Simons' BASIC is an extension to BASIC 2.0 for the Commodore 64 home computer. Written by British programmer David Simons in 1983, who was 16 years old at the time, it was distributed by Commodore as a cartridge.
It is widely, but incorrectly, called "Simon's BASIC", because of confusion between the first name "Simon" and the surname "Simons".
Features
Simons' BASIC added an array of features to Commodore BASIC 2.0:Simons' Basic User Manual (published by Commodore) 114 additional keywords commands to ease the coding of sprites commands to ease the coding of high-resolution and multicolor graphics commands to ease the coding of sound commands to aid in structured programming keywords to assist in writing and editing BASIC programs, similar to those in the VIC-20 Programmer's Aid cartridge
Programs written in Simons' BASIC could employ hexadecimal numbers in assignments and calculations by including a prefix, or binary numbers by utilizing a prefix.
Because a portion of the cartridge data is mapped into memory at addresses , which overlaps part of the standard C64 BASIC RAM, the amount of available memory for BASIC programs was less than that of a standard C64 configuration.
An extension was written by Simons and released by Commodore on floppy disk and tape as Simons' Basic Extension. This software is also known as Simons' Basic 2. It could not be released on cartridge because the original Simons' Basic cartridge had to be present in order to use the extension. Simons' Basic Extension adds another 91 commands including the much-coveted command which renumbers the destinations of and statements.Simons' Basic 2 User Manual (published by Commodore)
The 114 keywords
Sprite (MOB) handling keywords MOB SET – enables a sprite and defines its attributes MMOB – positions a sprite on the screen RLOCMOB – causes a sprite to smoothly move from one location to another CMOB – sets up the two global colors for multicolor sprites MOB OFF – disables a sprite DETECT – initializes sprite collision detection CHECK – checks for a sprite collision
High resolution graphics handling keywords HIRES – initializes a high-resolution graphics mode MULTI – initializes a multicolor graphics mode NRM – returns to the text display LOW COL – changes the plotting colors HI COL – returns to the original plotting colors PLOT – draws a pixel LINE – draws a line CIRCLE – draws a circle ARC – draws an arc ANGL – draws the radius of a circle PAINT – performs a flood fill REC – draws a hollow rectangle BLOCK – draws a solid rectangle DRAW – draws a user-defined set of lines ROT – sets scaling factors for DRAW CHAR – plots a text character on a high-resolution screen TEXT – plots a text string on a high-resolution screen TEST – determines whether a pixel is plotted or empty
Other graphics handling keywords COLOUR – sets the background and border colors; the British spelling is used CSET – selects a character set MEM – copies character ROM to RAM BCKGNDS – configures extended background color mode FLASH – sets up a screen color to flash OFF – cancels a previous FLASH directive BFLASH – causes the screen border to flash FCHR – fills an area of the text screen with a given character code FCOL – changes character colors for a selected area of the screen FILL – a combination of FCHR and FCOL MOVE – copies a section of the screen INV – displays a screen area in reverse LEFT – scrolls the screen left RIGHT – scrolls the screen right UP – scrolls the screen up DOWN – scrolls the screen down GRAPHICS – reserved variable that always equals (the VIC-II chip's base address) SCRSV – saves a text screen to tape or disk SCRLD – loads a text screen from tape or disk
Sound handling keywords MUSIC – plays a series of notes based on the contents of a string variable PLAY – determines whether the program continues to run during MUSIC VOL – specifies the master sound volume WAVE – specifies a voice type ENVELOPE – sets ADSR parameters for a SID voice SOUND – reserved variable that always equals (the SID chip's base address)
Keyboard input handling keywords FETCH – takes user input with restrictions defined by the command INKEY – checks for a function key press ON KEY – checks for a given keypress, then performs a branch if present DISABLE – disables the previous ON KEY directive RESUME – reenables the previous ON KEY directive
Input peripheral handling keywords JOY – reads a joystick POT – reads a paddle PENX – reads the light pen's horizontal position PENY – reads the light pen's vertical position
Sprite/custom character definition keywords @ – describes one line in a sprite or custom character graphic DESIGN – uses neighbouring @ lines to define a sprite or custom character
Error trapping keywords ON ERROR – sets up a routine to trap error conditions OUT – ends an error handling routine NO ERROR – cancels ON ERROR and restores normal BASIC error handling
Disk handling keywords DIR – displays the disk directory without destroying the BASIC program in memory (Drive #8 only) DISK – sends a string to the disk drive's command channel (Drive #8 only)
Printer handling keywords HRDCPY – sends the text screen to the printer COPY – sends the high-resolution screen to the printer
String manipulation keywords INSERT – inserts one string into the middle of another (Note: There is no dollar sign after INSERT, unlike other string operators such as STR$, LEFT$, RIGHT$, etc.) INST – similar to INSERT, but overwrites rather than inserting. (Note: As with INSERT, there is no dollar sign after INST.) PLACE – searches for one string in the middle of another DUP – duplicates a character string a given number of times. (Note: As with INSERT, there is no dollar sign after DUP.)
