[lokedhs]

Single precision is a 15-bit fixed point number in the range between -1 and 1. Apparently in most cases this was enough for moon flights. There was also double and triple precision that were used sometimes.

Of course, in many places in the code you need values outside of this range and the actual number represented is scaled by some factor. However, the CPU has no internal representation of the scale factor (i.e. the exponent bits in a floating point number) so the programmer had to manually manage this.

I can strongly recommend this book, if you're interested in the AGC: http://www.apolloguidancecomputer.com/