4706 Jun65

The DIGITAL EQUIPMENT CORPORATION (DEC) 4706 8-Bit Teletype Receiver, dated 6/14/65, is a serial-to-parallel converter designed for asynchronous serial data. Self-contained on a double-length DEC System Module board, it facilitates transferring data from an incoming serial teletype line (or similar device) to a parallel digital device.

Key Features and Operation:

• Data Format: It receives 8-bit data characters, accompanied by Start and Stop elements, forming a total transmission of 10.0, 10.5, or 11.0 units. The bit immediately following the Start bit is the least significant bit (Bit 1).
• Synchronization: The receiver monitors the line 8 times per unit. Upon recognizing a valid Start element (filtering out noise shorter than 0.5 units), it enters an "Active" state, resets its shift register, and synchronizes to sample subsequent data elements at their center.
• Data Assembly: Data elements are gated into a shift register. Once all 8 data bits are assembled, a "Flag" is set, indicating to an external device that a complete character is ready for sampling. The Flag can then be cleared.
• Inputs: Requires a Clock input (8 times the baud/bit frequency, up to a maximum of 100 KC, supporting baud rates up to 12.5 KC), an Enable signal, a Data Input (Mark = ground, Space = -3V), and a Clear Flag signal.
• Outputs: Provides 8 data bits, an "Active" output (negative from start time until 0.5 units into the Stop unit), and a "Flag" output. Output levels are DEC Standard and jumper-configurable.
• Configuration: Internal jumpers allow for selecting Stop element length (1, 1.5, or 2 units), setting Flag clearing behavior (on Start pulse recognition), and connecting the Active output.
• Indicators: An onboard indicator lamp provides visual feedback on the Flag's state.
• Power: Operates on -15V (200mA) and +10V (6mA).

The module can also serve as an interface between computer systems or with measuring devices that produce compatible serial data.