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Test#1: Moving data between registers

For this test, I made 8-bits registers just for simplicity. In practice those will be 16 bits (using two 74C374 instead of one). Push buttons S_A, WR_A, S_B and WR_B simulate control signals (Select A, Write A, Select B, Write B respectively). Actually I did not use push buttons but momentary short-circuits made with wires. LED ON indicates logical 1; when "nothing" is in the bus, all LEDs go ON since bus lines are pulled-up to the power line (+5V).


The test went as following:

At the begin all LEDs were ON testifying a bus with all ones because of the pull-up resistors. By pressing S_A and S_B and could find what was stored at power-on into REG A and REG B respectively. They was all ones.

Using wires, I put some lines to ground in order to have some "data" over the bus. Then I pressed push button WR_A; this made my "data" to get latched into REG A. Then I remove the wires so the bus returned back to normal: all ones.

Now, I press S_A and S_B alternatively to see what is into REG A and REG B respectively. As expected, pressing S_A gave is my "data" back displayed by the LEDs; pressing S_B gave me the original all ones contained into REG B since the beginning of time.

The next step was to transfer my data from A to B. For doing that, I put the A content in the bus by pressing and holding S_A. In this conditions, I pressed WR_B momentarily. Finally I released S_A.

Now I repeated the regs reading by pressing S_A and S_B alternatively. Now both registers contained my data, as expected.

CONCLUSION

This test confirmed that I can build registers as planed: Wiring 74C374 chips as shown in the diagram (but combining two chips for 16-bits registers). It also confirmed the use of control signals S_X and WR_X for each register X.