Foreword

The schematics in this article are intended to give you
a chance to build your own UART (RS232 interface),
while avoiding 'proprietary technology'
by using standard 74LS/74HCT ICs.

Settings for this design: 8-N-1 at 19.2 kBaud.
What means: 8 Data Bits, no Parity Bit, one Stop Bit,
at 19200 Bits per second.

We are connecting to a PC like a modem would do.

Note, that this design is, more or less, only the core...
without RX/TX FiFos and such.

Supply pins of the ICs have been left out to make
the schematics look a bit simpler, please connect
the GND pin of each IC to GND, same thing for VCC.
Also try to place a 100 nF ceramic capacitor between
GND and VCC at each IC...

Here a simplified block diagram of the UART:

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