Hello

BALSYS Tutor

By NightBird

Hello!

This is a very basic step-by-step example, for a simple BalSys application, or rather a game. At any time you don't understand something, please consult the BalSYS documentation, it's very thoroughly written.

The rules are simple, you surely know them; the computer thinks of a number between a given range, and you have to guess what the number could be.

1) Fire up BalSys, and think over what we need.

- In this example, we'll use Register #0 only as a temporary register, as all data generated by commands is stored there, and we don't want our stored values overwritten by accident.

Each Register takes away 8 bytes.

- So we need a Register #1 for the random number generated by the computer.

- We need Register #2 to store the number user enters.

- We have 3 registers each taking 8 bytes, and 8*3=24, so we need 24 bytes to store all variables we need, and that means, we can begin the code at .24

- We will have a greeting message, used at the beginning of the program. Its text data will reside at address marked by a Label: -> LAB 1

- We will also have a query for the tip from the user -> Text will be at Label 2

- There are 3 messages for the values entered (equal,bigger,less) -> Texts will be at Labels 3, 4, 5

- The end message -> Text will be at Label 6

2) Go into service mode, by pressing CBM-S (Control-S if PC’ keyboard).

If you don’t see on screen the monitor-panel with counters, please hit .SET [RETURN] then N then [ESC], only once, then the setting will be stored in Preferences.

Remember, that you have two counters; a Program Counter (PC) and a Service Counter (SP). With the Program Counter you can edit/view the execution addresses points of the program, and with the Service Counter you can edit the program itself. Now we begin with setting the Service Counter.
Enter the following:

.TSP 24 ; above, we determined that we need 24 bytes for variables

; and now we Transfer Service Pointer to address .24

LAB 255 ; each program must begin with this statement

LAB 100 ; This is the label for the printing out of the greeting message area,

; its value is free to choose, just watch that the values do not conflict,

; but BalSYS will notify you if this happens. Under this label, we put

; the code to print out our message. We need this Label if the user wants

; to play again, this marks the actual beginning of the executable program

PA 3,1 ; Print out a string from Label 1 until $00 is reached

/I have thought of a number

between 0 and 100/

RAND 100 ; Generate a random number between 0 and 100, in Register #0

LR 1,0 ; Copy the value of Register #0 into Register #1; this is our random number

LAB 110 ; This is the label, for printing out the user query

PA 3,2 ; Print out a string from Label 2 until $00 is reached

/Your guess?/

K 3,0 ; This is the user input, you are allowed to input 3 decimal cyphers, the

; values are stored in Register #0, as previously discussed

LR 2,0 ; Now we move the user input from Register #0 in Register #2

CR 1,2 ; We Compare Registers #1 and #2. This command returns 3 possible values,

; that can be processed later in correlation with Branch commands

; 0=EQUAL,1=LESS,2=BIGGER

B0 120 ; If Register #1 is EQUAL Register #2, jump to Label 120

B1 130 ; If Register #1 is LESS than Register #2, jump to Label 130

B2 140 ; If Register #1 is BIGGER than Register #2, jump to Label 140

LAB 120 ; Label for EQUAL HANDLING

PA 3,3 ; Print out a string from Label 3 until $00 is reached

/You have tipped right

Another game?/

KAC 2 ; This command takes only a single character without echoing, and we

; store this character in address aimed by Pointer 2 (.0 at this moment)

CBI 2,'59' ; We compare Register #2, with the ASCII hex value 59 ('y'), to see whether

; the user wants to play another game

B0 100 ; Is the value entered $59 ('y')? Then jump to Label 100-> restart

WAIT ; Otherwise, halt process, so the user can exit, or go to service mode

LAB 130 ; Label for LESS HANDLING

PA 3,4 ; Print out a string from Label 4 until $00 is reached

/The number is less/

B 110 ; Unconditional jump to Label 110->query

LAB 140 ; Label for BIGGER HANDLING

PA 3,5 ; Print out a string from Label until $00 is reached

/The number is bigger/

B 110 ; Unconditional jump to Label 110->query

Now we can enter Labels 1...5 data in the remaining memory area.

