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This is the H89/USB Adapter prototype board constructed by Chris Elmquist. The FTDI FT-245 USB FIFO card is mounted on perfboard along with a 74LS138 TTL IC for decoding adapter addresses and functions and a 74LS125 TTL IC for gating FIFO status onto the data bus for sampling by the H89. Dimensions are approximately 2 1/4" by 3". The prototype is a two-board stack held together by separaters fastened with the two screws seen in the photograph. The "lower" perfboard helps with real estate management and holds the 40-pin connector that plugs into the 8250 socket on the serial card.