Abstract: Handshake control for data transfer in a computer system having a master unit connected to a bus adapter through an expansion bus, which bus adapter is connected to slave units through a main bus, is partly accomplished in the bus adapter to increase data transfer speed for the interlock mode. The bus adapter exercises control in such a way as to set the data strobe signal on condition that a data strobe output permission signal has been asserted and that at least one of a data strobe suppression pulse signal and a data acknowledge signal has been negated and to reset the data strobe signal when the data strobe suppression pulse signal is asserted. The transmission of the data suppression pulse signal is made by detecting the rise of the data acknowledge signal in the master unit and is asserted for a fixed time or pulse width corresponding to system standards.