Factorials !!!!

by J.A. Hart

This program produces the factorial of any number between 2 and 3000. Numbers must be input as four digits ie. 2 is input as 0002 and 3000 as 3000. There is no error checking so reset and re-enter number if incorrect. When running, the number of the factorial to which the computer has calculated is displayed on the top left of the screen and the digit length of that number is shown in the middle of the top line. As it is written for maximum speed and not for efficiency in the use of memory, it requires 48K of RAM starting at 1000H. The 48K is for data storage only as the program is less than 1k long. To avoid using more memory for the program, it alters various subroutines which otherwise would be quadruplicated, therefore, it will not work in ROM. The answer is produced 20 times faster than a similar Basic program.