1. A system for monitoring the performance of peripheral devices connected to and accessed by a central processing unit via a CPU channel of the type which carries data, addresses, commands, status information and a plurality of condition flags, comprising: a channel interface module connected as a peripheral device to said channel, said channel interface module comprising data selector means for receiving all said data, address, command and status information on said channel and providing same on a bus line output thereof, a signal level circuit connected to receive at an input thereof certain ones of said condition flags from said channel and for providing condition strobes at an output thereof in response to said certain ones of said condition flags, and event means connected to receive certain ones of said condition flags from said channel and for providing input event codes representing selected sequences and combinations of said condition flags and an event code strobe in response to said condition flags received thereby; a data collection module connected to said channel interface module and comprising a packet memory, said data collection module being responsive to the information on said bus line output, said condition strobes and said input event codes for selectively collecting and generating and storing in said packet memory information about peripheral devices when said peripheral devices are accessed on said channel, and said data collection module comprising device utilization means responsive to address and status information from said channel interface module for generating, for each of selected peripheral devices connected to the channel, information representing the time period said peripheral device is operating, said device utilization means comprising, a first device utilization storage means having a plurality of storage locations therein, assigned to and corresponding to a plurality of peripheral devices, respectively, means for storing enable indicators in those of said storage locations of said first device utilization storage means corresponding to those of said peripheral devices, selected for utilization monitoring, status and address responsive means responsive to status information and address information for storing busy indicators in the said storage locations of said first device utilization storage means corresponding to said peripheral devices only during the period said devices, respectively, are operating, scanning means for periodically scanning all said storage locations of said first device utilization storage means corresponding to said peripheral devices; and second device utilization storage means, having plural accumulating locations assigned to and corresponding to said plurality of peripheral devices, for incrementing once per scanning period each said accumulating location for which said corresponding location in said first device utilization storage means contains an enable indication and a busy indication.