- Email: [email protected]
CAI system for basic
North-Holland Microprocessingand Microprogramming 12 (1983) 227-230
227
CAI System for Basic Du Chang Zheng Electronic Engineering Department, Software Division Xi'an Jiao-Tong University, Xi'an Shannxi, China T h i s paper presents a BCA system (BASIC's CAI system with APL). APL (A P r o g r a m m i n g language) is widely used in nonumerical application. The work delineated in the paper is only a reaserch on CAI system with a microprocessor. By m e a n s of the BCA system~ a student may learn BASIC by himself and test whether he u n d e r s t a n d s it. The BCA system can also evaluate his result in time. according to the student's learning state. The paper pointed out some problems about designing a CAI system in a mieroprocessor. In order the extend the function of the m i e r o p r o c e s s o r and make the student's learning more suitable for person's r e a l i z a t i o n law, the BCA system supports a way by which a multiuser can crose-serial uses the BCA system with only one microprocessor.
I.
INTRODUCTION
CAI has some characteristics, as follows: -- CAI is more ingenious and more perfect than other m o d e r n I n s t r u c t i o n methods. -- CAI has changed the traditional instrucation methods. It can gave different progress with different students. -- Intellectual analogy could supply rich perceptual knowlogy. For example, active state of programming are displaied. The CAI system with a m i c r o p r o c e s s o r has some adventage as follows: -- The structure of a system is ingenious. Needn't use special language as a tool. -- The cost is the lowest in various CAI systems. The following points are given in consideration of designing the whole structure: -- Storage capacity. The m i c r o p r o c e s s o r storage Capacity used in the CAI system has directly relation with the schedule of teaching modulears. To the microprocessor having different storage capacity~ we should consider the relation between time and space correctly. -- Utility. The rate of teaching program can be c o n t r o l l e d entirely by students without interferce by the system programer. The matliuser can share this system. -- The stepwise refinement should be adoped in the programming. Every teaching module should be p r o c e s s e d by the way of hierarchy.
a common ASCII k e y b o a r d instead of an APL keyboard. So the following APL character set in program are written by the mremonic code. The whole structure is as follows:
sketch
of the BCA system
- -
The BCA system is supported by RT-11 operating system,it consists of a software package with APL. It is running in ADROMEDA11/B made in U.S.A. In the APL state, AWS (Active Work Space) is limited as 11889B, less than 12KB. The m i c r o p r o c e s s e r has two floppy disks with a single side and single density (512XB x 2), with a general CRT and
2.
THE REASON
OF USING
APL AS TEACHING
TOOL
In an interactive system the courseware (course teaching ware) of CAI system can be written by various languages. The size of the whole courseware is very important in designing the CAI system. In the microprocessor which is one of key contradictories. APL is a very concise programming language especially suitable for handling numeric and character a r r a y - s t r u c t u r e d data. APL allows u s e r - d e f i n e d functions to be expressed with the same syntax as that used to express primitive language functions. T h i s provides the user with an efficient and simple means of expanding the capabilities of the language to handle the requirements of any application area. This is very importent for writing the CAI courseware on the m i c r o p r o c e s s o r whose memory is limited.
D.C. Zheng/ CA/System for BASIC
228
Second, APL language has powerful communication function in the interative system. Not only can it display some compiler information of the APL system, but also add some information to the CAI system to deal with. these features are useful for compilering, debugging the CAI sourseware and controlling the program flow. Third, APL-11 has two kinds of file systems. In APL-11 environment, the file system command (for example, the command exchanging internal-memory and exteral-memory) can be written into the self-defined function as a character string of APL. Using the function deals with character string, this file system command can be controlled and excuted at some proper times. Thus a closed CAI system is formed. For some deailted materials about APL-11 language please consult the historial document listed at the end of this paper. 3.
SOME CONCRETE PROBLEMS THIS SYSTEM
I)
Storing and Scheduling
ABOUT REALIZING
According to the hardware environment mentioned above we can find that it is improbable to store all colossal courseware of CAI in the memory which is only less than 12KB at the same time. And sometimes even a whole teaching module can not be stored at the same time in the 12KB memory. The problem about scheduling the CAI courseware must to be solved, because the teaching sequence might be different for different students and students might also send courseware to learn by himself regardless of the attention of the BCA system. The BCA system used the "Roll in-Roll out" algorithm similar to that in operating system to solve above problem. After the BCA system's turned on, it schedule the control program into memory and excute it by itself. When students select a lesson to learn or the system sugguests students a lesson to learn, the control program of the CAI system excutes a APL system command that is formed according to the information inputed by students to schedule the teaching module about the lesson into the AWS by itself. At this time, what is stored in the AWS is only the control program and the ralativing teaching module. If the relating lesson itself is also very large, we can divide this module into some sub-modules and u s e h i e r a r c h y scheduling algorithm, which schedules the sub-moduler in or out AWS in sequence according to the need of students.
