GOS is an Operating System - BASIC Extension hybrid written for Commodore 64 computers between 1992 and 1995.

GOS features a disk cache, readahead disk buffer, memory manager, memory compression, mouse support, BASIC variable transfer, linking BASIC files and external commands loaded from diskette.

Thanks to its disk cache and track buffer, the external commands are as fast as the internal commands.

Approximately 19 years later I've recovered my GOS diskettes, work diskettes and some of the documentation and transferred them to the modern medium. However, the organization of the material and remembering/reverse-engineering my own code takes time. I'll fill the missing information in time.

As an appetizer, here is a working diskette of GOS:

Download: http://cbm.ficicilar.name.tr/dosya/gos95.zip

Version: 1995.10.14-19:37
Date: October 1995
Programmer: Ilker Ficicilar

I haven't documented all of the commands and features online yet. So, here is the part 1:

GOS 95 Commands:

command: dir
parameters: -
type: internal
definition: Shows directory of the active disk.


command: cat
parameters: -
type: diskette
definition: Shows directory of the active disk.

command: status
parameters: -
type: diskette
definition: Shows the status of the cache, memory, fastID and fastopen.

command: mem
parameters: -
type: diskette
definition: General memory status of the BASIC.

command: drive
parameters: {drive no}
type: internal
definition: Sets the active disk drive number. 
            The drive no is in between 8 and 11.

command: path
parameters: {path}
type: internal
definition: Sets the directory path for external commands.

command: drvset
parameters: {on|off},{on|off}
type: internal
definition: Sets on or off the fastID and fastopen functions respectively.

command: dump
parameters: -
type: diskette
definition: Shows the values of the active BASIC variables.

command: scrollup
parameters: -
type: diskette
definition: Scroll the screen one row up.

command: volume
parameters: {0-15}
type: diskette
definition: Sets the SID volume. It's value is in between 0 and 15.

command: type:
parameters: {file name},{drive no}
type: diskette
definition: Displays the contents of a text file.

command: baspack
parameters: -
type: diskette
definition: Packs the loaded BASIC program to reduce its size in the memory.

command: italic
parameters: -
type: diskette
definition: Converts the screen font into italic font.

command: movie
parameters: {file name, without mv0. prefix},{drive no}
type: diskette
definition: mv0. type animation files are played with this command.

command: cls
parameters: [{screen no}]
type: internal
definition: Clears the screen. 
            Clears the default screen 0 or the screen no given.

command: screen
parameters: {screen no}
type: internal
definition: Displays the given screen number. 
            Screen no 8 is the graphics screen, 0-2 are the text screens.

command: pass
parameters: {screen no}
type: internal
definition: Sets the active screen for output.
Example: pass1:cls:print"hello world":screen1
         This technique prepares the screen first, then displays it.

command: swap
parameters: -
type: diskette
definition: Swaps screen 0 and 1 in turn. 
            It changes both the screen and active output.

command: flip
parameters: -
type: diskette
definition: It only swaps active output in turn, without changing the display.

command: color
parameters: {border and screen color},{font color},{gfx screen colors}
type: internal
definition: Sets the colors.
            Graphics screen colors = background*16+foreground color.

command: picput
parameters: {file name},{drive no}
type: diskette
definition: Saves the graphics screen.

command: show
parameters: {file name},{drive no}
type: diskette
definition: Loads and displays the graphics screen.

command: hear
parameters: -
type: diskette
definition: Outputs the digital audio sampled by an ADC digitizer
            connected to the 2nd Joystick port.
            Press CTRL-J or fire button of the joystick to stop.

command: dsp
parameters: {number of times},{speed}
type: diskette
definition: Shows the sound waves of the digital audio sampled
            by an ADC digitizer connected to the 2nd Joystick port.

command: makehi
parameters: -
type: diskette
definition: Converts the normal text screen into Hires graphics screen.

command: makehi
parameters: -
type: diskette
definition: Converts the normal text screen into Hires graphics screen.

command: makelow
parameters: -
type: diskette
definition: Converts the graphics screen into text screen 
            by redefining the character map.

command: key
parameters: [{definition},{0-15}]
type: diskette
definition: Defines the function keys and shows the current definitions.
            Defines 16 key combinations in total.

command: del
parameters: {line numbers}
type: diskette
definition: Deletes the given line numbers in a BASIC program.
Example: del130-180

command: renum
parameters: {first line number},{increase}
type: diskette
definition: Renumbers the line numbers of a BASIC program.

command: erase
parameters: -
type: internal
definition: Clears the cache memory.

command: reset
parameters: -
type: internal
definition: Resets to initial configuration; without erasing memory.

command: cset
parameters: {0|1}
type: internal
definition: Sets the character set.
            0=Capital letters, 1=Lower case letters.

command: block
parameters: {C|M|T}{X1},{Y1},{X2},{Y2},{X3},{Y3}
type: diskette
definition: Copies (C), moves (M) or transfers (T) a block 
            defined by X1,Y1,X2,Y2 in the text screen to X3,Y3.

command: fill
parameters: {S}{X1},{Y1},{X2},{Y2},{Char}
type: diskette
definition: Fills the area defined by X1,Y1,X2,Y2
            in the text screen with {Char} character.

command: dot
parameters: {X1},{Y1},{0|1}
type: diskette
definition: Sets or clears a pixel in the graphics screen.

command: locate
parameters: {X1},{Y1}
type: internal
definition: Sets the cursor coordinate in the text screen.

***

GOS System Registers and Vectors

IV1: $19,$1A
IV2: $1B,$1C
IV3: $1D,$1E
IV4: $A3,$A4
IV5: $C3,$C4
IV6: $FB,$FC
IV7: $FD,$FE
PR1: $1F
PR2: $20
PR3: $21
PR4: $02
PR5: $97
PR6: $D7
PR7: $FF
DR: $14,$15
DR1: $14
DR2: $15
FAC: $61-$65
ARG: $69-$6D
SGF: $66
SGA: $6E
SGC: $6F
OVF: $68
RD: $70


IV: Indirect Vector
PR: Pseudo Register
DR: Decimal Register
FAC: Floating Point Accumulator
ARG: Floating Point Argument
SGF: FAC's sign
SGA: ARG's sign
SGC: The result of compared signs
OVF: Overflow bit of FAC
F: FAC's Registers
A: ARG's Registers

***

Short Memory Map

$0401-     : BASIC area.
$CC00-$CFE7: Text screen.
$E000-$FF3F: Graphics screen.
$C000-$CBFF: Transient command area.
$6000-$6FFF: ML Monitor.
$7000-$9FFF: GOS

***

The work diskette includes additional fonts and example simple animation files.

Also, other than the listed above, there are more commands in the work-diskette, including commands for training and using artificial neural networks.

They will be covered in Part-2, together with the memory map.

İlker Fıçıcılar
29.07.2014

Keywords: GOS, Commodore 64, Operating System