Method for performing inter-unit data transfer operations among a plurality of input/output bus interface units coupled to a common asynchronous bus

Claim 1

A method of performing a unit operation over an asynchronous bus that interconnects a first master input output bus unit (IOBU1) to a second slave input output bus unit (IOBU2), said unit operation allowing said bus units to asynchronously exchange application data and commands via said asynchronous bus without intermediate synchronous storage of data, said asynchronous bus including control line means for the asynchronous exchange of handshaking signals between said bus units, an address data (A/D) bus, a command status (C/S) bus, and an origin destination (O/D) bus, said method comprising the steps of: (a) assigning ownership of said asynchronous bus to said master bus unit (IOBU1) responsive to a request therefrom on said control line means; and (b) transmitting information between said IOBU1 and said IOBU2 via said asynchronous bus in three cycles including a select cycle followed by two data cycles, said information including at least one of a first part of said information, a second part of said information, and a third part of said information, wherein said first part of said information includes machine dependent data during said select cycle and includes said application data during both said data cycles that are transmitted between said IOBU1 and said IOBU2 on said A/D bus, said second part of said information includes a unit operation command during said select cycle and includes a completion status signal from said IOBU2 at the end of the second said data cycle that are transmitted between said IOBU1 and said IOBU2 on said C/S bus, and said third part of said information includes a parity signal or a slave bus unit address during said select cycle and a bus unit address during both said data cycles that are transmitted between said IOBU1 and said IOBU2 over said O/D bus; and (c) scheduling said three cycles so that said select cycle is asynchronously initiated responsive to completion of said assigning step (a) and asynchronously terminated responsive to the asynchronous exchange of a first said handshake signal between said bus units, the first said data cycle is asynchronously initiated responsive to termination of said select cycle and asynchronously terminated responsive to the asynchronous exchange of a second said handshake signal between said bus units, and the second said data cycle is asynchronously initiated responsive to termination of said first data cycle and asynchronously terminated responsive to said completion status signal from said IOBU2 on said C/S bus.

Claim 2

A method of performing a unit operation over an asynchronous bus that interconnects a first master input output bus unit (IOBU1) to a second slave input output bus unit (IOBU2), said unit operation allowing said bus units to asynchronously exchange application data and commands via said asynchronous bus without intermediate synchronous storage of data, said asynchronous bus including control line means for the asynchronous exchange of handshaking signals between said bus units, an address data (A/D) bus, a command status (C/S) bus, and an origin destination (O/D) bus, said method comprising the steps of: (a) assigning ownership of said asynchronous bus to said master bus unit (IOBU1) responsive to a request therefrom on said control line means; and (b) transmitting information between said IOBU1 and said IOBU2 via said asynchronous bus in three cycles including a select cycle followed by two data cycles, said information including at least one of a first part of said information, a second part of said information, and a third part of said information, wherein said first part of said information includes machine dependent data during said select cycle and includes said application data during both said data cycles that are transmitted between said IOBU1 and said IOBU2 on said A/D bus, said second part of said information includes a unit operation command during said select cycle and includes a completion status signal from said IOBU2 at the end of the second said data cycle that are transmitted between said IOBU1 and said IOBU2 on said C/S bus, and said third part of said information includes a parity signal or a slave bus unit address during said select cycle and a bus unit address during both said data cycles that are transmitted between said IOBU1 and said IOBU2 over said O/D bus; and (c) scheduling said three cycles so that said select cycle is asynchronously initiated responsive to completion of said assigning step (a) and asynchronously terminated responsive to the asynchronous exchange of a first said handshake signal between said bus units, the first said data cycle is asynchronously initiated responsive to termination of said select cycle and asynchronously terminated responsive to the asynchronous exchange of a second said handshake signal between said bus units, and the second said data cycle is asynchronously initiated responsive to termination of said first data cycle and asynchronously terminated responsive to said completion status signal from said IOBU2 on said C/S bus.