8-bits Parallel to 2x Nibble (4-bit each)
This component can be used to split a Byte into two Nibbles... either 4 higher bits (higher weight), either 4 lower bits (lesser weight).
The 74LS157 set the output with the adequate Nibble accordingly to the SELECT line.
This component can also be viewed as a big 4 bit switch where the output is set with the source A or the B.
Typical usage of this component is for retro-computing setup or been used when creating your own computer.
Note: the parallel port can send 8 bits but can only reads 4 bits through is error/signal pins to to receive data. In such condition, reading 8 bits of data requires some electronic trick and way to easily split a byte into nibbles to read 4 bits at the time on the parallel port. Github containing the kicad-public-projects/PARALLEL-BREAKOUT project with the parallel-bus board (prototype) allowing to read and write data on address/data buses.
- 8-bit Parallel input
- 4-bit Parallel output
- 8 bits to 2 nibbles (1 nibble = 4 bits)
- 5V logic
- Control logic
- SN74LS157 technical sheet (pdf)