COMPUTER NEWS (July/August, 1993)

General Enquiries     8592495
Computer Operation    8592496
(Hardware and operational problems)
'Help Desk'           8592480
(Software and general problems)
Fax                   5597904
Hardware Maintenance  8592774         
Dial-up to Data Switch
24-hr service line :  8592595
Night service line :  8597997

Operation Schedule for March 1993

Computer Centre Opening Hours

Normal Schedule

From June 13, 1993 to September 12, 1993  
From Monday (8:00 a.m.) to Saturday (4:00 p.m.)
Closed on Sundays and Holidays
Normal Schedule

From September 13, 1993 to June 13, 1994
From Monday (8:00 a.m.) to Saturday (9:00 p.m.)
Sunday from 12:00 noon to 7:00 p.m.
Closed on Holidays.  

VAX 6420 (HKUCC)           
DECsystem 5500s (HKUXA/HKUXB)                                  
SUN SPARCserver 670 (HKUSUB)                                           
Service hours
24 hours Daily.
Running unattended on all
Sundays and Holidays
Maintenance Schedule

VAX 6420 (HKUCC)        
September, 1993 (Wednesday)                        
Terminal Room Opening Hours

Remote Terminal Rooms   
Rm 218, Knowles Building
Rm LG-108, KK Leung Bldg.

SunOS & Ultrix Workstation Room
Rm 113, Run Run Shaw Bldg.
Rm 210, Run Run Shaw Bldg.

Microcomputer Laboratories
Rm 101, 103, 104, Run Run Shaw Building
Summer/Normal Schedule

Monday to Friday: 8:30 a.m. - 10:00 p.m.                                      
Saturday:         8:30 a.m. -  3:30 p.m.                                      
Closed on Sundays & Holidays                                                  
Summer Schedule
Monday (8:30 a.m.) - Saturday (3:30 p.m.)
Closed on Sundays & Holidays

Normal Schedule                     
Monday (8:30 a.m.) - Saturday (8:30 p.m.)
Sunday from 12:30 noon to 6:30 p.m.    
Closed on Holidays                
Holiday Schedule for April 1993

(VAX 6420, IBM 9375, DECsystem 5500s and SUN SPARCserver 670 will be running unattended on all holidays)

The Saturday preceding last Monday in August and the last Monday in August (Liberation Day)

August 28,1993 (Saturday) to August 30, 1993 (Monday)

    Computer Centre closed.               
    All terminal rooms closed.
August 31,1993 (Wed)

    Computer Centre open at 8:00 a.m.
    All computer systems resume service at 8:30 a.m.
'Help Desk' Consultation Hours

Rm 109, Run Run Shaw Building (8592480)

Monday - Friday: 9:00 a.m. - 12:30 p.m.
                 2:00 p.m. - 5:30 p.m.
Saturday:        9:00 a.m. - 12:30 p.m.
Closed on Sundays & Holidays

General News

IBM 9076 Scalable POWERparallel SP1 System

Computer Centre is currently providing central computing for supporting teaching and research in the University through its VAX 6420 VMS and several UNIX compute-servers from DEC, SUN and HP. Many research programs that run on these systems are computation-intensive. The demand for computing power is so great that soon after the systems were put into service, they have been running close to full utilization. It is not unusual that large program jobs have to wait and run for days on the existing systems. As the University is rapidly expanding its research activities, it is necessary that our expert researchers who are working on computation-intensive projects should be provided with much more computing power.

We are pleased to announce that the central computing facilities are getting a leapfrog enhancement with our recent purchase of the IBM 9076 Scalable POWERparallel 1 (SP1) system. This system has a theoretical peak performance of 1 GFLOPS (billions of floating point operations per sec). In addition to the high computational speed, the IBM 9076 SP1 system is also capable of supporting simultaneous serial and parallel computing.

Together with the 9076 SP1 host system, we have also ordered 2 high- resolution RS/6000 360 workstations for data visualization applications and several software packages to facilitate program development on the new system. More details of the new facilities are given in the following sections.

A System of Supercomputer Performance

The IBM 9076 SP1 system represents the latest technology of IBM for high-speed and parallel computing. The system we have purchased consists of 8 RS/6000 processors which are inter-connected by a high- performance switch. File storage for the system is provided by a RS/6000 570 file-server through NFS (Network File System) operations. Furthermore, a RS/6000 22W is provided as the control workstation for managing and maintaining the operation of the multiple processors of the system.

