D-A12i 543 MICROPROCESSO IMPLEMENTATION OF OPTIONAL FUNCTIONS OF IniSYNCHRONOUS BIT-OR..(U) DELTR INFORMATION SYSTEMS INCJENKINTOWN PA S URBAN 19 MAY 62 NCS-TIB-82-3 N

UCASIFIED DC~iBe-Bi-C-825 .F/G 17/2 NmhhhhhONE2hhhhhhl0 111

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MICROCOPY RESOLUTION TEST CHARTNATIONAL BUREAU OF STANDAROS - 163 - A

ADA121.543NCS TIB 82-3

NATIONAL COMMUNICATIONS SYSTEM

TECHNICAL INFORMATION BULLETIN82-3

MICROPROCESSOR IMPLEMENTATIONOF OPTIONAL FUNCTIONS OF

SYNCHRONOUS BIT-ORIENTED DATALINK CONTROL PROCEDURES

DTICMAY 1982 ELECTE)L,NOV 15199 !

APPROVED FOR PUBLIC RELEASEDISTRIBUTION UNLIMITED

REPORT DOCUMENTATION PAGE READ INSTRUCTIONSRBEFORE COMPLETING FORM

I. REPORT NUMBER |2. GOVT ACCESSION NO 3. RECIPIENT'S CATALOG NUMBER

NCS-TIB 82-3 AP-Aia,-- SY. _ _ __

4. TITLE (and Subtitle) S. TYPE OF REPORT & PERIOD COVERED

Microprocessor Implementation of Optional

Functions of Synchronous Bit-Oriented Data FINAL

Link Control Procedures S. PERFORMING ORG. REPORT NUMBER

7. AUTHOR(s) S. CONTRACT OR GRANT NUMBER(e)

Steve Urban DCA100-81C0025

9. PERFORMING ORGANI1ZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT, TASK

Delta Information Systems, Inc. AREA & WORK UNIT NUMBERS

259 Wyncote RoadJenkintown, PA 19046

7" I. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE

National Communications System May 19,1982

Office of Technology and Standards 13. NUMBER OF PAGES

Washington, DC 20305 7314. MONITORING AGENCY NAME A ADORESS(If different from Controlling Office) IS. SECURITY CLASS. (of this report)

UNCLASSIFIEDr IS&. DECL ASSI FIC ATION/DOWNGRADING

SCHEDULE

16. DISTRIBUTION STATEMENT (of this Report)

Approved for Public Release; Distribution Unlimited

17. DISTRIBUTION STATEMEW-

(of the abtteoct etered In Block 20, If different from Report)

IS. SUPPLEMENTARY NOTES

19. KEY WORDS (Continue on reveree side It neceesry and Identify by block number)

Telecommunications Data Transmission Systems

Data Link Protocols, CommunicationsMicroprocessorsADCCP

20. AMTlACT (Cattm M revelm shb it nerwey and Identify by block number)'-This report contains a block diagram, flow charts, and computer programming

for the following optional functions in Federal Standard 1003 (Synchronous

Bit Oriented Data Link Control Procedures): Address Extention Function

for all three classes of procedures (Unbalanced Normal, Palanced

Asynchronous, and Unbalanced Asynchronous); Reset Function for the Balanced

Aysnchronous class of procedure only; Delete Command I Frame Function for

all three classes of procedures; Delete Response I Frame Function for all

three classes of procedures; unnumbered Polling Function for all three

DD 1473 DTflONOP t NOV 65 IS OSOLETE UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE (Wen Dote Entered)

S .,..: . *v-

classes of procedures..

FAccessi-on For

NTISGA&DTIC TABUnannounced

Just iticat io

Distribution/Availabiijty Codes

jAvail and/OX.Dist Special

UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE'nIeI Data Ente**

NCS TECHNICAL INFORMATION BULLETIN 82-3

MICROPROCESSOR IMPLEMENTATION OF OPTIONAL FUNCTIONSOF

SYNCHRONOUS BIT-ORIENTED DATA LINK CONTROL PROCEDURES

May 1982

PREPARED BY: APPROVED FOR PUBLICATION:

DELTA INFORMATION SYSTEMS, INC. MARSHALL L. CAIN310 Cottman Street Assistant ManagerJenkintown, Pennsylvania 19046 Office of NCS Technology

and Standards

FOREWORD

Among the responsibilities assigned to the Office of the Manager, NationalCommunications System, is the management of the Federal TelecommunicationStandards Program. Under this program, the NCS, with the assistance of theFederal Telecommunication Standards Committee identifies, develops, andcoordinates proposed Federal Standards which either contribute to theinteroperability of functionally similar Federal telecommunication systems orto the achievement of a compatible and efficient interface between computerand telecommunication systems. In developing and coordinating these standardsa considerable amount of effort is expended in initiating and pursuing jointstandards development efforts with appropriate technical committees of theElectronic Industries Association, the American National Standards institute,the International Organization for Standardization, and the InternationalTelegraph and Telephone Consultative Committee of the InternationalTelecommunication Union. This Technical Information Bulletin presents anoverview of an effort which is contributing to the development of compatibleFederal, national, and international standards in the area of data linkcontrol procedures. It has been prepared to inform interested Federalactivities of the progress of these efforts. Any comments, inputs orstatements of requirements which could assist in the advancement of this work,are welcome and should be addressed to:

Off ice of the ManagerNational Communications SystemATTN: NCS-TS (Frank McClelland)Washington, D.C. 20305(202) 692-2124

MICROPROCESSOR IMPLEMENTATION OF

OPTIONAL FUNCTION OF SYNCHRONOUS

BIT-ORIENTED DATA LINK CONTROL

PROCEDURES

Final Report

Submitted To:

NATIONAL COMMUNICATIONS SYSTEM

Office of Technology and Standards

Washington, D.C. 20305

Contracting Agency:

DEFENSE COMMUNICATIONS AGENCY

Contract Number

DCAI00-81-C-0025

May 19, 1982

Submitted By:

D E L T A I N F 0 R M A T I 0 N S Y S T E M S, I N C.

310 Cottman Street

Jenkintown, Pennsylvania 19046

TABLE OF CONTENTS

Page

1.0 Introduction 1-1

2.0 System Design Considerations 2-1

3.0 Address Extension Function 3-1

4.0 Delete Reset Function 4-1

5.0 Delete Command or Response I-Frame 5-1

6.0 Unnumbered Polling Function 6-1

7.0 Initialization Function 7-1

8.0 Unnumbered Information Function 8-1

9.0 References 9-1

ILLUSTRATIONS

Figure Page

2-1 System Block Diagram 2-2

2-2 Variables and Parameters 2-4

2-3 Read Data Byte Macro. 2-9

2-4 ISRREAD 6856 Protocol Chip 2-10

3-1 RCV Process 3-2

3-2 RCNTRL Subroutine 3-3

3-3 Extended Address Handler 3-4

3-4 Receive Process Code 3-5

3-5 RCNTL Code 3-10

4-1 Receive RSET Command 4-2

4-2 Transmit RSET 4-3

4-3 Receive RSET Command Code 4-4

5-1 SENDI Process 5-3

5-2 SENDI Process Code 5-5

5-3 Delete I-Frame Transmission 5-9

5-4 Delete Response I Transmission Code 5-10

5-5 Receive I Subroutine 5-12

5-6 Receive I Frame Code 5-13

6-1 Receive UP Command 6-2

6-2 Receive UP Command Code 6-3

6-3 SENDI Modifications for UP 6-6

6-4 SNDRNR Modifications for UP 6-7

7-1 Receive SIM Command 7-2

7-2 Receive SIM Command Code 7-3

7-3 Transmit RIM Response 7-6

7-4 Transmit RIM Command Code 7-7

7-5 Modification for SIM/RIM 7-10

8-1 Receive UI Subroutine 8-2

8-2 Receive UI Frame Code 8-3

4

I

I--

1.0 INTRODUCTION

This document summarizes the work performed by Delta

Information Systems, Inc. for the Office of Technology and

Standards of the National Communications System, an organi-

zation of the U.S. Government, under Purchase Order

DCA10O0- 8 1-C-0 025. The Of fice of Technology and S tandard s,

headed by National Communications System Assistant Manager

Marshall L. Cain, is responsible for the management of the

Federal Telecommunications Standards Program, which develops

telecommunication standards whose use is mandatory by all

Federal agencies. The objective of this program is to develop

a block diagram, flow charts, and computer programming

for the following tasks in accordance with Federal Standard

1003.

Address Extention Function for all three classes of

procedures (Unbalanced Normal, Balanced Asynchronous,

and Unbalanced Asynchronous).

-Reset Function for the Balanced Aysnchronous class

of procedure only.

-Delete Command I Frame Function for all three classes

of procedures.

-Delete Response I Frame Function for all three classes

of procedures.

-Unnumbered Polling Function for all three classes of

procedures.

-Initialization Function for all three classes of

procedures.

-Unnumbered Information Function for all three classes

of procedures.

The purpose of this effort is to determine the feasibility

of using the M6800 or similar microprocessor to implement

this type of protocol, and to obtain an estimate of memory

and processor resources that would be required. The office

of Technology and Standards will use the information to

advise other Federal agencies who implement the standard

and, when merged with the results of other studies, to evaluate

the operational and economic impact of incorporating various

options in Federal Standard 1003.

The effort necessarily has focussed on the software

required to implement the protocol itself, and is by no

means a total hardward/software system design that would be

required to develop a complete system. Complete system

development is, of course, beyond the scope of this program.

Section 2 of this report contains a discussion of the

method of implementation for the seven listed options and

a list of state variables and parameters. Sections 3 through

8 include flow charts, code and a discussion of memory

requirements and throughput for each of the options. The

code was assembled on a 6800 cross-assembler and tested on

* 1 6800 microcomputer supplied by Delta Information Systems.

1-2

2.0 SYSTEM DESIGN CONSIDERAI'IONS

The block diagram in Figure 2-1 shows a link with one

primary/combined and one secondary/combined station communicating

with eich other by sending information in both directions. That

is, either station may be a source or sink of data or both.

Two-way simultaneous transmission is assumed. Although manyI'

secondary stations may communicate with one primary station,

the objectives of this program can be met with no loss of

generality, by assuming the existence of only one secondary

station.

Each station, primary, secondary, or combined is made

up of a microcomputer, an LSI interface to the link, and a

user which supplies and uses the data to be communicated. The

primary and secondary stations Are physcially very similar;

operationally, of course, the primary must supervise and control

a number of secondary stations, and thus it requires a larger

data structure and somewhat more complicated code.

For the purpose of this program, the microcomputer

can be assumed to be very basic-microprocessor, memory (RAM

and ROM), interface chips, clock, etc. A discussion of

the interface chips, operating system considerations and

general design features may be found in a previous report. (1)

The objective of this effort is to determine the

incremental change in the number of instructions and processor

time required for each of seven optional functions listed

above, implemented on a Motorola 6800 microprocessor. These

2-1

AA

II-

6I 2-2Fl]

optional functions are achieved by the addition, or deletion,

of commands and responses with respect to those present in

one of the three basic classes of procedures.

No attempt has been made to produce a single basic

design to accomodate all of the options one at a time or

in combinations; in other words, each option is implemented

starting from the same previously designed baseline so that

the effect on memory requirements and throughput can be

evaluated for each option.

Detailed flow charts and code for each option are

compared with those of the baseline system to obtain the

differenrce in memory requirements and throughput.

Those state variables and other parameters that are

used by more than one routine and included in the code in

the following s~ctions are defined in Figure 2-2. A discussion

of these may be found in Reference 1. Two of the flow charts

in this previous report required some minor changes. These

are included in Figures 2-3 and 2-4.

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N-

3.0 ADDRESS EXTENSION FUNCTION

This option provides for greater than single octet

addressing by means of the Extended Address Format. The

extended format provides an address field which is made up

of a sequence of octets, each having a "0" (Zero) as the

first bit of the octet except for the last octet which has

a "1" in the first bit position.

Processing of the received address is accomplished in

the Receive Process (RCV). The flow chart for the RCV

process is shown in Figure 3-1. A major subroutine called by

RCV, the RCNTRL subroutine which processes the control field,

is given in Figure 3-2. An expanded flow chart of the

extended address handler is given in Figure 3-3. The 6800

assembly language code for the RCV process and the RCNTRL

subroutine is presented in Figures 3-4 and 3-5 respectively.

The number of instructions required to perform the

extended address can be estimated by examining Figure 3-4.

The code for address processing is included in lines 52

through 132. Examination of this code shows that few (less

than ten) additional instructions are required to perform

the extended addressing function as opposed to single octet

addressing. The extra processing time required to handle the

extended address is negligible; however, there is a minor

effect on throughput due to the increase in message length.

The effect is vezy small for I/UI frames azd somewhat larger

for supervisory and other unnumbered frames.

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4.0 DELETE RESET FUNCTION

This option removes the ability to reset the Send and

Receive variables associated with only one 4irection of

information flow by the deletion of the RSET command. This

applies to the Balanced, Asynchronous class of procedures

only.

Processing of the Reset function (RSET) is accomplished

in the two routines RSET and TR-RSET used respectively for

receive and transmit. Flow charts for these two routines are

presented in Figures 4-1 and 4-2. Assembly language code

for the receive RSET function is shown in Figure 4-3. If

the RESET function is deleted, neither the receive nor

transmit routines are required, resulting in a reduction of

approximately 32 instructions (64 bytes) for receive and

about 40 instructions for transmit. Since the transmission

of the RSET command by a combined may be used to report an

invalid N(R), some minor changes in the use of the FRMREJ

subroutine may be implied. Effects on throughput are difficult

to estimate at this level of implementation.