Because APL-11 system does not have the command that can extend the length of the symbol table, the length is also limited as 78OB. To prevent the symbol table from overflowing the system uses the following methods: -- Assign all variable and procedure names in hierarchical way, so as to avoid using much extra diffrent name symbols. Since the APL provides the dynamical localijing feature, the use of the same name symbol in different layers cannot caure confussion. -- Since the APL-11 assigns a longer symbol table for a longer length symbol, the length of all variable and procedure names is strickly controlled. -- Since the statement number is regarded as a kind of symbol name in APL, after testing of each module the statement number is used instead of the statement label. All coursewares of the BCA system are stored in the disk in the form of files and every teaching modules are stored by the name of the main module. So that according to input message of students the BCA system can analyse and process easily. In some processes, the BCA system uses the method with more time spent to gain extra space. It is recommendful method to the interactive CAI system based on the microprocesser. 2) Cross using for the multuser on a single computer.to leavning language is not a short process. It is also impossible to let the student learn over all lessons during a continuing periodo After a period of learning, the student must have a time to rest and understand what he has learnt. Considering the students at different levels, the whole learning process can not be reduced to several hours. During the long learning process, a student might interrupt. So he has to resign the computer source. In order to use the computer software and the CAI courseware efficiantly the BCA system provides '~cross-using of the multuser on a single terminal and computer" method. By using the method, a student might interrupt after a period of learning, then another student could do. The BCA system will remind the student of where to go on and record the time with APL-I beam function at present when the student starts the reentry. The maximum number of the students in the system can be 10. When there are more than 10 students to use the BCA system, (FIFO) '~first-in first-out '~ method will be usedfinding out the longest interruping student and deleting it (if the user uses the BCA system again, the control program will display the reason for deletion), then putting the latest user into the BCA system.
D.C. Zheng / CAI System for BASIC
T h i s is realized using two tables: student name table (10 15) and learning i n f o r m a t i o n table (10 9).
-- pointing
The following's the control program ZC, it includes the scheduling of all teaching m o d u l e s and realizing of the above method, 3)
Organization
of Q u e s t i o n
Base
(OB)
In this system there are some organizing m e t h o d s of question for students to learn. The system uses the following types: -- F i x e d Question Base, selecting fixedly. It is basic for some c o n c e p t i o n questions. -- F i x e d Question Base, random choice. It is usually the question on which students often make mistakes. -- P r o d u c i n g Question Randomly I it is mainly use for p r e v e n t i o n from "inertia of learning". It makes students to be active, thinking from beginning to end. Selecting the following ways for teaching -- display some new concepts and explain some problems -- multiple choice answer -- fill into the blanks with words~ figures or some BASIC statements
