Steven Lawrance's Operating System (SLOS), also known briefly as Steven Lawrance's Operating Program (SL-OP), was a small interpreted toy operating environment written in QBASIC for DOS. The primary motivation for writing this was to have an environment that supported long file names. This was written in 1993 -- two years before Microsoft released native long file name support in a consumer operating system with Windows 95.
SLOS was primarily distributed on the ContrailsBBS in Euless, Texas. It is now distributed from this web site.
Download CatSetup's required DLL files, if needed. Older versions of CatSetup required bwcc.dll, and the latest version requires ctl3dv2.dll. These go into the windows\system folder, not windows\system32. Windows computers typically already have ctl3dv2.dll installed, which is a Microsoft library, and Wine has a built-in implementation
Commands
Screen shot of what SLOS looks like on its first use, which runs a small installer to finalize the setupScreen shot of the DIR directory listing command
SLOS's command prompt permits the user to run any of the following commands from its smile emoticon :-) prompt:
SLTOOLS
Steven Lawrance's Tools
HELP
Help System
DIR
File Listing
CLS
Clears Screen
RUN program
Runs a Program
LOAD program
Loads a Program
EDIT
Creates a New DOS File
EDIT filename
Edits an SL-File
NEW filename
Creates a New SL File
FAT
Updates FAT
EXIT
Exits SL-OS
QUIT
Exits SL-OS
DEL filename
Deletes an SL-File
UNDEL
Undeletes an SL-File with a DOS name
UNDEL filename
Undeletes an SL-File with a DOS name
PURGE
Purges a Deleted SL-File
Scripting Language
SLOS executes script files having a "exc" file extension in an interpreted manner. Because this interpreter is running within the BASIC interpreter, execution speed is noticeably slow. The scripting language is difficult to read due to its overuse of abbreviations. CatSetup, by contrast, has a scripting language that is easier to write and read.
Syntax
The following commands are possible in a SLOS program. Each command appears by itself on its own line with no surrounding whitespace.
P!text
Prints text on the screen.
Example:
P!Hello!
How are you today?
I$nquestion
Asks a question. n=number of answers, question=text to display
Example:
I$2Do you? [Y] [N]
Ask "Do you? [Y] [N]" with 2 (Y,N) options
Y
User pressed Y
S#7
What to do when the user pressed Y
N
User pressed N
P!Why not?!
What to do when the user pressed N
ND
End application
P!Good!
Display "Good!" on the screen
ND
End application
I#nquestion
Just like I$nquestion, except it operates with numbers (not letters such as Y and N).
L#xxyy
Locates a position (xx,yy) on the screen.
Example:
L#3002
Locates (30,2) or (30,02) on the screen
S#line
Skips to a line in the program.
Example:
S#2
Skips to line number 2
P!Hi!
Prints "Hi!" at line number 2
D$command (II function)
Runs DOS program. Use II to set parameters. II isn't required.
Example:
P!Enter Parameters
II
Asks user to supply parameters
D$EDIT
Executes command "EDIT" Note: D$ can work by itself assuming II has a value
F$file
Loads a value into the file variable.
Example:
F$Configuration File
Sets "Configuration File" as the file var.
L!
Loads the string and number variable from file. Don't worry about it until you understand it.
SV$string
Sets the string variable.
SV#number
Sets the number variable.
Example:
SV$Hello there!
Sets string variable to "Hello there!"
SV#9
Sets number variable to 9
F$Hello!
Sets file variable to "Hello!"
S!
Saves string and number variables to "Hello!"
$givenvalue
If string variable equals givenvalue, execute next instruction. Else, execute instruction after next.
Example:
P!Enter a string value:
Types text on screen
V$
Asks user for the string variable
$Hello
If string variable = "Hello",
S#7
Go to line number 7.
P!You didn't type in "Hello"!
Else, print text.
ND
Exit
P!You typed in "Hello"!
Print text
ND
Exit
#givennumber
If number variable equals givennumber, execute next instruction. Else, execute instruction after next. Note: This is just like $givenvalue, except a number should be in the givennumber.
Example
The following example is a very trivial animation program named "Animation Master" in SLOS. It requires the user to hold down a key to switch between two screens to make the user think that the person is talking.
C!
P!Animation Master v2.1
P!Version for SL-OS
P!
I$4Ready for some fun? [Y] [N]
Y
S#15
y
S#15
N
S#13
n
P!You don't know what you are missing!
ND
C!
P! . .
P! . - , I talking!
P! ---
L#0120
I$2Press [1] for next frame, hold [1] for animation, or [0] to exit.
1
S#25
0
ND
C!
P! . .
P! . - Hello, am !
P! \___/
L#0120
I$2Press [1] for next frame, hold [1] for animation, or [0] to exit.
1
S#15
0
ND
Limitations
SLOS's scripting environment contains a large list of limitations, and some are expressed in the following list:
