Figure 1-35.—AN/UGC-143A(V)4 ASR keyboard.

The electronic module controls the functional operations of the NST and provides temporary storage of all transmitted and received information. It contains a message buffer memory, message segmentation logic, message routing logic, communication port, crypto port, and power supply. The buffer compensates for varying baud rates and holds incoming traffic until the entire message has been received, and then sends it to the printer. The printer module contains the printer mechanism, printer electronics, printer buffer, status indicator, system setup switches, and power supply. All received or transmitted information may be automatically printed. The operator can interrupt the printing mode without losing incoming message traffic to print directory information or internal systems test results. A dot-matrix print mechanism is capable of printing line lengths up to 80 characters at a speed of 120 characters per second (1200 WPM). (Until all Model 28 teleprinters have been replaced ashore and afloat, only 69 characters are allowed in a single message line.) Operator-selected, single- or double-line spacing modes are available. The printer uses either friction- feed nonperforated or tractor-feed perforated fan-fold paper. It is capable of accommodating single-ply paper or five-ply paper. The keyboard module contains the basic complement of keys needed to send characters, release tape reader input, and perform tape editing. Another variation of the keyboard module includes a one-line (80-character) LCD display and special function keys that help the operator in message preparation and correction (fig. 1-35). The gray shaded keys are command or edit functions. Many of the remaining keys contain message functions, accessed by holding down the "shift" key as the function is depressed. Notice that the keyboard contains carriage return (CR), line feed, letters (LTRS), and figures (FIGS) keys, similar to the older Model 28 keyboards. The bulk storage module contains the tape drive, drive electronics, message file logic, bulk storage buffer, function control switches, and power supply. It automatically stores all received and transmitted messages on a removable data cartridge. This module maintains an archive directory listing (table ofcontents) of all messages stored. The operator can have the table of contents printed or displayed on the keyboard module screen. The table of contents lists the messages in date-time group order and includes the originator, NAVCOMPARS processing sequence number (PSN), and an access number by which the operator can recall the message from storage. A data cartridge tape can store up to 1,344 messages of 2,000 characters each. Figure 1-35.—AN/UGC-143A(V)4 ASR keyboard. 1-45