// ChatAudio.d
// Copyright Xerox Corporation 1979

//	Last modified April 13, 1979  5:13 PM

structure ACB:  // Audio Control Block
[
base word	// -> base of ring buffer
end word	// -> first word beyond end of buffer
read word	// -> next word to read
write word	// -> next word to write
duration word	// used to count down duration
interval word	// interval timer interval, shifted appropriately for SIT
data word	// temp--holds data being output to Diablo printer interface
timeMask word	// mask for interval timer time word (Alto I/II)
sitShiftCount word  // shift count to position interval properly (Alto I/II)
]
manifest lenACB = size ACB/16

manifest
[
// page 1 locations for controlling interval timer
itTime = #525		// time at which next interrupt is to occur
itInterruptMask = #423	// interval timer interrupt mask
]