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PeasyDos Basics guide for Version 1.0 (C) 1988 Duncan P Charlton and Sue E Horseman This document provides a guide to the operation of the PeasyDos environment and instructions on how to use the programming language in order to build a shell for your system. 1 PEASYDOS OPERATION 1.1 Input to PeasyDos Whenever PeasyDos is not carrying out one of your commands it will be waiting for you to tell it what to do next. There are two methods that allow you to give PeasyDos instructions: Menus, where you choose one option from a list of many; and the Line Editor where you have to type in a line of text. 1.1.1 Menus PeasyDos menus appear on the top two lines of the screen and consist of a list of options, one of which is highlighted (the current option) and below that a more detailed description of the current option. There are two ways of selecting an option from the menu. (a) Use the <LEFT> and <RIGHT> cursor keys to move to the desired option and then press <RETURN> to select the option. As you move through the options the text below will change to give an explanation of the current option. (b) Press the key corresponding to the first letter of the option. If there is only one option beginning with that particular letter then that option will be selected. If more than one option begins with that particular letter then a new menu will appear with just those options shown. At this point you can use the cursor keys as described in (a), or continue typing the option name until the desired option is selected. At times a Menu will be too long to be accommodated by the width of the screen. This will be shown by small arrows at the right or left hand side of line 1 indicating that the menu continues off the screen. If this happens the <Ctrl> <LEFT> or <Ctrl> <RIGHT> keys can be used to view options off the screen. If you simply use the <LEFT> or <RIGHT> cursor key the Menu will 'scroll' to accommodate the new options. Although the menu might be too long to be shown this will not affect the methods of selecting options described in (a) and (b) above. 1.1.2 Line editor At times you will be asked to type in a line of text, for example when specifying the drive for a format operation or a filename in a rename operation. At these times the text you type will appear on line 23 of the screen and you can type your text or use the keys below to edit what you are typing: <DEL> Delete character under cursor <DEL RIGHT> Delete character before cursor <HOME> Move to start of line <END> Move to end of line <Cursor LEFT> Move cursor back one character <Cursor RIGHT> Move cursor forward one character <Ctrl> <HOME> Delete all of line <RETURN> When you have finished typing the line Sometimes a default option will appear before you have typed anything, if you want to accept the default then just press <RETURN>. If not, you can edit the default with the keys listed above. If you want to get rid of the default altogether, use <Ctrl> <HOME> to delete the whole line. 1.2 Areas of the screen PeasyDos uses five main areas of the screen to provide you with information 1.2.1 The menu bar occupies the top two lines of the screen and is used to show the menus described in section 1.1.1 above. 1.2.2 The Editor uses line 23 of the screen as described in section 1.1.2 above. 1.2.3 Line 24 of the screen is the status line and contains a copyright notice and the PeasyDos version number. 1.2.4 The Message line occupies line 25 of the screen and PeasyDos will display helpful instructions there. 1.2.5 The rest of the screen is used by individual PeasyDos application to display relevant information. 1.3 Running a PeasyDos Program. To execute a Peasydos program type dosman <filename> where <filename> is the name of the PeasyDos program file that you have created. 2 PROGRAMMING IN PEASYDOS. In order to configure PeasyDos to your own system you must create a program file. You can do this using any text editor, for example the Sidekick editor (or even Edlin!). If you are familiar with another procedural programming language such as BASIC, Pascal,C or the DOS batch file language you should find the example given below fairly easy to understand and you may find the PeasyDos Language Description that follows it to be sufficient to allow you write your own PeasyDos programs. Before we present an example program there are a few things to note about a PeasyDos program. Programs consist of a list of Commands that tell PeasyDos what to do next, PeasyDos will simply run through the list executing the commands. As well as commands there are Functions. These cause PeasyDos to evaluate the function and return a value. Finally there are Variables. These are used to store values and are given a value with the SET Command. The maximum length of a variable name is 8 characters. Example of a PeasyDos program PeasyDos was originally