gray@pender.ee.upenn.edu (H.J. Gray) (08/28/90)
I purchased a Turbow board equipped with an 80287 from Suitable Solutions just before they closed. It works fine (in the Rainbow) except for one problem: I wrote a short program to test out some of the aritmetic operations (+, *, /, power, exp, log, -). The user selects the operation to be tested, the number of times the operation is carried out, whether or not data is to be displayed, and the size of the error that is allowed. The number of trials I have used vary anywhere from 10 to 10000. The arguments (both mantissa and exponent) are constructed using the pseudo random number generating functions in the compiler run-time libraries. If the program has been compiled using Microsoft C version 5.1, intermittent errors occur in multiply and power but not in the others tested. These errors occur at the rate of anywhere from 10% to 90% of the trials. No errors occur when the program is run using an 8087 board from Suitable Solutions in the Rainbow or the 80287 is locked out using SET NO87= 80287 disabled in the environment. If the test program is compiled using Desmet C version 2.4 with the cstdio87.s library, no errors occur when using Turbow or the 8087 board. My guess is that there is a timing problem; I should use a faster 80287 or a slower 80287 clock crystal. Anybody have any other opinions? Josh