Programmable controller with modular firmware for communication control

A communication control unit, useful in a data processing system including a data processor and a plurality of peripheral devices, each for communicating with said data processor through a different channel in accordance with a different communication discipline, each channel having a discipline identification line, said communication control unit comprising:

• a programmable controller module including:
• program memory means including a plurality of locations each storing an instruction, with sequences of instructions forming a first level of program control common to all peripheral devices for producing device address signals for addressing said channels and a second level of program control consisting of protocols stored in separate modules of said program memory means, each protocol consisting of communication discipline dependent routines unique to one or more of said peripheral devices, each protocol being stored in a separate module uniquely identified by a predetermined number of high order bits of an address;
• instruction register means;
• program address counter means for identifying a location in said program memory means and for transferring the instruction stored therein to said instruction register means;
• a read/write memory means for storing data;
• a data bus comprised of parallel bit lines;
• means responsive to instructions transferred to said instruction register means for operating on data either in said read/write memory means or appearing on said data bus;
• a plurality of input terminals, each terminal being connected to a discipline identification line of a device communication channel in accordance with the discipline of a device to which the channel is dedicated,
• a direct memory access module means responsive to instructions transferred into said instruction register for selectively transferring data from said read/write memory means to said data processor and from said data processor to said read/write memory means;
• and
• an interface adapter means coupled between said programmable controller module and said peripheral devices for receiving data from and transmitting data to said peripheral devices through different channels, one channel being dedicated to each peripheral device, said interface adapter means including means responsive to said device address signals from said programmable controller module for addressing said channels one at a time, and means responsive to said addressing means for activating the discipline identification line of the channel addressed at any given time to identify the protocol to be used in servicing the device to which the addressed channel is dedicated.

A programmable controller module for servicing a plurality of peripheral devices, said module having a plurality of device identification input terminals, each device for communicating in accordance with only one of a predetermined number of communication disciplines through a separate channel each channel having a discipline identification line, and each channel being addressable by said controller module, said controller module including a program memory means comprised of a plurality of memory modules for storing a control program arranged in two parts, each part having routines for providing a level of control for said devices, a first part stored in a predetermined number of memory modules for addressing any one of said device channels, and a second part having routines for servicing a number of device channels, routines of said second part being divided into a plurality of protocals, each protocol being comprised of discipline dependent routines to be used for servicing the different devices, and each protocol being stored in a separate one of said memory modules uniquely identified by a predetermined number of high order address bits, the remaining lower orders of an address identifying locations within a separate module, each device identification input terminal being connected to a discipline identification line of a channel in accordance with the discipline of a device to which the channel is dedicated, means responsive to said first part of said control program for addressing said channels one at a time, and means responsive to said addressing means for activating the discipline identification line of the channel, said programmable controller module including means responsive to said activated line for identifying the protocol to be used in servicing the device to which the addressed channel is dedicated.