Each processor of the SP1 system can deliver a peak performance of 125 MFLOPS, and thus the 8-node system has an aggregated peak performance of 1 GFLOPS. It is about 200 times of that of the VAX 6420 system and can be considered as supercomputer performance in some sense. The SP1 system can be expanded to have a maximum of 64 processors. We expect that with this new system, the multiple-day jobs on the VAX could be run to their completion within a few hours.

Support of Parallel and Serial Processing

Parallel computing has attracted much interests in the computing industry as well as in the academic and research communities in recent years. Since parallel computing is still a relatively new subject, many of our users who have been doing researches by running serial programs might find it difficult, especially at the initial stages, to transform their problems and convert their programs to be processed in a parallel computing environment.

One of the merits of IBM 9076 SP1 system is its capability of supporting simultaneous parallel and serial, and interactive and batch processing. The seemingly conflicting requirements of the serial and parallel computing models can thus be accomplished on the same system. Our users should also find it fairly easy to convert and develop their serial programs on the SP1 system for fast processing. Moreover, the SP1 system will provide us with a parallel computing environment so that we can carry out research and development of parallel algorithms and programs for large problems.

Software Available

The IBM 9076 SP1 system will come along with the AIX operating system, an IBM version of Unix, FORTRAN and C compilers. The IBM AIX Parallel Environment will also be provided for supporting parallel program development and processing. The AIX Parallel Environment consists of the following modules:

- Parallel Application Program Interface (API): the program libraries for providing the functions of message-passing, collective communications and task management that are required for developing parallel programs.

- The Parallel Debugger: for debugging parallel programs.

- The Profiler: for analysing the execution of parallel programs. Information such as the execution time spent in each function call, invocation frequency of a function, sequence of function calls, etc., can be recorded by using the Profiler for further analysis so as to improve the program performance.

- The Performance Visualization and Monitoring Tool: a graphical user interface for providing both predefined and user-defined views of the processing events that are taking place within the application program, the Parallel Operating Environment, and the AIX kernel. By visualizing what is happening in the application program and its execution environment, program performance analysis and tuning, as well as problem isolation can be facilitated.

- The Parallel Operating Environment: a graphical user interface for setting up the parallel operating environment, and for controlling and monitoring the execution of and interactions between the parallel processes.

In addition to the IBM system software described above, a number of popular scientific computing software have been ordered. These software include the IMSL Libraries, Mathematica, MATLAB, SAS and SPSS.

Data Visualization Facilities

For computation-intensive research programs, especially when they are run on high-speed computers, it is common that huge volume of result data have to be examined. It would generally be very difficult to interpret the data if they are only presented in their native format as numeric values. Data visualization which transforms large volume of data to either static or dynamic graphics is a well-accepted approach to facilitate the interpretation of computation results and gain insight of the problems under study efficiently and effectively.

Together with the IBM 9076 SP1 host system, a cluster of IBM RS/6000 M20 and two high resolution IBM RS/6000 360 workstations have also been acquired to work with the IBM host. These workstations, particularly the two RS/6000 360's, will be equipped with appropriate software to form a group of powerful data visualization facilities for users to perform visualization of the large volume of data that would be generated by their applications.

Convenient Access through Campus Network

The IBM 9076 SP1 system will be connected to the University's FDDI/Ethernet Campus Network as one of the central compute-server nodes. All workstations in the campus can have efficient and convenient access to the system through the University Campus Network.

System Availability and User Support

At present, there are only a few pilot IBM 9076 SP1 systems installed, and the system is scheduled to be generally available in September this year. We are expecting that our system will be delivered by that time.

The new system will be primarily set up for supporting computation- intensive research projects of the University. Use of the system for student projects and instructional classes can also be arranged.

To help our users to familiar with the new system, its operation environment and potential capability so as to gain full benefits from the new facilities, Computer Centre is preparing to strengthen our support in scientific computing and to provide the necessary training and user assistance. We shall be announcing these provisions in due course.

