4703 Jun65

The 4703 Teletype Transmitter, developed by Digital Equipment Corporation in 1965, is a self-contained parallel-to-serial converter designed for asynchronous serial data transmission. Mounted on a double-length DEC System Module board, it transforms a 5-bit parallel character into a serial stream by adding a Start bit and a user-selectable Stop element (1.0, 1.5, or 2.0 units, configurable via jumpers).

Operationally, an external device reads a 5-bit character into the module's shift register. Once enabled and the previous character's stop time has elapsed, the module enters an "Active" state. It then transmits a Start bit, followed by the five data bits at one-unit intervals. Upon completion of the data bits, it transitions to an "Inactive" state, transmits the Stop element, and sets a "Flag" output, signaling to the external device that it has finished transmission and is ready for the next character.

The transmitter supports flexible interfacing with various digital devices, not just teletypes, and provides dual complementary data outputs. Its clock input should be twice the baud rate, with a maximum of 25 KC, allowing for baud rates up to 12.5 KC. A formula is provided to calculate the minimum character loading time based on the stop element length and baud rate. An indicator light visually displays the state of the Flag. The unit requires -15V and +10V power and was priced at $250.00 (non-catalog).