written to provide a menu driven interface for selecting programs and so the first function that you will need to use will probably be the MENU function. Let's look at an example, SET MENUVAR MENU "Format" : "Format a Disk", "Diskcopy" : "Copy a Floppy Disk", "Exit" : "Exit to DOS" ENDMENU This means SET the variable MENUVAR to be equal to the result of the function MENU. The text following the keyword MENU indicates the possible options for that menu. The left column indicates the choices in the menu and the right column the explanation that will appear when the corresponding option is highlighted. When the above example is encountered in a program file a menu would be displayed looking something like this FORMAT Diskcopy Exit Format a Disk where the capital letters indicate that the word 'Format' will be highlighted on screen. When one of the options is selected, (see Menus above) the variable MENUVAR will take on one of the values "Format", "Diskcopy" or "Exit". So far so good, now we need to take different actions according to the value of MENUVAR. The easiest way to do this in PeasyDos in to write a list of commands for each option and have PeasyDos execute the section corresponding to the value of MENUVAR. Lets ignore the sections of code for the moment and just look at how we make the selection. GOSUB MENUVAR That was pretty painless wasn't it? The GOSUB (GO SUBroutine) instructs PeasyDos to execute the program lines at MENUVAR until it encounters a RETURN command, and then to continue with the commands after the GOSUB. At the moment MENUVAR is either "Format", "Diskcopy" or "Exit" so we need three pieces of program to deal with those three options. Let's write the one for 'Format' first.. :Format RUN "FORMAT A:" RETURN The colon in the first line indicates that 'Format' is a label, or name, for a piece of code. The command RUN will execute the expression after it, as if you had typed it at the DOS prompt. The second line, therefor, has exactly the same effect as typing FORMAT A: at the prompt, ie the DOS FORMAT command will be executed to format a disk. Lastly the RETURN statement tells PeasyDos to go back to where it was before it called this subroutine. Here are the other subroutines: :Diskcopy RUN "DISKCOPY A: B:" RETURN :Exit EXIT :Diskcopy is almost exactly the same as Format. :Exit is a bit different, it has a new command EXIT. All it does is exit from PeasyDos back to the DOS prompt. Now let's look at the complete program. :MAINLOOP SET MENUVAR MENU "Format" : "Format a Disk", "Diskcopy" : "Copy a Floppy Disk", "Exit" : "Exit to DOS" ENDMENU GOSUB MENUVAR GOTO "MAINLOOP" :Format RUN "FORMAT A:" RETURN :Diskcopy RUN "DISKCOPY A: B:" RETURN :Exit EXIT END Note that there are three more lines in the program :MAINLOOP GOTO "MAINLOOP" END :MAINLOOP is another label and GOTO "MAINLOOP" instructs PeasyDos to loop back to MAINLOOP. This means that the program will continually: display the main menu perform the operation and, redisplay the menu until Exit is selected. END simply tells PEASYDOS that it has reached the end of the program file. So that's a simple PeasyDos program. You can adapt and extend it to fit your own system. 3. PeasyDos Language Definition and Description for Version 1.0 3.1 Backus-Naur definition The following is the Backus-Naur Form (BNF) definition of the PeasyDos Programming Language: EXPRESSION EVALUATION <primitive> ::= <variable> | <constant> | <function> <rlnl-op> ::= $= | == | < | <= | >= | > | <> <rlnl-expr> ::= <expr> | <expr> <rlnl-op> <expr> <expr> ::= <primitive> { & <primitive> } COMMANDS <set-cursor-command> ::= @ <expr> <expr> <chdir-command> ::= CHDIR <expr> <clear-command> ::= CLEAR <display-command> ::= DISPLAY <expr> <exec-command> ::= EXEC <expr> <exit-command> ::= EXIT <gosub-command> ::= GOSUB <expr> <goto-command> ::= GOTO <expr> <if-command> ::= IF <rlnl-expr> <statement> <loud-command> ::= LOUD <message-command> ::= MESSAGE <expr> <return-command> ::= RETURN <run-command> ::= RUN <expr> <set-command> ::= SET <variable> <expr> <shell-command> ::= SHELL <expr> <silent-command> ::= SILENT FUNCTIONS <curdir-function> ::= CURDIR <dosver-function> ::= DOSVER <edit-function> ::= EDIT <expr> <expr> <files-function> ::= FILES <expr> <menu-function> ::= MENU <expr> : <expr> {, <expr> <expr> } ENDMENU <menulist-function> ::= MENULIST <expr> <nextkey-function> ::= NEXTKEY <sortlist-function> ::= SORTLIST <expr> <subdirs-function> ::= SUBDIRS 3.2 Language description. 