Facility Overview

The hardware features of the new facilities and the software available are summarised below:

IBM 9076 SP1 system

No of processor nodes: 8 (max 64) Memory per processor node: 64MB (max 256MB) Disk storage per processor node: 1GB (max 2GB) Clock rate per processor node: 62.5MHz Peak performance per processor node: 125MFLOPS System Peak performance: 1GFLOPS (max 8GFLOPS) Linpack DP 1000 per processor node: 89.6MFLOPS No of integrated Ethernet adaptor 2 per processor node: High Performance Switch

Peak bandwidth per connection: 40MB/sec bi-directional Hardware latency: 500 ns RISC System/6000 570 file-server

Memory: 32MB Disk storage: 12GB Clock rate: 50MHz Peak performance: 100MFLOPS Linpack DP 1000: 73MFLOPS RISC System/6000 22W control workstation

Memory: 16MB Disk storage: 1GB Clock rate: 33MHz Linpack DP 1000: 13.9MFLOPS RS/6000 360 Visualization workstation

Memory: 64MB Disk storage: 1GB Clock rate: 50MHz Peak performance: 100MFLOPS Linpack DP 1000: 73MFLOPS RISC System/6000 M20 workstation

Memory: 16MB Disk storage: 400MB Clock rate: 33MHz Linpack DP 2000: 13.9MFLOPS Software

IBM AIX operating system IBM XL Fortran IBM XL C IBM AIX Parallel Environment IBM AIX Loadleveler IBM AIX Windows/6000 IMSL Fortran libraries MATHEMATICA MATLAB SAS (BASE, STAT, IML, FSP, AF, GRAPH) SPSS with Graphics, Table and Categories P.T.HO Tel.: 8592491 E-mail:

Account Renewal and Deletion

At present, all staff and students are eligible to have one general account on one of Computer Centre's academic host computers, namely the HKUCC, HKUXA/HKUXB, HKUSUB and HKUVM1 systems, during their stay in the University. The computer budget for the general accounts will be reset to the standard value on September 1 each year if the users remain as members of the University on that day.

Users who are leaving the University are reminded that their accounts and files on the academic host systems will be deleted. Users are thus advised to backup their useful files on tapes or diskettes well before their accounts are deleted. The account deletion arrangements are as follows:

a. All accounts and their files of the 1993 graduates will be deleted on September 1, 1993.

b. For staff and students leaving the University, their accounts will be deleted when Computer Centre receives the notices from the Registry of the University that the users are no longer on the University's staff and student lists.

c. Course accounts including Oracle course accounts and their data created for the last academic year (1992-93) will be deleted on September 1, 1993. If you have any useful files kept in these course accounts, you should transfer them to either tapes, diskettes or other backup media well before September 1, 1993.

d. Special accounts which are not renewed before August 31, 1993. The Special accounts include Departmental/group/production accounts, Consultancy accounts, and Guest accounts for visiting scholars/fellows. Users of these special accounts should have received from Computer Centre a renewal notice by now.

C.M. Mak
Tel.: 8592491

Computer Account Applications for Students

All staff and students are eligible to apply for a general computer account on one of the host computer systems operated by Computer Centre . It is our experience that there will be a very large number of applications for computer accounts from new students, especially the undergraduates, at the beginning of each academic year. During this period, users may have to wait for a week or so before their account applications are processed. In view of the fact that the number of applications has been increasing steadily in the last few years, we have to streamline the account application procedure so that the time required for application processing and account creation can be shortened.

Starting from September 1, 1993, we are adopting a new procedure for our undergraduate and postgraduate students to make their applications for general computer accounts. With the new procedure, students can conveniently apply for their general computer accounts through any PC station installed in Computer Centre . We expect the new arrangement, which will save a lot of papers otherwise required for the application forms, will shorten the time for application processing and account creation to about 3 working days. For the time being, staff users are still required to fill in the appropriate application forms and return them to Centre's General Office (Room RR- 223) for their computer account applications. However, we are also considering to extend the new account application procedure, which will be described in the following paragraphs, for staff users at a later stage. Before a student can register for a general computer account, he has to know his Student Number and Hong Kong Identity Card Number and the procedure for starting the Network-PC's in Computer Centre . (To start up a Network-PC, a Network-PC Start-up Diskette is required. This can be purchased from the laser-printer counter in Room RR-103 or from the Centre's General Office, Room RR- 223.) To register for an account, the user has to carry out the following steps at any Net_work-PC stations of Computer Centre :

  1. Login one of the Network-PCs in Computer Centre (Room RR-103).
  2. Start up the PC with the Network-PC Start-up Diskette.
  3. Select from the HKUMENU the item "Create student account on time- sharing computer"
  4. The PC will then display an account creation screen and prompt you to enter your student number and Hong Kong Identify card number.
  5. Once you confirm that the information you have entered is correct, your general account will be created in 3 working days.
If you have any comments or enquiries about this new procedure, please contact the undersigned.

