Answers
F8.2 Binary and denary
Data representation · GCSE · OCR J277 1.2.4, AQA 8525 3.3.1, Edexcel 1CP2 2.1.3 · about 15 min
Data representation · GCSE · OCR J277 1.2.4, AQA 8525 3.3.1, Edexcel 1CP2 2.1.3 · about 15 min
Converting 8-bit numbers both ways, and hearing them on the buzzer.
[1 mark]What is 01001101 in denary?
[1 mark]Write 200 as an 8-bit binary number.
[1 mark]What is the largest number 8 bits can hold?
[1 mark]Write 5 as an 8-bit binary number.
[1 mark]What does this program print?
total = 0
value = 1
for bit in reversed("1010"):
if bit == "1":
total = total + value
value = value * 2
print(total)10
1010 is 8 + 2 = 10.
[1 mark]What is the place value of the leftmost bit in an 8-bit binary number?
Write to_binary(n) yourself, without bin, format or int(..., 2), that returns an 8-character string of 1s and 0s. Use it to print the binary of 77, 5 and 200, one per line, and then play the bits of 77: a note of 880 Hz for each 1 and 440 Hz for each 0, each for 0.2 seconds.
# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()
def to_binary(n):
return ""The hint students can ask for: Work down the place values from the largest. If the number is at least the place value, the bit is a 1 and you take that value off; otherwise it is a 0. Then sound a high or low note for each bit in turn.
from bugbot import *
connect()
def to_binary(n):
bits = ""
for value in [128, 64, 32, 16, 8, 4, 2, 1]:
if n >= value:
bits = bits + "1"
n = n - value
else:
bits = bits + "0"
return bits
for n in [77, 5, 200]:
print(to_binary(n))
for bit in to_binary(77):
if bit == "1":
tone(880, 0.2)
else:
tone(440, 0.2)
wait(0.1)
Any program that meets the task's checks is marked correct in the simulator; this is one way, not the only way.