229
out m i s t a k e s
and correcting
G e n e r a l l y speaking, the CAI system would prepare a lot of questions. B e s i d e s it, there are also a lot of conceptions, illustrations, tables and graphs, etc. That will be displayed on the screen for the students. They have a high frequently for input and output. The BCA system put them on the flopp disk by the random file format. When needed, these m e s s a g e s may be read immediately. Except common i n f o r m a t i o n (for example: matrix for Chinese words), the other i n f o r m a t i o n of random file is also divided by teaching modules. For the general purpose, we just need to change its contexts, but don't revise the c o n s t r u c t i o n of teaching modules. T h e n the teaching module might be used for another course examination. For example: E n g l i s h Test. 4)
Intellectual
analogy
The microprocessor CAI system often acceptes the way of the initiative asking questions for a teaching progress. It makes the processing coursware more easily. When the students answer all of the questions
ZC program
[1] [2] [3] [4] [5] 116] [7] [8] [9] [ :10] [ 1:1.] [ :1.2] [ 1::-: ] I: 14]
[15] I: :1,6]
[17] [ 1:3] [IC~] I: 2 0 ] [21] iZ 22
]
[23] [24] [25] I_'26] [27] i:28]
[2.9,] [ :30 ] [31] [ :32 ] [33] [34] [:_--:5] I: :-:6. ] [37] [ :::8 ] [39] [ 40 ] [41] [42] [43] I:4 4 ]
. D L ZC ;A;B~C~D;E;',EI;T~ I~.J~i<~G;Bg~ IA~L7~LE: S_O,0.RO.BX_5 40.RO2. IQ[31200,0.RO2.PTI726. L7_'1234567890,O.ROL:B_'QWERTYUIQPLK.JHGFDSAZXCVBNM • GO( " Y " = I " A _ . Qi'-_.!).16, . E P " C I N P 5""
,.Ep, 1 g! 107
• G O ( ' C " = I " A ) / 4 4
• GEt( " N " = I ' ' A ) / 2 llZl:=: i~
4:1.0
518 Q 120 CINP 5,.EF"638
Q 91. • GQ((+/NT&.=IA)=1)/16,0.ROIA_'TJ"(IA_.QQ),8.RO ...... • GO("Y=I. A_.Og!)/12,.EPCINP 5,0.RO.BX_ARE Yi3U A B E G I N E R .GO2,.EP"729 g! 1 0 1 ' • GO(ZL<'5)/15 A _ R T [ ~ 9 ] . I O . F L / [ 1 ] R T [ -~9 ' ] . GO1'-?, 0 . R O R T [ A ; ] _ ( ' l , O. R O N T [ A ; ] _ I A , ' . 3 . RO .GOIS,0.RONT[ZL-~ ]_IA,8.RO" ",O.ROZL_ZL+I • GEt('Y =L"A_.i2Q)11.8, .EP'CINP 5",.EP :-::30 g,~ 5 : 3 " • GO20,0.ROI_RT[(NT&.=IA).IQl~ ].I00 RT[ (NT&. =IA). I01..~ ] _ 0 I_l RT[ (NT&. =IA). IIZil-~ 9 ] _ . I B 2 A
883
":'
¢! 2 6 2
• tz~o("N'=I"A-.L.]Q)/26,.EP CII~P 5 , . E P I 1 4 5
Q 6.1
CINP 5,.EP'1206 Q 51",.EF' ) R E A D D X I : K N " K N . E P A _ . L-]Q . G022, . EP' ) E R A S E K N CINF' 15, 0. RQ. B X _ " Y O U S H O U L D LI-ARN L E S S O N ", . E N I BgL"CJ',A_.Qg!,.EP'CINP 5",.EP'1257 Q 52" EP'CINP I O , O . R O . BX_. IB3:B,O. R O . . B X _ . I B I 7 EF'Bg,.EP' ) R E A D D X I : " , B 9 EP")ERASE ",Bg,0.RORT[(NT&.=IA), IOI;.EPA]_S GO( ( + / ( R T [ (NT&. = I A ) . IOI ;. IO 7]). I 0 0 ) = 0 ) / 3 5 GO( " Y = I ' A _ . QQ) 134, 0. RQ. B X _ ' W O U L D Y O U L I K E H A V E R E S T GO22,0.ROI_RT[(NT&.=IA). IOl; ]. I00 G O 2 , 0 . RO. B X _ " S E E Y O U L A T E R , B Y E - B Y E ! B_(O. O 2 5 # ( + / R T [ ( N T & . = I A ) . IOI;. I 0 6 ] ) ) •G O ( B > 7 0 ) / 3 9 , 0 . R O B _ ( ( + I R T [ ( N T & . = I A ) . I0:1 ; 7 : 3 ] ) # 0 . 4 2 5 ) + B 1 3 0 9 Q .'37 •G O 2 , 0 . R O R T [ ( N T & . = I A ) . I O I ; ]_() R T [ ( N T & . = I A ) . IOl~ ] _ 0 , . E P " 1 3 9 6 Q 40" Z L _ Z L - I , 0. R O B _ ( N T & . =IA). IOI RT[B;]_RT[ZL~ ],O.RONT[B~]_NT[ZL; ] NTEZL;]_"
",O.RORTEZL;]_O,0.ROIA_9.
•GO2,0.RO.BX_'"CAI" . E P " ) S A V E DXO: ZC" .DL
WISH
YOU
them
RO"
SUCC:ESS
"
'"
? AN',siWER.