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5.0 DELETE COMMAND OR RESPONSE I-FRAME

These two options limit the procedure to allow I

frames to be commands only, or responses only, by deleting

the I response and the I command respectively. This tech-

nique limits information frames to one direction for

primary and secondary stations.

These options are treated together in this section,

because the main effect of each is the same: one station

loses the ability to transmit I-frames and the other loses

the ability to receive them.

The SENDI process is used to transmit I-frames (Refer

to Figure 5-1) both as commands and responses. The code

for this process is presented in Figure 5-2. If I-frame

transmission is deleted, the SENDI process is as shown in

Figure 5-3. The 6800 code corresponding to the flow chart

of Figure 5-3 is shown in Figure 5-4. The difference in

number of instructions between these tbwo routines is

approximately 100 instructions. In addition to this

reduction the CHICPNT routine can be deleted together

with references to it in RR and RNR, removing an additional

60 instructions for a total of 160 instructions. Throughput

can nearly be doubled if information transmission is limited

to one direction based on the fact that the processor need

manage half the number of buffers and pointers.

The flow chart for receiving I-frames is shown in

Figure 5-5, and the corresponding code in Figure 5-6. If

5-1

I-frames are not to be received, this routine can be

removed completely, saving approximately 75 instructions.

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6.0 UNNUMBERED POLLING FUNCTION

Option 6 provides for the ability to perform unnumbered

group polling as well as unnumbered individual polling by

the addition of the UP command. The UP command is used to

solicit a response frame from a single station, or from a

group of stations, by establishing a logical operational

condition that exists at each addressed station for one

respond opportunity.

The flow chart for the reception of the unnumbered

polling command and the corresponding 6800 assembly

language code are presented in Figures 6-1 and 6-2 respectively.

Approximately 20 instructions are required for this routine.

The receive UP function also requires some minor modification

to the SENDI process and the processes for sending Receive

Ready/Receive Not Ready. These modifications are shown in

the flow charts of Figures 6-3 and 6-4. Effects on

throughput are difficult ot judge at this level of implementation.

6-1

-UP

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Figure 6-1. Receive UP Command

6-2

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7.0 INITIALIZATION FUNCTION

This option provides the ability to initialize remote

stations and the ability to request initialization. The

SIN command and the RIM response are added. The SIM command

is used to request a remote station to initiate a station-

specified procedure to initialize its link-level control

function. The RIM response is used by the Secondary/

combined station to request the SIN command.

The flow chart for the reception of the SIN command

and the corresponding 6800 code are given in Figures 7-1

and 7-2. The flow chart for the transmission of the RIM

response and corresponding code are given in Figures 7-3

and 7-4. Some modification to the module that determines

the operational state is required to accommodate the

initialization state and the RIM condition. This module

is used at the beginning of the received commuand handlers

* for example, it appears in the received I-frame. The

modifications to this routine are shown in Figure 7-5.

7-1

CIA

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Figure 7-1. Receive SIM Command

7-2

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7-6

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7-1

8.0 UNNUMBERED INFORMATION FUNCTION

This option provides the ability to exchange information

fields without impacting the send and receive variables,

and provides for the addition of the UI command and the

I- Ul response. Since the frame is not sequence number verified,

the frame may be lost or duplicated if a link exception

condition occurs.

The UI function is very similar to the transmit I

function, assuming that a message is a number of bytes. The

Ut function requires no error recovery based on send and

receive variables nor buffering and pointers for multiple

frames. A flow chart for receiving UI and the corresponding

6800 code are given in Figures B-1. and 8-2. Comparing

Figure 8-2 with Figure 5-6 reveals the difference in code

required to send a Ut frame instead of an I frame. Of

course, a Ut frame may be sent in addition to an I frame.

8-1

I

to sioI

Figuze 8-1.. Refeive Ux Ssboutia*6-2

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9.0 REFERENCES

1. "Use of a Microprocessor to Implement an ADCCP

Protocol with Reject and Selective Reject"

(Federal Standard 1003) "Delta Information Systems,

Inc. August 1981.

2. "Use of a Microprocessor To Implement an ADCCP

Protocal (Federal Standard 1003)" Delta Information

Systems, Inc. July 1980.

3. Malcon Easton, "Batch Throughput Efficiency of ADCCP/

HDLC/SDLC Selective Reject Protocols" Data

Communications pp 187-195, February 1980.

9-1