RUEYSEN LIN
Broker in Lexington, MA

4965793, Oct 23, 1990

Feb 3, 1989

7/306862

R. Stephen Polzin - Holden MA
Roger G. Niles - Marlboro MA
Rueysen Lin - Lexington MA

Digital Equipment Corporation - Maynard MA

H04J 324

370 941

To interface a system control unit with an input/unit in a computer system, an interface includes a transmitter for sequentially transmitting data packets and parity signals between the system control unit and the input/output unit, and a receiver for sequentially receiving the data packets and parity signals. The receiver includes a buffer for storing a plurality of the data packets. The stored data packets are controllably unloaded from the buffer, and a buffer emptied signal is sent back to the transmitter as each data packet is unloaded. The transmitter has a counter which calculates the number of data packets stored in the buffer and asserts a signal that prevents the transmitter from transmitting additional data packets when the buffer becomes full. The receiver compares the parity of the received data packets to the respective parity signals to check for parity errors. The receiver sends an acknowledge signal back to the transmitter in the absence of a parity error, and sends a retry signal back to the transmitter in the presence of a parity error.

5146564, Sep 8, 1992

Feb 3, 1989

7/306325

Michael B. Evans - Marlboro MA
Rueysen Lin - Lexington MA
Brian F. Rost - Northboro MA
R. Stephen Polzin - Holden MA

Digital Equipment Corporation - Maynard MA

G06F 1300

395250

A computer system includes a plurality of central processing units (CPUs), a main memory, a system control unit (SCU) for controlling the transfer of data between the CPUs and the main memory, and a service processing unit (SPU) to interface the computer system with the outside world, such as an operator console. The method used for interfacing the SPU and SCU includes delivering a BUFFER FULL handshaking signal from the SPU to the SCU in response to the SPU receive buffer having data contained therein and being unavailable to receive data. The SCU responds to the absence of the BUFFER FULL handshaking signal by delivering a TRANSMIT FRAME handshaking signal to the SCU. A preselected duration of time after delivering the transmit frame, the SCU delivers the actual data in a series of fourteen consecutive clock cycles. Further, the method for delivering data from the transmit buffer of the SPU to a receive buffer of the SCU includes delivering a BUFFER REQUEST handshaking signal from the SPU to the SCU in order to determine if a buffer is currently available in the SCU. When a receive buffer grant becomes available in the SCU, a buffer grant handshaking signal is delivered to the SPU.