230
D.C. Zheng / CAI System for BASIC
correctly, they are considered to have mastered the conception basics!ly. To gain the above object, it needs the following points: -- the courseware designer must have some experiences. -- designed questions must summarize involved conceptions. To precesse above condition better is not easily. Just as dayly teaching, new concept will cause various questions that students have. For this reason, the BCA system designed some reply programs. Using them students might ask some questions by certain formats. According to the information the BCA system will display the following feedback messages: -- for the question judgment (for example: is it correct?). -- if not correct, point out some errors. -- would you go on to put out questions. The reply programs in every teaching module look like the sytax recognizer. The BCA system provides a program that is used to recognize expression syntax and analogy excution (if the expression is right). It is derided as three steps. That is, roughexamming syntax,careful exammlng and interpretation excution. In order to make students understand excuting states of the BASIC expression, the system will give out some middle results.
4.
Conclusion
A highly interactive language as APL is very suitable to realize CAI system with the microprocessor. If using a better CRT, teaching influence will be vivider and more interesting. The student may be influenced more deeply. In CHINA there is a special problem of CRT and keyboard. That is, a general CRT and keyboard has no Chinese words. A lot of research has been done on it. A larger keyboard and higher CRT have been turned out but it was too expensive. The simple way of solving the problem was to use the visual system by means of a type recorder. Because hardware requirements were limited. The BCA system only comprised some Aural-Visual experiments. We hope to do some further research on this research later.
REFERENCE (I) Oder No. DEC-II-LAPLA-A-D "APL-11 Programmer's Reference Manual" (2) Geller Freedman "Structured programming in APL"
227
CAI System for Basic Du Chang Zheng Electronic Engineering Department, Software Division Xi'an Jiao-Tong University, Xi'an Shannxi, China T h i s paper presents a BCA system (BASIC's CAI system with APL). APL (A P r o g r a m m i n g language) is widely used in nonumerical application. The work delineated in the paper is only a reaserch on CAI system with a microprocessor. By m e a n s of the BCA system~ a student may learn BASIC by himself and test whether he u n d e r s t a n d s it. The BCA system can also evaluate his result in time. according to the student's learning state. The paper pointed out some problems about designing a CAI system in a mieroprocessor. In order the extend the function of the m i e r o p r o c e s s o r and make the student's learning more suitable for person's r e a l i z a t i o n law, the BCA system supports a way by which a multiuser can crose-serial uses the BCA system with only one microprocessor.
I.
INTRODUCTION
CAI has some characteristics, as follows: -- CAI is more ingenious and more perfect than other m o d e r n I n s t r u c t i o n methods. -- CAI has changed the traditional instrucation methods. It can gave different progress with different students. -- Intellectual analogy could supply rich perceptual knowlogy. For example, active state of programming are displaied. The CAI system with a m i c r o p r o c e s s o r has some adventage as follows: -- The structure of a system is ingenious. Needn't use special language as a tool. -- The cost is the lowest in various CAI systems. The following points are given in consideration of designing the whole structure: -- Storage capacity. The m i c r o p r o c e s s o r storage Capacity used in the CAI system has directly relation with the schedule of teaching modulears. To the microprocessor having different storage capacity~ we should consider the relation between time and space correctly. -- Utility. The rate of teaching program can be c o n t r o l l e d entirely by students without interferce by the system programer. The matliuser can share this system. -- The stepwise refinement should be adoped in the programming. Every teaching module should be p r o c e s s e d by the way of hierarchy.
a common ASCII k e y b o a r d instead of an APL keyboard. So the following APL character set in program are written by the mremonic code. The whole structure is as follows:
sketch
of the BCA system
- -
The BCA system is supported by RT-11 operating system,it consists of a software package with APL. It is running in ADROMEDA11/B made in U.S.A. In the APL state, AWS (Active Work Space) is limited as 11889B, less than 12KB. The m i c r o p r o c e s s e r has two floppy disks with a single side and single density (512XB x 2), with a general CRT and
2.
THE REASON
OF USING
APL AS TEACHING
TOOL
In an interactive system the courseware (course teaching ware) of CAI system can be written by various languages. The size of the whole courseware is very important in designing the CAI system. In the microprocessor which is one of key contradictories. APL is a very concise programming language especially suitable for handling numeric and character a r r a y - s t r u c t u r e d data. APL allows u s e r - d e f i n e d functions to be expressed with the same syntax as that used to express primitive language functions. T h i s provides the user with an efficient and simple means of expanding the capabilities of the language to handle the requirements of any application area. This is very importent for writing the CAI courseware on the m i c r o p r o c e s s o r whose memory is limited.
