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appropriate, no further switch movements will affect
the condition of any of the lights until the next shift
to the left has occurred.
switches time to stop bouncing and stay closed as the
processor in this machine is quite fast enough to see
the slight bouncing of the switch contact when it
initially closes.
By waiting for the next data shift before recognizing
any more switch changes, we are prevented from falsely
interpreting a bouncing contact as a switch which was
repeatedly opened and closed.
be either to turn out all the lights in the shifting
bit pattern by moving a switch when the bits are passing
directly over it, or alternately to turn on all the
bits in the shifting bit pattern by moving a switch when
a bit which is off is directly over it.
shifting bit pattern is all 0's or all l's, no movement
will be seen in the PROGRAMMED OUTPUT port but by
moving any switch, one of the lights will be changed
so that the motion is again apparent.
Players can compete for the shortest time to go from
all O 's r to all l's, or the other way - from all l's
to all 0's .
rotation speed, the switches can be set for a higher
binary number and the system reset to cause the processor
to go back to memory location 0 and begin execution
of the program again, and a new switch setting will
be read to result in a higher rate of rotation, which
makes it harder to move a switch at the exact instant
the bit desired to be changed is directly above it.
If there-were only a single light on,: : circulating across
the output port, and the player,
it off by moving the switch when the bit was directly
over that switch) was too slow, then the bit will have
shifted away so that it is now over the next switch
to the left, not only will that bit not be turned off,
but the bit behind will be turned on so that now there
are two bits circulating across the register and the
player is further away from achieving all bits turned off.
Knowledge of some of the internal structure of the 8080
processor will be necessary to understand the game pro
gram.
The Intel data book contains complete information
and functional specifications on the internal structure
of the 8080 processor, but only the basic aspects of
the structure need be known to understand the program
operation.
42
This was done to give the
When the game has been mastered at one
IMSAI 8080
General Assembly and
Test Instructions
The object of the game can
Any time the
(in attempting to turn
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