HP HP-65 - Page 33

keeping intermediate results in the stack above those being cal-
culated. To lift information in the stack, you have used ENTER4
and the automatic lift. To drop the stack, you have used the arith-
metic functions. We will now consider the three remaining op-
erations to move information in the stack.
Roll Up Roll Down Exchange
t T t T t T
z z z z z z
y Y y Y y Y
X X X X X >< X
You use these operations to verify (display) the contents of stack
registers other than X and to move information into place for
calculation..
Notice that
m allows you to conveniently see t.
u saves X in the T-Register.
= allows you to look at y without altering t or z.
= , and are functions appearing on the[9],[8],
and keys.
You may notice that and are also available on the B}
and [@ keys when the power is first turned on. The five functions
shown in the window were selected because they are the most
commonly used. Their primary intent is for manual use from the
keyboard, as in this case. They each permit single keystroke op-
eration of functions that otherwise would require two keystrokes.
When the [[§, . . . , @ keys are redefined by a program, the
window functions are still available by two keystrokes.