Homework: Bits and Bytes

1. The USB 1.1 specification supports transfer speeds up to 12Mbps. How many MegaBytes per second is this?

Answer: 1.5 Megabytes per second
(12 Mbps X 1 MBps/8 = 1.5 MBps)


2. The USB 2.0 specification supports transfer speeds up to 480Mbps. How many MegaBytes per second is this?

Answer: 60 MegaBytes per second
(480 Mbps X 1 MBps/8 = 60 MBps)


3. Firewire, another external bus specification supports data rates of up to 400 Mbps. Translate this to MegaBytes per second.

Answer: 50 MegaBytes per second
(400 Mbps X 1 MBps/8 = 50 MBps)

4. How many seconds will it take to transfer 100 MegaBytes using the Firewire bus, assuming a transfer rate of 400Mbps?

Answer: 2 Seconds
(100 MBps / 50 MBps = 2 seconds)

5. How many seconds will it take to transfer a 4 MegaByte file on a 56K modem (assume a transfer rate of 56Kbps)?

Answer: .028 Seconds
(56 Kbps / 1000 = .056 Mb
.056 Mb X 1 MB/8 = .007
.007 X 4 = .028)

6. How many seconds will it take to transfer a 4 MegaByte file on a Broadband line
(assume a transfer rate of 5Mbps - comcast residential service)?

Answer: 6.4 Seconds
(5 mBps/8= .625 Mb
4 Mb/.625= 6.4 seconds)