/c. Selects the max value for the demoninator of a fraction. E.g. /c value of 60 for working in seconds?

RND. Rounds the X register value

Hex keys. Keys C1 to C6 ( SIN to 1/x) are the keys to use when entering hex digits A..F. For Hex arithmetic, Sheesh. ↱ BASE 2. (Enter digits), ↱BASE 6 ENTER. (Enter second digits), ↱BASE 6, then finally enter the operation!

Mode key (A4),

But don't forget that EQN (equation mode) has its own key, E1. This enters and leaves EQUATION mode. To enter an equation, hit the EQN key. This enables entry of an equation. If you want to store the result, start the equation with N=, where N is a variable, A..Z. Finish entering the equation with the EQN key again.

The R/S has me scratching my head. What does it stand for? If anything? Register Store perhaps? Seems to take the X register and stuff it into the named variable.

In operation, I find using ENTER more intuitive than XEQ. Having entered an equation, of the

  x=f(x)

variety, I find that the following sequence works to evaluate the LHS

Press EQN, select the one you want from the available ones. Hit ENTER to start prompting for the RHS values. As each is entered (or calculated), use R/S to load it into the equation variable. Continue until all variables have been satisfied. When all the variables are loaded the result will show in the X register.

P 14 - 9 .

Load /c register by loading a number (<4095) into the X register, then ↰ /c

Fgs 0-4 for users to use

Fg 5. Set - Stop program on overflow. Clear. Flash message, then continue, using Nmax.

Fg 6. Set on overflow. No action.

Fg 7. Set. Display fractions. Clear. Display in default disp format

Fg 8. Set. Demoninator is a factor of /c value. Clear. Demoninator <= /c

Fg 9. Set. No reduction of fractions. Clear. Reduce to smallest form