Some Notes on Speeding Up Certain Loops by Software, Firmware, and Hardware Means

Some ways of speeding up certain loops by software, firmware, and hardware means are discussed in this note. The importance of the inner loop calculation is emphasized and a simple, though as yet unused, programming technique is presented whereby the inner loop time may be reduced by approximately 20 percent. The general problem of a program with many loops is then considered and a method is indicated for obtaining the maximum speedup by means of the technique described earlier. Turning to firmware, it is shown how, by altering the normal algorithm used for the inner loop calculation, a very substantial speedup can be achieved with the use of microprogramming (above and beyond the savings in instruction decoding time). Finally, a means is considered whereby a computer can alter its own hardware, so as to achieve a speedup of several orders for loops in which the resolution of decision tables accounts for a significant portion of the iteration time.