Galaksija BASIC
# Galaksija BASIC

Galaksija BASIC was the BASIC interpreter of the Galaksija build-it-yourself home computer from Yugoslavia. While being partially based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC, the extensive modifications of Galaksija BASIC—such as to include rudimentary array support, video generation code (as the CPU itself did it in absence of dedicated video circuitry) and generally improvements to the programming language—is said to have left not much more than flow-control and floating point code remaining from the original.

The core implementation of the interpreter was fully contained in the 4 KiB ROM "A" or "1". The computer's original mainboard had a reserved slot for an extension ROM "B" or "2" that added more commands and features such as a built-in Zilog Z80 assembler.

## ROM "A"/"1" symbols and keywords

The core implementation, in ROM "A" or "1", contained 3 special symbols and 32 keywords:

    begins a comment (equivalent of standard BASIC REM command)
    Equivalent of standard BASIC DATA statement
    prefix for hex numbers

### ARR$(n)

    Allocates an array of strings, like DIM, but can allocate only array with name A$

### BYTE

    serves as PEEK when used as a function (e.g. PRINT BYTE(11123)) and POKE when used as a command (e.g. BYTE 11123,123).

### CALL n

    Calls BASIC subroutine as GOSUB in most other BASICs (e.g. CALL 100+4*X)

### CHR$(n)

    converts an ASCII numeric code into a corresponding character (string)

### DOT x, y

    draws (command) or inspects (function) a pixel at given coordinates (0<=x<=63, 0<=y<=47).

### DOT *

    displays the clock or time controlled by content of Y$ variable. Not in standard ROM

### EDIT n

    causes specified program line to be edited

### ELSE

    standard part of IF-ELSE construct (Galaksija did not use THEN)

### EQ

    compare alphanumeric values X$ and Y$

### FOR

    standard FOR loop

### GOTO

    standard GOTO command

### HOME

    equivalent of standard BASIC CLS command - clears the screen

### HOME n

    protects n characters from the top of the screen from being scrolled away

### IF

    standard part of IF-ELSE construct (Galaksija did not use THEN)

### INPUT

    user entry of variable

### INT(n)

    a function that returns the greatest integer value equal to or lesser than n

### KEY(n)

    test whether a particular keyboard key is pressed

### LIST

    lists the program. Optional numeric argument specifies the first line number to begin listing with.

### MEM

    returns memory consumption data (need details here)

### NEW

    clears the current BASIC program

### NEW n

    clears BASIC program and moves beginning of BASIC area

### NEXT

    standard terminator of FOR loop

### OLD

    loads a program from tape

### OLD n

    loads program to different address

### PTR

    Returns address of the variable

### PRINT

    Printing numeric or string expression.

### RETURN

    Return from BASIC subroutine

### RND

    function (takes no arguments) that returns a random number between 0 and 1.

### RUN

    runs (executes) BASIC program. Optional numeric argument specifies the line number to begin execution with.

### SAVE

    saves a program to tape. Optional two arguments specify memory range to be saved (need details here).

### STEP

    standard part of FOR loop

### STOP

    stops execution of BASIC program

### TAKE

    replacement for READ and RESTORE. If the parameter is variable name, acts as READ, if it is number, acts as RESTORE

### UNDOT x, y

    "undraws" (resets) at specified coordinates (see DOT)

### UNDOT *

    Stops the clock, not part of ROM

### USR

    Calls machine code subroutine

### WORD

    Double byte PEEK and POKE

## ROM "B"/"2" additional symbols and keywords

The extended BASIC features, in ROM "B" or "2", contained one extra reserved symbol and 22 extra keywords:

* /LABEL
* ABS(x)
* ARCTG(x)
* COS(x) COSD(x)
* DEL
* DUMP
* EXP(x)
* INP(x)
* LDUMP
* LLIST
* LN(x)
* LPRINT
* OUT
* PI
* POW(x,y)
* REN
* SIN(x), SIND(x)
* SQR(x)
* TG(x) TGD(x)