D.C. Zheng/ CA/System for BASIC
228
Second, APL language has powerful communication function in the interative system. Not only can it display some compiler information of the APL system, but also add some information to the CAI system to deal with. these features are useful for compilering, debugging the CAI sourseware and controlling the program flow. Third, APL-11 has two kinds of file systems. In APL-11 environment, the file system command (for example, the command exchanging internal-memory and exteral-memory) can be written into the self-defined function as a character string of APL. Using the function deals with character string, this file system command can be controlled and excuted at some proper times. Thus a closed CAI system is formed. For some deailted materials about APL-11 language please consult the historial document listed at the end of this paper. 3.
SOME CONCRETE PROBLEMS THIS SYSTEM
I)
Storing and Scheduling
ABOUT REALIZING
According to the hardware environment mentioned above we can find that it is improbable to store all colossal courseware of CAI in the memory which is only less than 12KB at the same time. And sometimes even a whole teaching module can not be stored at the same time in the 12KB memory. The problem about scheduling the CAI courseware must to be solved, because the teaching sequence might be different for different students and students might also send courseware to learn by himself regardless of the attention of the BCA system. The BCA system used the "Roll in-Roll out" algorithm similar to that in operating system to solve above problem. After the BCA system's turned on, it schedule the control program into memory and excute it by itself. When students select a lesson to learn or the system sugguests students a lesson to learn, the control program of the CAI system excutes a APL system command that is formed according to the information inputed by students to schedule the teaching module about the lesson into the AWS by itself. At this time, what is stored in the AWS is only the control program and the ralativing teaching module. If the relating lesson itself is also very large, we can divide this module into some sub-modules and u s e h i e r a r c h y scheduling algorithm, which schedules the sub-moduler in or out AWS in sequence according to the need of students.
Because APL-11 system does not have the command that can extend the length of the symbol table, the length is also limited as 78OB. To prevent the symbol table from overflowing the system uses the following methods: -- Assign all variable and procedure names in hierarchical way, so as to avoid using much extra diffrent name symbols. Since the APL provides the dynamical localijing feature, the use of the same name symbol in different layers cannot caure confussion. -- Since the APL-11 assigns a longer symbol table for a longer length symbol, the length of all variable and procedure names is strickly controlled. -- Since the statement number is regarded as a kind of symbol name in APL, after testing of each module the statement number is used instead of the statement label. All coursewares of the BCA system are stored in the disk in the form of files and every teaching modules are stored by the name of the main module. So that according to input message of students the BCA system can analyse and process easily. In some processes, the BCA system uses the method with more time spent to gain extra space. It is recommendful method to the interactive CAI system based on the microprocesser. 2) Cross using for the multuser on a single computer.to leavning language is not a short process. It is also impossible to let the student learn over all lessons during a continuing periodo After a period of learning, the student must have a time to rest and understand what he has learnt. Considering the students at different levels, the whole learning process can not be reduced to several hours. During the long learning process, a student might interrupt. So he has to resign the computer source. In order to use the computer software and the CAI courseware efficiantly the BCA system provides '~cross-using of the multuser on a single terminal and computer" method. By using the method, a student might interrupt after a period of learning, then another student could do. The BCA system will remind the student of where to go on and record the time with APL-I beam function at present when the student starts the reentry. The maximum number of the students in the system can be 10. When there are more than 10 students to use the BCA system, (FIFO) '~first-in first-out '~ method will be usedfinding out the longest interruping student and deleting it (if the user uses the BCA system again, the control program will display the reason for deletion), then putting the latest user into the BCA system.
D.C. Zheng / CAI System for BASIC
T h i s is realized using two tables: student name table (10 15) and learning i n f o r m a t i o n table (10 9).
