I have for the last two or three months now studied cpu design and have read several books on making simple processors that start at the gate level.
I now wish to put my knowledge into practice!
I noticed that 74ls series chips have high speed switching capabilities and so I ordered some quad 2 input and, or, and xor chips.
I decided as a first project to build an 8 bit adder with them.
But I now have a slight problem...
I can not get them to do what I want them to do with the exception of the quad 2 input xor chip.
I cannot get the outputs of the chips to source any current at all as I have measured the voltage with a multimeter and they just will not source current for anything.
However I have been able to work the logic in reverse by sinking the current.
The "xor" chip works fine and I have no problems with it however the "and" chip logic functions like an "or" gate instead of an "and" gate. The or chip also does not work right.
My power supply is 5v regulated and the chip numbers are the following:
74LS08 - OR
74LS32 - AND
74LS136 - XOR
Any suggestions as to what's going wrong??
I now wish to put my knowledge into practice!
I noticed that 74ls series chips have high speed switching capabilities and so I ordered some quad 2 input and, or, and xor chips.
I decided as a first project to build an 8 bit adder with them.
But I now have a slight problem...
I can not get them to do what I want them to do with the exception of the quad 2 input xor chip.
I cannot get the outputs of the chips to source any current at all as I have measured the voltage with a multimeter and they just will not source current for anything.
However I have been able to work the logic in reverse by sinking the current.
The "xor" chip works fine and I have no problems with it however the "and" chip logic functions like an "or" gate instead of an "and" gate. The or chip also does not work right.
My power supply is 5v regulated and the chip numbers are the following:
74LS08 - OR
74LS32 - AND
74LS136 - XOR
Any suggestions as to what's going wrong??