C.M. Mak
Tel.: 8592491


VMS upgrade

The VAX/VMS system has been upgraded from version 5.4-2 to 5.5-2. The upgrade is transparent to most users and hence should not effect any job execution. However, if you have encountered any difficulty in using the system after the upgrade, please contact our Help Desk or the undersigned for assistance.

If you wish to find out the new features provided by VMS 5.5-2, you can issue the DCL command "HELP V55_NEWFEATURES" at the $ prompt for the information.

C.M. Mak
Tel.: 8592491

Computer Services Digest

SQL *Plus (Part II)

This is the second part of a series on introducing SQL (Structural Query Language) to our users. We have already discussed how to use the SELECT statement in the last issue of Computer News. This article is devoted to the use of Data Definition Language and Data Manipulation Language.

3. Data Definition Language (DDL) comprises of the SQL statements which affect the structure of the database objects and often involves the Data Dictionary. The Data dictionary contains information about database objects, database users and database events. The discussion on DDL is limited to those statements which are related to tables only, namely ALTER TABLE, CREATE TABLE and DROP TABLE. A table is the data structure which holds data in a relational database and it comprises of rows and columns.


It allows you to create the definition of a table, the basic structure to hold user data. You have to specify the following : table name, column names, column data types and the maximum width of each column. The Data Dictionary is updated automatically when the CREATE TABLE command is invoked.

Example: To create a table called dept with two columns, deptno and dname

     DNAME CHAR(20));
To forbid NULL values being entered in a column of a table, enter the NOT NULL clause at the end of the corresponding column information of the CREATE TABLE command.

Example: To create a table called dept with the column deptno NOT NULL

     DNAME  CHAR(20));
With execution of the above command, any attempt to add a row of data without deptno will fail and produce an error message. The rules for naming tables and columns are :

Restrictions on names

- First character must be A-Z or a-z (but stored in uppercase)

- Subsequent characters can also be numerals, the symbols of $, # or _ (commas are not allowed)

- Names can be up to 30 characters

Names must be unique

- Table name must be unique to your userid

- Must not be an ORACLE reserved words

- Column names must be unique within a table

The common data types are :

- CHAR(n) where n is the length of the data field which can be at most 240 characters

- NUMBER(n,d) where n is the total length of the numeric data field, and d is the number of decimal places

- DATE - It consists of date plus the actual time of day

- LONG - Text field which can be of a maximum size of 64 kilobytes

- RAW(n) where n is the length of the data field which can be at most 255 characters. RAW data type can only be entered and displayed in the form of hexadecimal values


It allows you to alter the definition of a table by adding columns or modifying column definitions. When a new column is first added, all of its rows are NULL.

Example: To add a new column, location, to the dept table

You can use the MODIFY clause to change any of the following attributes of a column : size, datatype and NOT NULL.

Example: To modify the column length of dname from 20 to 30

You cannot reduce column length nor change datatype unless the column is empty.


It allows you to remove the specified table and all its data from the database if you are the owner of the table.

Example. To drop the dept table.

If you have data in the table dept, it will be deleted permanently. When you drop a table, its associated indexes will also be deleted at the same time, irrespective of whether they were created by you or by other users.

4. Data Manipulation Language (DML) comprises of the SQL statements which manipulate data. We have already covered the SELECT statement in the last article, this time we would like to discuss the other three commonly used data manipulation statements, namely INSERT, UPDATE and DELETE.


It adds new rows to the specified table. When the INSERT command is used with the VALUES keyword, only one row will be added. The table specified in the command must have been created before and the values given in an INSERT command must be separated by commas. Each value must match the data type of the targeted column and all values for the data type CHAR and DATE have to be enclosed by single quotes.

Example: To insert data into the dept table

Example: To insert NULL values into the dept table
Values for selected columns of a table must be given in the same order as they are specified in the INSERT clause.

Example: To insert values into selected columns of the dept table

     VALUES ('OTHERS',60);
The INSERT command can also be used to first select values from another table and then insert them into the desirable table. This operation can be done by replacing the VAL_UES clause of an INSERT command by a SELECT clause.

Example: To insert rows into dept from another table called old_dept

     FROM OLD_DEPT WHERE DEPTNO IN (10,20,30,40);

It changes the data in the specified table.

