28-08-2013, 04:43 PM
Sharing of Data on DOS machines
Data on DOS machines.pdf (Size: 81.15 KB / Downloads: 18)
Transfer data from machine A to machine
– DOS machines connected by a serial line.
– machine A: copy file to the com1 port
– machine B: copy com1 to file.
• Issues:
– Synchronisation
• if sender is faster than receiver
– Error on the line
• require error checking
A Solution
• Solution (a):
– Synchronisation: interrupt driven
– Error: check sum, CRC, parity
– Overflow: flow control
• sender sends data at the rate at with receiver is
ready accept.
Issues
• If read at A is faster than get at B
– read at A is completed before RTS is reset by B.
– A will transmit another byte.
– B will be swamped by A.
• One more signal is required:
– RTS alone is not sufficient.
– CTS (Clear To Send) A Î B
– RTS (Request To Send) B Î A