2031 LP CIRCUIT THEORY

IEEE Interface

All of the signals on the interface are controlled by the I/O device UAB1. Eight parallel bi-directional data lines, PA0- PA7, are used as the parallel data bus for the interface. UA2 is an octal bus transceiver used to provide communication on the general purpose interface bus, GPIB, between operating units of the system. The data transfer and bus-management signals are communicated by UA3, thus completing the 16-line interface of the IEEE-488 bus.

DAV	Data Valid	DAV low signifies data is valid on the data bus.
E01	End or Identity	CBM always sets E01 low while the last data byte is being transferred.
DAC	Data Not Accepted	DAC is low when data is being read and returned high after the last data byte is read.
RFD	Not Ready For Data	RFD is low until all receivers are ready to accept data, then the line will go high.
SRQ	Service Request	Not implemented in BASIC but available to the CBM user.
ATN	Attention	The host sets the signal low while sending commands on the data bus.
REN	Remote Enable	REN is held low by the bus controller and the host has this pin per-manently grounded.
IFC	Interface Clear	The host sends its internal reset signal as IFC low to initialize all devices.