Method for dynamic bandwidth testing

A method for dynamic bandwidth testing of a link between two computer subsystems, comprising the steps of:

• providing circuit modules within each subsystem to couple the subsystem by a bi-directional multi-bit (BiDi) link, and
• providing within each said circuit module a built-in circuit and logic for dynamic transmission characterization and test of a said BiDi link between computer subsystems using built-in characterization logic macros, and
• during a test mode, switching said built-in circuit and logic to test mode and using the test mode to characterize the link performance, and after the completion of characterization, the switching built-in characterization logic macros back to a normal system mode after programmatically setting timing parameters for the BiDi link to ensure safe operation of data transfer before the BiDi link is switched to system mode, wherein said built-in characterization logic macros are linked by said BiDi whose bandwidth and data transmission parameters are to be characterized, and there are two macros, each of which macros have identical bit slices and a number (W) of bit slices equal to the bit width (W) of the BiDi, such that each macro has W bit slices;
• and wherein each macro has two sets of shift registers, one sender shift register set having W shift registers controlled by a sending signal for sending and one receiver shift register set having W shift registers controlled by a receiving signal for receiving serial data.