-- pointing
The following's the control program ZC, it includes the scheduling of all teaching m o d u l e s and realizing of the above method, 3)
Organization
of Q u e s t i o n
Base
(OB)
In this system there are some organizing m e t h o d s of question for students to learn. The system uses the following types: -- F i x e d Question Base, selecting fixedly. It is basic for some c o n c e p t i o n questions. -- F i x e d Question Base, random choice. It is usually the question on which students often make mistakes. -- P r o d u c i n g Question Randomly I it is mainly use for p r e v e n t i o n from "inertia of learning". It makes students to be active, thinking from beginning to end. Selecting the following ways for teaching -- display some new concepts and explain some problems -- multiple choice answer -- fill into the blanks with words~ figures or some BASIC statements
229
out m i s t a k e s
and correcting
G e n e r a l l y speaking, the CAI system would prepare a lot of questions. B e s i d e s it, there are also a lot of conceptions, illustrations, tables and graphs, etc. That will be displayed on the screen for the students. They have a high frequently for input and output. The BCA system put them on the flopp disk by the random file format. When needed, these m e s s a g e s may be read immediately. Except common i n f o r m a t i o n (for example: matrix for Chinese words), the other i n f o r m a t i o n of random file is also divided by teaching modules. For the general purpose, we just need to change its contexts, but don't revise the c o n s t r u c t i o n of teaching modules. T h e n the teaching module might be used for another course examination. For example: E n g l i s h Test. 4)
Intellectual
analogy
The microprocessor CAI system often acceptes the way of the initiative asking questions for a teaching progress. It makes the processing coursware more easily. When the students answer all of the questions
ZC program
[1] [2] [3] [4] [5] 116] [7] [8] [9] [ :10] [ 1:1.] [ :1.2] [ 1::-: ] I: 14]
[15] I: :1,6]
[17] [ 1:3] [IC~] I: 2 0 ] [21] iZ 22
]
[23] [24] [25] I_'26] [27] i:28]
[2.9,] [ :30 ] [31] [ :32 ] [33] [34] [:_--:5] I: :-:6. ] [37] [ :::8 ] [39] [ 40 ] [41] [42] [43] I:4 4 ]
. D L ZC ;A;B~C~D;E;',EI;T~ I~.J~i<~G;Bg~ IA~L7~LE: S_O,0.RO.BX_5 40.RO2. IQ[31200,0.RO2.PTI726. L7_'1234567890,O.ROL:B_'QWERTYUIQPLK.JHGFDSAZXCVBNM • GO( " Y " = I " A _ . Qi'-_.!).16, . E P " C I N P 5""
,.Ep, 1 g! 107
• G O ( ' C " = I " A ) / 4 4
• GEt( " N " = I ' ' A ) / 2 llZl:=: i~
4:1.0
518 Q 120 CINP 5,.EF"638
Q 91. • GQ((+/NT&.=IA)=1)/16,0.ROIA_'TJ"(IA_.QQ),8.RO ...... • GO("Y=I. A_.Og!)/12,.EPCINP 5,0.RO.BX_ARE Yi3U A B E G I N E R .GO2,.EP"729 g! 1 0 1 ' • GO(ZL<'5)/15 A _ R T [ ~ 9 ] . I O . F L / [ 1 ] R T [ -~9 ' ] . GO1'-?, 0 . R O R T [ A ; ] _ ( ' l , O. R O N T [ A ; ] _ I A , ' . 3 . RO .GOIS,0.RONT[ZL-~ ]_IA,8.RO" ",O.ROZL_ZL+I • GEt('Y =L"A_.i2Q)11.8, .EP'CINP 5",.EP :-::30 g,~ 5 : 3 " • GO20,0.ROI_RT[(NT&.=IA).IQl~ ].I00 RT[ (NT&. =IA). I01..~ ] _ 0 I_l RT[ (NT&. =IA). IIZil-~ 9 ] _ . I B 2 A
883
":'
¢! 2 6 2
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D.C. Zheng / CAI System for BASIC
correctly, they are considered to have mastered the conception basics!ly. To gain the above object, it needs the following points: -- the courseware designer must have some experiences. -- designed questions must summarize involved conceptions. To precesse above condition better is not easily. Just as dayly teaching, new concept will cause various questions that students have. For this reason, the BCA system designed some reply programs. Using them students might ask some questions by certain formats. According to the information the BCA system will display the following feedback messages: -- for the question judgment (for example: is it correct?). -- if not correct, point out some errors. -- would you go on to put out questions. The reply programs in every teaching module look like the sytax recognizer. The BCA system provides a program that is used to recognize expression syntax and analogy excution (if the expression is right). It is derided as three steps. That is, roughexamming syntax,careful exammlng and interpretation excution. In order to make students understand excuting states of the BASIC expression, the system will give out some middle results.
4.
Conclusion
A highly interactive language as APL is very suitable to realize CAI system with the microprocessor. If using a better CRT, teaching influence will be vivider and more interesting. The student may be influenced more deeply. In CHINA there is a special problem of CRT and keyboard. That is, a general CRT and keyboard has no Chinese words. A lot of research has been done on it. A larger keyboard and higher CRT have been turned out but it was too expensive. The simple way of solving the problem was to use the visual system by means of a type recorder. Because hardware requirements were limited. The BCA system only comprised some Aural-Visual experiments. We hope to do some further research on this research later.
REFERENCE (I) Oder No. DEC-II-LAPLA-A-D "APL-11 Programmer's Reference Manual" (2) Geller Freedman "Structured programming in APL"