GATE IT 2004 | Question: 11, ISRO2011-33

Question

What is the bit rate of a video terminal unit with $80$ characters/line, $8$ $\text{bits/character}$ and horizontal sweep time of $100$ $\text{µs}$ (including $20$ $\text{µs}$ of retrace time)?

• A. $8$ $\text{Mbps}$
• B. $6.4$ $\text{Mbps}$
• C. $0.8$ $\text{Mbps}$
• D. $0.64$ $\text{Mbps}$

Comments

Removed according to https://gatecse.in/gate-cse-2016-syllabus/#Operating_System

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i/o scheduling is present in syllabus(2023). See the syllabus from official website.

Doubt: i/o scheduling and i/o handling different???

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@GateOverflow04 They are part of I/O which is in syllabus.

Answer 1

Answer: (B)

Bit rate of a video terminal unit $= 80 \times 8$ bits$/100 µs = 6.4$ Mbps

Comments

@VS

why u exclude retrace time?

https://www.keysight.com/main/editorial.jspx?cc=IN&lc=eng&ckey=593152&nid=-34000.901862&id=593152

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do we have to include retrace time for calculating bit rate of the video terminal? Because in retrace period video terminal unit does not sends bits to the terminal @srestha

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srestha mahabir10

I think in this question 20 micro sec of retrace time is included in 100 ......hence we have to consider 100
morever 640/120=5.33 no option match so retrace is included in 100 as per question

Answer 2

bit rate is the count of bits per second.

$80$ $characters$ =====>$100µsec$

$80\times 8$ $bits$======>$100µsec$

$640$ $bits$=======>$100µsec$

$1µsec$=======>$6.40$ $bits$

$1\times10^{-6}  sec$=====>$6.40$ $bits$

$1 sec$====>$6.40\times 10^{6}$ $bits$

   $bit$  $rate=6.40Mbps$

Comments

What is the use of retrace time given in the question?