Hello,
I have an old computer with a DB25 serial port. I want to add a DB9 connector and the ability to switch from one to the other. I know that converters exists and can be found for as cheap as $5, but I want to work on this project anyway.
I thought about using two 74157 quad 2-to-1 selector (or similar) ICs for the port inputs, and a 74255 dual 2-to-4 decoder (or similar) IC as seen in the schematic:
![db9-db25.png db9-db25.png](https://forum.allaboutcircuits.com/data/attachments/304/304563-9dc221f2d9f862b7d4f2b0a595d2d7c6.jpg)
My question is: is this going to work? The reason I'm using so many different ICs is that some pins are inputs, and some pins are outputs, and these ICs only work one way... but perhaps there exists a selector IC that works both ways and hopefully is a 16-to-8 (or 2 x 8-to-4) that I'm unaware?
I have an old computer with a DB25 serial port. I want to add a DB9 connector and the ability to switch from one to the other. I know that converters exists and can be found for as cheap as $5, but I want to work on this project anyway.
I thought about using two 74157 quad 2-to-1 selector (or similar) ICs for the port inputs, and a 74255 dual 2-to-4 decoder (or similar) IC as seen in the schematic:
![db9-db25.png db9-db25.png](https://forum.allaboutcircuits.com/data/attachments/304/304563-9dc221f2d9f862b7d4f2b0a595d2d7c6.jpg)
My question is: is this going to work? The reason I'm using so many different ICs is that some pins are inputs, and some pins are outputs, and these ICs only work one way... but perhaps there exists a selector IC that works both ways and hopefully is a 16-to-8 (or 2 x 8-to-4) that I'm unaware?