Be advised, that Labels (as per all other mnemonics) can only be entered on EVEN addresses, so whenever you finish entering data, please check that the counter is on an even number. If it is not, relocate it to the next available even number by using .TSP xxx!

In our example .DCX 00 could actually be left out as it is followed by another Label and BalSYS automatically ends the previous Label there, but just to be on the safe side we use .DCX 00 to signal the end of the printable string area for the PA 3,x command.

LAB 1 ; Label for greeting string

.DCX 93 ; Enter a hex value of $93 into memory to clear the screen ($93=CLS)

.DCC I thought of a number ; Enter string

.DCX 0D ; Enter a hex value of $0D into memory to line feed ($0D=new line)

.DCC between 0 and 100 ; Enter string

.DCX 0D00 ; New Line ($0D), and value of $00 into memory to signal end of print data

LAB 2 ; Label for user query

.DCX 0D ; New Line

.DCC Your guess? ; Enter string

.DCX 0D00 ; New Line; End of string (flag for PA 3,xxx mnemonic)

LAB 3 ; Label for EQUAL MESSAGE

.DCX 0D ; New Line

.DCC You tipped right ; Enter string

.DCX 0D ; New Line

.DCC Another game? ; Enter string

.DCX 00 ; Enter a hex value of $00 into memory to signal end of print data

LAB 4 ; Label for LESS MESSAGE

.DCX 0D ; New Line

.DCC The number is less ; Enter string

.DCX 00 ; Enter a hex value of $00 into memory to signal end of print data

LAB 5 ; Label for BIGGER MESSAGE

.DCX 0D ; New Line

.DCC The number is bigger ; Enter string

.DCC 00 ; Enter a hex value of $00 into memory to signal end of print data

3) We used PA 3,X in the example above, but that is not a standard BAL command. If you would like to stick to the original language, this would be the way to print a text from a Label area; BalSYS uses two separate pointers, they can be set to a Label area by the command TL, then you use either PA 1, or PA 2 (depending on which pointer you use), and specify how many characters to be printed out:

TL 1,101 ; Pointer 1 is Transfered to Label 101. Label 101 is where our message is

; stored.
PA 1,39 ; We print 39 characters (alphanumerical or even control characters) from the area pointed to by Pointer 1.

4) If you are interested, you can now simply write a routine that asks for the range of random numbers generated, or you can ’mask’ the generated random number, so that one peeking Registers (.SET, R) has a harder time guessing the value.

PSEUDO COMMANDS:

Name

Operand

Description

Range

.TSP

xxxx

Transfers SC to address xxxx

xxx=0…4095

.DCX

xxxx…

Writes in memory the hex string xxxx…

Lenght of xxx: 2 …16 hex

.DCC

xxx…

Writes on memory the alpha-numerical string xxxxxx….

Lenght of xxxx…: 1… 255

BAL MNEMONICS:

Name

Ope-rands

Description

Range

Oper. 1

Range

Oper. 2

Resulting

Condition

code

LAB

nnn

Set a Label point inside a program

0…255

PA

x,nnn

x=0: Reserved for future (now the same as x=1)

x=1 or x=2: Print nnn+1 characters from memory addressed by Pointer x

x=3: Print a string located at LABEL nnn, of any lenght, until a $00 value is met

1…2

1…255

RAND

nnn

Generate a random value, between 0 and nnn, on Register# 0

0…255

LR

x,y

0…15

nn,k

Input a positive value and store it onto Register#0 (nn=max number of cyphers of which k are decimal)

0…15

0…3

Key S0 (Enter)

Key S1

Key S2

Key S3,

S5, or S6

CR

x,y

Compare Register x with Register y

0…15

Res.=0

Res.<0

Res.>0

B*

nnn

Branch to label nnn if Condition=*

0…255

KAC

Input an alphanumerical character and store it onto memory addressed by Pointer n( (without echo on screen)

1…2

CBI

x,’hh’

Compare the byte addressed by Pointer x with hex value ‘hh’

1…2

00…FF

Mem=’hh’

Mem<‘hh’

Mem>‘hh’

TL

x,nnn

Pointer x = Label nnn

1…2

0…255