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