titus-larsen-titus-1981-apple-interfacing

e converter will not burn out, since it can only accept an 8-bit
le, which corresponds to an output of + 10 volts. The "15" input
15 volts will cause an ILLEGAL QUANTITY ERROR, since we
trying to transfer the value 382 to an 8-bit device. It just can't
done with eight bits.
t this point, you should be able to write a program that will alyou
to enter an upper voltage and a lower voltage, and to have
:tite Apple generate a triangular wave between them. Use your best
togramming skills.
e used the following program:
INPUT "UPPER VOLTAGE"; H
IF H = 0 THEN 40
PRINT "VOLTAGE OUT OF BOUNDS": GOTO 10
INPUT "LOWER VOLTAGE"; L
IF L = 0
PRINT "VOLTAGE OUT OF BOUNDS": GOTO 40
IF H > L THEN 90
PRINT "UPPER V MUST BE HIGHER THAN LOWER V": GOTO 10
H = H * 25.5: L = L * 25.5
FOR V = l TO H
POKE 49318, V
NEXT V
FOR V = H - 1 TO L + 1 STEP - 1
POKE 49318, V
NEXT V
GOTO 100
";n your program and test it. You should be able to make the meter
edle "swing" between the upper and lower voltages. You may use
time delay, or delays, if you wish to slow the meter movement so
t
can easily watch it.
experiment clearly shows you how a simple DI A converter
y be interfaced to your computer. The NE5018 used internal
tches, and much of the analog circuitry has been placed on the
nverter chip. D/ A converters find use in applications that require
e computer to control voltage-dependent devices, such as servo
tors, amplifiers, etc.
ou will not use the NE5018 D/ A converter again, so you may
it from your breadboard. The SN7 402 NOR gate chip should
retained, but the SN7 404 inverter may be removed. Power may
turned off. Carefully remove the connections to the + 12- and
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