Hey guys, me and my buddy are working on the 8 bit computer project and weve built register A, B and the Instruction register. We went through testing each register individually by pulling up the respective bit on the bus with a test switch, individually the registers work as intended but when we try to load bits into them at the same time they dont like to play together. 

For testing we set all 4 gate gaurds to the 173's low. The 245's also have been set to high impedance state so i wouldn't think they would be affecting the circuit. We have also installed 10k ohm pull down resistors from each bus to ground. The values we saw in testing made no sense as the lights seemed to lightup randomly and even change with nothing on the bus. 

I dont have an oscilloscope to actually measure whats happening on the bus with each clock pulse but i wouldnt think trying to load a value into both registers at the same time would cause any issues. 

Additionally our instruction is also having trouble. When trying to load a value into the instruction register with the same method all output lights for the respective 173 come on, even though only 1 bit on the 173 is pulled high. This part specifically doesnt make much sence to me as the bus bit lights are off and when measuring the bus voltage it shows about 0.7v which should be significantly less than the 2v needed for the 173 to read the value as a logical 1 and save the bit. 

NOTE: We went ahead and soldered on the 220 ohm resistors to each LED, its not shown in the picture but in our testing they were there. 

Does anyone know why we might be seeing these results? 

Register testing