In-Circuit/Functional Testing of Microprocessors on Printed Circuit BOARDS
Original Publication Date: 1985-May-01
Included in the Prior Art Database: 2005-Feb-18
High speed microprocessors, which are mounted on printed circuit boards, are tested at full speed with a board tester having a much slower speed. Each microprocessor on a printed circuit board under test has a RAM BOARD inside a bed-of-nails test fixture used with a board tester. As shown in Fig. 1, each RAM BOARD includes an address latch, a random-access memory (RAM), disconnect relays, an uncommitted relay, and miscellaneous logic. The uncommitted relay can be used for loopback tests on serial input/output ports. The disconnect relays are open during the microprocessor test to keep the fixture wiring length less than 500 millimeters on the address lines, data lines, and control lines.