A

15

A

12

Result: 15 – 3

 

 

 

 

that is, A – x

 

 

 

 

 

 

 

 

 

T

t

T

t

 

 

 

 

 

 

Z

z

Z

z

 

 

 

 

 

 

Y

y

Y

y

 

 

 

 

 

 

X

3

A X

3

 

 

 

 

 

 

￿Recall Arithmetic

Recall arithmetic uses , , , or to do arithmetic in the X–register using a recalled number and to leave the result in the display. Only the X–register is affected. The value in the variable remains the same and the result replaces the value in the x-register.

New x = Previous x {+, –, ⋅, ⎟} Variable

For example, suppose you want to divide the number in the X–register (3, displayed) by the value in A(12). Press A. Now x = 0.25, while 12 is still in A. Recall arithmetic saves memory in programs: using A (one instruction) uses half as much memory as A, (two instructions).

A

12

 

A

12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

T

t

 

T

t

 

 

 

 

 

 

 

Z

z

 

Z

z

 

 

 

 

 

 

 

Y

y

 

Y

y

Result: 3 ⎟ 12

 

 

 

 

 

that is, x ⎟ 12

X

3

A

X

0.25