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 numbersARR$(n) - Allocates an array of strings, like DIM, but can allocate only array with name A$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 ROMEDIT n causes specified program line to be editedELSE standard part of IF-ELSE construct (Galaksija did not use THEN)EQ - compare alphanumeric values X$ and Y$FOR standard FOR loopGOTO standard GOTO commandHOME equivalent of standard BASIC CLS command - clears the screenHOME n protects n characters from the top of the screen from being scrolled awayIF standard part of IF-ELSE construct (Galaksija did not use THEN)INPUT user entry of variableINT(n) a function that returns the greatest integer value equal to or lesser than nKEY(n) test whether a particular keyboard key is pressedLIST 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 programNEW n - clears BASIC program and moves beginning of BASIC areaNEXT - standard terminator of FOR loopOLD - loads a program from tapeOLD n - loads program to different addressPTR - Returns address of the variablePRINT - Printing numeric or string expression.RETURN - Return from BASIC subroutineRND - 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 loopSTOP stops execution of BASIC programTAKE - replacement for READ and RESTORE. If the parameter is variable name, acts as READ, if it is number, acts as RESTOREUNDOT x, y "undraws" (resets) at specified coordinates (see DOT)UNDOT * - Stops the clock, not part of ROMUSR - Calls machine code subroutineWORD - Double byte PEEK and POKEROM "B"/"2" additional symbols and keywords
The extended BASIC features, in ROM "B" or "2", contained one extra reserved symbol and 22 extra keywords:
%/LABELABS(x)ARCTG(x)COS(x), COSD(x)DELDUMPEXP(x)INP(x)LDUMPLLISTLN(x)LPRINTOUTPIPOW(x,y)RENSIN(x), SIND(x)SQR(x)TG(x), TGD(x)