Text formatting keywords PRINT AT – prints a string at a given screen location CENTRE – centers a character string on the screen; the British spelling is used USE – formats numeric data in strings based on a template, just like PRINT USING on other advanced versions of BASIC on other computers, e.g. the Commodore 128, for example. LIN – returns the vertical position of the cursor
Maths keywords Note: These operations are restricted to values that fit into a 16-bit unsigned integer, instead of the full floating-point range used by the built-in BASIC arithmetic operations and functions. MOD – performs a division operation and returns the remainder DIV – performs a division operation and returns the integer quotient FRAC – isolates the fractional portion of a number EXOR – performs an exclusive-OR logical operation
Programmer's aid keywords AUTO – automatically generates line numbers as a BASIC program is entered RENUMBER – renumbers a BASIC program (but does not fix GOTO/GOSUB statements) OLD – undeletes a program accidentally removed by the NEW command KEY – assigns a string as a macro to a function key DISPLAY – displays all function key macros MERGE – merges a BASIC program from tape or disk into the program currently in memory PAGE – displays a BASIC program listing in page format OPTION – highlights Simons' BASIC keywords when using the LIST command DELAY – varies the rate at which the LIST command scrolls the screen FIND – searches the program for a string TRACE – displays the line numbers as a program is running RETRACE – displays results of a trace DUMP – displays all variable values except for arrays COLD – resets the C64
Security-related keywords DISAPA – marks a BASIC program line for hiding SECURE – hides all lines marked with DISAPA so that they cannot be viewed with LIST
Structured programming keywords ELSE – allows an alternative branch for IF/THEN conditionals REPEAT – start of a REPEAT/UNTIL loop structure UNTIL – defines the loop condition for a REPEAT/UNTIL loop structure, and marks its end RCOMP – reinstates the most recently used IF/THEN/ELSE conditional LOOP – defines the start of a loop that will run until an EXIT IF conditional is true EXIT IF – the conditional is true, so it exits the current LOOP/END LOOP structure END LOOP – defines the end of a loop that will run until an EXIT IF conditional is true PROC – defines the start of a named subroutine END PROC – defines the end of a named subroutine CALL – jump to a named subroutine defined with PROC/END PROC, and stay there EXEC – call a named subroutine defined with PROC/END PROC, then return LOCAL – redefines variables for use in structures GLOBAL – reverses the effects of a previous LOCAL command
Miscellaneous keywords CGOTO – equivalent to GOTO, but accepts calculated expressions RESET – moves the DATA pointer to a given line number PAUSE – pauses program execution for a specified number of seconds
Other $ and % are also considered keywords, for a total of 114.
Trivia The band Barcelona titled their 1999 debut album Simon Basic in tribute. The album includes the song "C-64".
Reception Creative Computing stated that Simons' BASIC "almost makes the 64 into a new computer. (Probably the one it should have been in the first place.)" It praised the "very fine manual" as a contrast to Commodore's usually poor documentation, and predicted that it would become "the standard language for programming the machine … Commodore had better be planning to manufacture lots of copies because they will go fast". Ahoy! wrote "If you do any programming in BASIC and should happen to see this product on a dealer's shelf, do not ask any questions—do not hesitate—just buy it!" The magazine praised Simons' BASIC's power and "excellent manual", and stated that "its price makes it one of the biggest bargains available for the Commodore 64". RUNs review was less favorable, stating that its "many powerful and useful commands … were, unfortunately, implemented very poorly for a commercial package. There is very little command parameter checking, and many things have been overlooked or ignored."
The original SIMONS' BASIC cartridge (without the extension) has no provisions for reading the error channel on the Commodore 1541 and Commodore 1571 disk drives, nor can it perform a DIRectory listing of files or issue a DISK command on any disk drive other than Drive #8 when more than one disk drive is connected to the Commodore 64. And while most "standard" BASIC 2.0 keywords can be abbreviated by typing the first or first and second letters and then holding down the SHIFT key while typing the second (or third) letter after that, all SIMONS' BASIC keywords must be completely spelled out in full exactly as shown in the accompanying user's manual. This includes the commands COLOUR (which selects the background color and exterior border color), and CENTRE (which prints text message that are "centered" on the screen), both of which are spelled as in British English and are incorporated that way into SIMONS' BASIC.
References
External links Simons' Basic User Guide on Internet Archive by David Simons, Commodore Computers, 1983. Downloadable as PDF. Simons' Basic Italian Reference Guide by David Simons, Commodore Editor, 1983. Lemon64 Forum topic with some informal information from David Simons himself.