- What does
dec a
do?
Decreases the accumulator
Copies a
to c
Stores the a
register.
Dec a
stands for DECrement the Accumulator,
which is the a
register.
- What does
call _clrLCD
do?
Defines an alias
Clears the screen
Runs the program call
_clrLCD
is a subroutine that clears the Liquid Crystal
Display of the calculator.
- %00001111 is equal to what?
15
24
4
This is binary for 15.
- What must come to the left of each instruction in your code?
The letter A
A call
White Space
Most assemblers need to see
a space or a Tab in the left margin in order to recognize the line as having
an instruction. Otherwise, the assembler thinks it's an Assembler Directive
or a label.
- What is the Two's Compliment also known as?
Address Referencing
Negative Numbers
An Instruction
Two's Compliment is just another term for
representing Negative Numbers to the calculator.
Or arg1
sets bits in a
(the accumulator) if they are...
Set in either a
or arg1.
Set in a
or arg1 but not both.
Set in both a
and arg1, not in just one of the two.
The Logical Operator or
will set
the bits if they are set at all in either a
or arg1.
_VPuts
is used when?
Checking for a key being pressed.
Plotting a pixel on the screen.
Printing text to the screen.
_VPuts
prints menu size (variable width)
text on the screen.
- If you wanted to rotate the accumulator to the left you would perform the following.
rlca
rra
rlc h
Rlca
rotates the accumulator
to the left with bit 7 moved to the Carry Flag's bit position and also stored in
bit 0 of the accumulator.
- What is a Sprite?
A break command used in debugging
A one-byte call
A small image
Sprites are bit images
that are drawn on the screen frequently.
- What does
pop bc
do?
Zeroes bc
Retrieves bc
from the Stack
Copies b
into the c
register
The instruction pop
is used in conjunction with
push
to store and retrieve register pairs with the help of the Stack.