is similar to running two programs simultaneously.
The coprocessor does its calculations while the main program
continues to run uninterrupted. The results of the math
coprocessor's calculations can then be fed into the main
program. For examnple, have you ever used MULTIPLAN and
wanted to recalculate one small part of the spreadsheet
instead of waiting and waiting for MULTIPLAN to recalc the
whole thing? Or have you ever been in the middle of an
accounting program, such as one designed to balance your
checkbook, and wanted to do a little quick calculating. In
a BASIC program you can usually press CLEAR. Then from
command mode type PRINT followed by your calculations.
Pressing ENTER gives you your answer and then you can type
CON to continue the program. This is rather cumbersome, and
the program's screen display is disrupted. With an assembly
language program you don't even have this option.
Well, let me introduce you to the TI-7000 math
coprocessor. This inexpensive peripheral attaches to the
99/4A console just above the keyboard. It uses no extra
power and is always available to do independent calculations
which can then be fed into the main running program via the
99/4A's keyscan routine. Permanent or temporary
installation can be done by anyone following the simple
instructions that come with the installation kit, since no
soldering is required. I paid $4.93 for my TI-7000, and
an additional small sum for the installation kit. Every
serious 99/4A user should have one of these.
The Texas Instruments TI-7000 is a credit card sized
solar powered calculator. No battery is ever needed. It
can be permanently mounted to the flat area above the
99/4A's keyboard with super glue, or can be temporarily
attached using double sticky tape. It's nice ruberized keys
give a tactile response when they are pressed, and the LED
display is easy to read. It has + - * / and % keys and
includes one memory. I bought mine at WAL-MART. Output
from the TI-7000 is entered into the 99/4A via the keyboard,
which is of course detected with the 99/4A's keyscan
assembly routine.
How about a battery backed clock/calendar for the
99/4A? CorComp's TRIPLE TECH card is conveniently hidden in
the PE box and provides this function. But you can't get the
thing to automatically time/date stamp your disk files. A
used TRIPLE TECH usually sells for $75. I found an equally
convenient device in the automobile section of WAL-MART for
only $2.95 complete with installation kit. I mounted this
small battery clock/calender next to my math coprocessor.
You can also use the double sticky tape that comes with it
to mount this clock on the dashboard of your car. As with
the TRIPLE TECH card, I can now always get a display of the
current time, month, and day of the month as I sit typing
newsletter articles. Also like the TRIPLE TECH, I can't
time/date stamp my disk files with this device.
.PL 1