RFC 311 UNKNOWN HARDWARE · TERMINAL · I/O INTERFACE

New Console Attachments to the USCB Host

Adding I/O ports to UCSB's IBM 360/75 computer for multiple terminals

On rfc-editor.org ↗
PUBLISHED
February 1972
AUTHORS
R.F. Bryan
STREAM
Legacy
I/O CONNECTIONS
32 (grouped in 16 pairs)
INPUT BUFFER SIZE
16 bits
OUTPUT BUFFER SIZE
32 bits
SIGNAL STANDARD
EIA RS-232
DOI
10.17487/RFC0311

RFC text

Original text · RFC Editor View on rfc-editor.org ↗
                                                  UCSB Computer
NETWORK WORKING GROUP                             Research Lab.
REQUEST FOR COMMENTS # 311                        Roland F. Bryan
NIC #9341                                         29 February 1972


                NEW CONSOLE ATTACHMENTS TO THE UCSB HOST



   The MLC/360M
   ---------------

   The UCSB 360-75 is equipped with an interface unit that allows
   attachment of any type of I/O device to the Multiplexor Channel and
   for that device to be operated by program control as though it were a
   standard IBM Control Unit.  The interface, referred to as the
   Multi-Line Controller/360M (MLC/360M), operates on the Multiplexor
   Channel and provides 32 independently addressed I/O connections that
   are grouped into 16 pairs to accommodate full- duplex I/O operation.
   Each input group has a 16-bit input buffer plus related synchronizing
   and control logic to make it a stand-alone control unit on the 360
   channel.  Similarly, each output group has a 32-bit buffer plus logic.
   Attachment is achieved by connection through a data-set type connector
   and I/O signal levels conform to EIA standards (RS-232 Spec.).


   Both the I/O group hardware and the supporting software for the
   MLC/360M are readily modified to produce any variations required for
   attachment and operation of non-standard devices.


   Since our primary support was for 201B data-sets at 2400 baud, we
   first implemented the 16 I/O group pairs to accommodate this type of
   modem in our time-shared user environment.  The I/O groups have now
   been variously modified to support a wide range of applications, from
   300 baud acoustic coupled use to 9600 baud for multi-station classroom
   operation.



   New Consoles
   ---------------


   In addition to our standard attachments, which are mostly Culler-Fried
   graphic display consoles and educational classrooms
   using such consoles, we have a Tektronix 4002A and an NIH General
   Purpose Graphics Terminal (GPGT).


   The Tektronix terminal can now be operated on the ARPANET and will
   provide our users with upper and lower case ASCII for easier operation
   with other sites.  A report on this console's capability will be
   forthcoming.


   The GPGT was developed by the University of IOWA for use in
   Bio-Medical applications.  The unit is a delay-line refreshed video
   display with graphic capability and is the only dynamic type display
   in use on our host computer at present.  We are evaluating its
   performance in our On-Line System environment.  Since a user at this
   terminal is also able to reach into the network, we will have some
   future comments on its operation for interested persons.













       [ This RFC was put into machine readable form for entry ]
       [ into the online RFC archives by BBN Corp. under the   ]
       [ direction of Alex McKenzie.                   12/96   ]

AI ELI5

On this page
PROBLEMUCSB's IBM 360/75 computer had limited I/O connections and needed to support many different kinds of terminals and devices.
MECHANISMUCSB designed the MLC/360M (Multi-Line Controller/360M), an interface unit that provides 32 independently addressed I/O connections in 16 pairs, using standard EIA RS-232 signal levels for compatibility with modems and terminals.
FLEXIBLE EXPANSION SOLUTIONThe system proved flexible enough to support everything from 300 baud acoustic couplers to 9600 baud classroom use, including Tektronix display terminals and specialized graphics equipment.

§1The MLC/360M Interface

UCSB's IBM 360/75 computer needed a way to connect many different I/O devices. The Multi-Line Controller/360M (MLC/360M) is an interface unit attached to the computer's Multiplexor Channel that provides 32 independently addressed I/O connections grouped into 16 pairs for full-duplex communication. Each input group has a 16-bit buffer and each output group has a 32-bit buffer.

The MLC/360M gives the computer 16 pairs of plugs, so 16 devices can talk to it at the same time.

§2Standard Signals for Easy Compatibility

The interface uses EIA RS-232 signal levels, the standard for data communication equipment of the era. This allowed attachment of common devices like 201B data-sets at 2400 baud. The hardware and software are designed to be easily modified for new device types, making it adaptable to a wide range of uses.

The system uses a standard plug type, so many different devices can work with it.

§3Support for Many Terminal Types

The MLC/360M proved flexible in practice. In addition to the standard Culler-Fried graphic display consoles used in educational classrooms, UCSB successfully attached a Tektronix 4002A terminal capable of upper and lower case ASCII, and the NIH General Purpose Graphics Terminal (GPGT), a delay-line refreshed video display with graphics capability developed at the University of Iowa for biomedical applications. The system has been used at speeds from 300 baud acoustic couplers to 9600 baud for multi-station classroom operation.

Many different kinds of displays and terminals worked with it, from slow acoustic couplers to fast classroom terminals.