MSB DDDDDDD
7. COMMUNICATIONS SUBSYSTEMS
The two basic communications subsystems available for the UNIVAC 418-111 System are the Word Terminal Synchronous and the Communication Terminal Subsystem.
The Word Terminal Synchronous operates in Internally Specified Index mode and is used to connect a single high speed synchronous communication line to a single 10M channel. The Communication Terminal Subsystem operates in Externally
Specified Index mode and is used to terminate a wide variety of low, medium, and/or high speed communication lines. The number of lines per Communication Terminal Subsystem depends on the speed of the lines connected. Each subsystem connects to a pair of 10M channels.
7.2. COMMUNICATION TERMINAL SUBSYSTEMS
The Communication Terminal Subsystem consists of the Communications Terminal Module (CTM) which makes direct connection with the communications facility and the Communications Terminal Module Controller (CTMC) through which the CTM's deliver data to and receive data from the UNIVAC 418-111 System. The CTMC may be connected to any pair of channels on an Input/Output Module (except channels
o
and 1). The num ber (maximum 16) of CTM's which may be connected to a C TMC depends on the CTM and the speed and type of communication lines to which they connect.7.2.1. Communications Terminal Module
The three basic types of Communications Terminal Module (CTM) are the low speed communication lines. These lines may operate in simplex, half-duplex, or full-duplex mode. The basic low speed CTM's provide for line termination with a minimum of line control capability. The enhanced low speed CTM's provide for end-of-transmission recognition, as well as other transmission control functions.
There are basic and enhanced medium and high speed CTM's. Some of the enhanced control capabilities are character and message parity generation and checking, end-of-message recognition, and a CTM for automatic dialing control. These CTM's provide for connection to DAT A-PHONE* service and Broadband** service, private line and private wire service, and Wide Band Data Service and Wide Band Channel and Service, as well as other available line speeds.
* Service Mark of the Bell System
**
7.2.2. Communications Terminal Module Controller
The function of Communications Terminal Module Controller (CTMC) is to provide housing and connection of up to 16 CTM's to a paired channel of an Input/Output CTMC automatically assigns priority among the CTM's requesting access and
it2""!"'t;f;pc:. to thp Tn!Hlt/Output Module the particular CTM being granted access.
This identification is used by the 10M as the basis for Externally Specified Index-ing. The process of data transfer is automatic and self-controlling among the CTMC, the 10M, and main storage and does not require the use or intervention of the
Command/ Arithmetic Unit.
7.3. WORD TERMINAL SYNCHRONOUS
The Word Terminal Synchronous (WTS) complements the UNIVAC 418-III communications subsystem by enabling it to be used more efficiently for high-speed data transmission
This high-speed transmission capability, coupled with the ability to dial connect with any station on the public network complex, handles many of the data communica-tions problems. The WTS allows the UNIVAC 418-II1 System to exchange data with a remote computer. This configuration can be used for order, entry, and inventory control,and more important, for remote processing capabilities.
7.3.1. Operational Modes
There are three basic modes of operation (leased line high speed .. Dial network high speed, leased line Broadband) which can be used with the WTS.
• Leased Line High Speed
Leased telephone line operation permi ts continuous data exchan ge between two fixed locations at a maximum transfer rate of 300 characters per second .
• Dial Network High Speed
A number of high speed stations can be connected to a WTS, one at a time over dialed (DDD) network circuits. Dial network operation permits data exchange between any two subscriber locations, beginning with a connection procedure (dial) and ending with a disconnect procedure (hang up). Transfers may be initiated by either the WTS or the remote station. If the WTS initiates the
trans-fer, the connection is made automatica lly by the C/ A Unit through the auto-matic calling option available on the WTS. The remote station autoauto-matically answers the call and data transfer can commence. If the remote station initiates the call, the WTS automatically answers the call utilizing the un-attended answering option. Data transfers can then take place in the normal manner. All data transfers over dial high speed circuits are at a maximum transfer rate of 250 characters per second.
• Leased Line Broadband
A single Broadband sta tion is connected to a WTS by a leased Telpak A
*
line. Leased Telpak A line operation permits continuous data exchange be-tween two fixed locations at a maximum transfer rate of 5,800 character per second. Data transfer can be initiated by either device, providing the remote hardware can handle such an operation. The data format is such that character parity, start and end-of-message limits, message parity and character synchro-nization are established. The WTS is prepared to receive data at all times.
These modes of operation reflect the influence of presently available com muni-cations tariff offerings. The WTS design and packagin g philosophy allows for higher speed operation and for operation with communications hardware using
more advanced techniques.
The D atasets (2 01-C, 2 01-D, 301-B) represent the latest versions of sets which have been on the market for some time. The 201-C succeeds the 201-A, the 201-D succeeds the 201-B, and the 301-B succeeds the 301-A. They are basically the same sets (speed, phy sical makeup, modulation techniques), these chan ges reflecting minor updating and modifications and, in the case of the 201-C, automatic dialing compatibility.
Speed
Data Coding Control Coding
Communications Faci lities
I/O Channe Is Required I/O Transfer Mode
* Trademark of the Bell System
2000,2400,4,800 bits/second
6 data bits per character
Control characters (Synch, Start-of-Message, End-of-Message, etc.) field selected by plugboard
Voice circuit dia I or leased at 2000, or 2400 bps respective Iyo Broadband lease at 50,000 bps.
1 per WTS
Fu II word basis (three 6-bit characters per transfer)