Example. To update a field in the dept table

      WHERE DEPTNO = 10;
If the WHERE clause is omitted, all values in the column will be changed to the value as given in the SET clause.

You can update multiple columns by specifying the required changes in the SET clause.

Example. To update multiple columns in the dept table


It removes rows from a table.

Example. To remove all rows from the dept table.

If the WHERE clause is omitted, all rows are to be deleted. If the WHERE clause is specified, the rows which satisfy the condition specified in the WHERE clause are to be deleted.

Example. To remove rows from the dept table by using the WHERE clause.


S.L. Lee & K.T. Wan
Tel. 8592485 & 8597971 

Training News

Course 1/93 - Workshop on MS Windows


This workshop is to help the users who are new to MS Windows to understand its basic concepts and operations. Emphasis is placed on explaining and practising the skill you need to work with MS Windows. However, the use of specific application software run under MS Windows, e.g. MS Word for Windows, WordPerfect for Windows, etc., will not be covered.


Upon completion of this workshop, users will be able to get started working in the MS Windows environment and have the basic understanding of the following areas:

  1. Understanding of the general layout of Windows
  2. Knowledge about the various types of Windows
  3. Use of common Windows menus for actions
  4. Use of mouse for operations supported by Windows
  5. Use of Windows File Manager to perform basic DOS file operations
  6. Use of Control Panel to change the windows environment
  7. Set up Print Manager to control printers
  8. Use of Windows accessories, such as calculator, clock, notepad, etc.

  1. Windows operating environment
  2. Use of mouse
  3. Menus in the Windows
  4. Working with File Manager
  5. Control Panel
  6. Print Manager
  7. Windows Accessories
Pre-requisite:   None.

Duration:        3-hours

Course No: Title:      Date/Time                  Venue:

1/93       Workshop on Sept 14, 1993 2:00-5:00 pm Registration required.
           MS Windows  RR101, Run Run Shaw Bldg.  Max. 20 persons.
                                                  Staff Only.
                                                  Conducted in 

Please complete and return the attached Registration Form to Computer Centre . Successful applicants will be notified by telephone.

For any enquiries, please contact Miss Heti Cheng (tel.: 8592491).

Microcomputer Software Workshops

This summer, three 3-day workshops on the use of three popular software, the Lotus 123, WordPerfect and dBase IV are organised. Workshop is an effective way of providing in-depth hands-on training in the use of a software. The schedules of the workshops are:

Workshop   Title                Venue              Date

W1/93      WordPerfect for DOS  RR-201             Aug 24, 1993 (Tue)
                                Run-Run Shaw Bldg  Aug 25, 1993 (Wed)
                                                   Aug 26, 1993 (Thu)

W2/93      Lotus-123 for DOS    RR-201             Sept  1, 1993 (Wed)
                                Run Run Shaw Bldg  Sept  2, 1993 (Thu)
                                                   Sept  3, 1993 (Fri)

W3/93      dBase IV for DOS     RR-201             Sept  7, 1993 (Tue)
                                Run Run Shaw Bldg  Sept  8, 1993 (Wed)
                                                   Sept  9, 1993 (Thu)
Since the workshops are organised with an outside organisation, the C & D Computer Ltd., there will be a nominal charge of HK$350 per participant. Interested persons should read the general information below before completing the registration form and return it to Computer Centre for the course enrolment.

General information:

The workshops are aimed at providing in-depth hands-on training in the use of the software.

. There will be two sessions on each day of the workshops : from 10:00 a.m. to 1:00 p.m. and from 2:00 p.m. to 4:30 p.m.

. Registration should be made with the attached registration form on the first-come-first-serve basis.

. Registration form should be sent to Computer Centre with attention to Miss Heti Cheng (Room RR-223, Run Run Shaw Building). Registration by fax is acceptable (fax number: 559 7904).

. Enrolment is limited to staff and students of the University only, and the maximum number of participants in each workshop is 20.

. Successful applicants will be notified by telephone, and will be asked to confirm their registrations at least one working week before the workshop begins. Payment should be made in cash or cheque, or through departmental requisition (for applicants supported by department). Once accepted, the fees are not refundable. However, substitution of participants is possible by written notification to the Centre.

. For any enquiries, please contact Miss Heti Cheng (telephone number: 8592491) or contact Mr. WK Kwan (telephone number: 8597974, email:

User Services Group, Computer Centre , the University of Hong Kong