edited by
538 views
1 votes
1 votes
  1. Consider sending a large file of $360,000$ bits from Host $A$ to Host $B,$ connected through a router, as shown in the below figure $2.$ Assume that there is no queuing and propagation delay, and the router has sufficient buffer space. Host $A$ splits the file into segments of $S$ bits each and adds $36$ bits of header to each segment, forming packets of $(36+S)$ bits. Each link has a transmission rate of $R\: \text{bps}.$ Find the value of $S$ that minimizes the time needed to move the file from Host $A$ to Host $B.$
  2. The $CPU$ of a system having an execution rate of $1$ million instructions per second needs $4$ machine cycles on an average for executing an instruction. On an average, $50\%$ of the cycles use memory bus. For execution of the programs, the system utilizes $90\%$ of the $CPU$ time. For block data transfer, an $I/O$ device is attached to the system, while the $CPU$ executes background programs continuously. Determine the maximum $I/O$ transfer rate for each of the two cases: 
    1. programmed $I/O$
    2. cycle-stealing $DMA$ (in transparent mode)

You may assume that transferring one byte involves $4$ operations: in-status, check-status, branch and read/write in memory, each requiring one machine cycle.

edited by

Please log in or register to answer this question.

Related questions