3.2.1 Relational operators. The following relational operators are supported: $= String equality $<> String inequality == Numeric equality < Numeric less than <= Numeric less than or equal >= Numeric greater than or equal > Numeric greater then <> Numeric not equal Relation operators return either the string "True" or "False" Note that PeasyDos is a typeless language, no distinction is made between strings and numbers or lists, different operators are provided for example, string comparison and numeric comparisons. This means firstly that care must be taken to use the correct operator eg. "0123" $= "123" is False, but "0123" == "123" is True. If a non-numeric string is used in a numeric comparison it will be given the value zero for example "Hello" == "World" is true since both strings will have the value zero. 3.2.2 Term level operators Concatenation of strings is provided by the & operator eg. "Hello " & "World" is equivalent to "Hello World" at present no arithmetic operators are provided. 3.2.3 PeasyDos commands. @ x y Sets the cursor to the position x,y. eg. @ "0" "0" homes the cursor CHDIR new-directory Sets the current directory to new-directory, if new-directory does not exist exits PeasyDos with an error. eg. CHDIR "\" Sets the current directory to the root directory CLEAR Clears the screen DISPLAY <expr> Displays <expr> at the current cursor position then performs a CR/LF. eg. @ "0" "10" DISPLAY "Hello world!" displays Hello World on the tenth line of the screen. EXIT Leaves PeasyDos GOSUB <expr> Executes the statements at the label <expr> until a RETURN is found. At this point control is returned to the next statement. eg. GOSUB "Format" jumps to the label Format and executes the statements until the next RETURN Note the quotes around 'Format', if they are omitted as in, GOSUB Format the Variable Format will be evaluated and PeasyDos will jump to that label, this is a very useful device - see the example program for how to use it. GOTO <expr> Transfers control directly to the label <expr>. IF <rlnl-expr> <statement> If <rlnl-expr> is True then executes <statement> otherwise continues execution on the next line. eg. IF MENUVAR $= "ESC" GOTO MAINLOOP LOUD Puts PeasyDos into Loud mode, see description of SILENT command. MESSAGE <expr> Displays <expr> on the message line eg. MESSAGE "Press the space bar to continue" RETURN See GOSUB command RUN <expr> Clears the screen displays <expr> and executes it eg. RUN "WS" runs the Wordstar wordprocessor SET <variable> <expr> Sets <variable> to <expr> eg. SET GREETING "Hello world" SHELL <expr> Same as RUN but displays "Press any key to Return to PeasyDos" and waits for a keypress before returning to PeasyDos. SILENT Puts PeasyDos into Silent mode. This is similar to ECHO OFF in DOS batch files in that commands are not displayed before being executed. LOUD puts PeasyDos back into Loud (the default) mode. 3.2.4 PEASYDOS FUNCTIONS. CURDIR Returns the current DOS directory DOSVER Returns the DOS version number EDIT <expr1> <expr2> Waits for and returns a line of input from the user, <expr1> (which can be the empty string "") is provided as a default and at most <expr2> characters can be entered. eg. SET NEWDISK EDIT "A:" "2" FILES <expr> Returns a list of all the files in the current directory that match the mask <expr>. eg. SET CFILES FILES "*.C" MENU <option> : <exp> {, <option> <exp> } ENDMENU Returns the selected value from the menu. <option>s are the choices to be displayed, <exp>s are the more detailed explanations of those choices. If the <ESC> key is pressed the function will return the value "ESC". MENULIST <expr> Same as MENU except that it takes a list, for example the list of files returned by FILES, and produces a menu from that. In this case only options are given and not explanations. eg. SET FILEVAR MENULIST FILES "*.*" will display a menu of all the files on the disk and return the selected files. NEXTKEY Returns the next key pressed. SORTLIST <expr> Sorts a list such as that returned by the FILES functions into alphabetical order. eg. SORTLIST FILES "*.*" SUBDIRS Returns a list of all the subdirectories of the current directory. Now available in Version 1.2 New operators + Numeric plus - Numeric minus / Numeric DIV % Numeric MOD * Numeric multiplication $< Alphabetically less than $> Alphabetical greater then New commands SETTATT <file> <att> Sets file attributes SETDISK <drv> Set default drive WHILE <rlnl-exp> 'While' flow of control construct .... WEND New functions BIGMENU <list> <ipl> Like MENU but uses the whole screen and allows more than one option to be selected. DSPACE <drv> Returns disk free space FDATE <file> Returns date stamp of <file> FSIZE <file> Returns size of <file> FTIME <file> Returns time stamp of <file> GETATT <file> Returns the attributes of <file>. HEAD <list> Returns the head of <list> MID <s> <n><expr> Returns <n> chars from <expr> starting at <s> TAIL <list> Returns the tail of <list> VOLLAB <drv> Returns Volume label of disk in specified drive LICENSE COPYRIGHT (C) 1988 Duncan P Charlton All Rights Reserved. This is the shareware version of PeasyDos, the programmable DOS shell, if you would like the full version, which incorporates many advanced features, and a printed manual and programmers guide, then please send £30.00 to: Duncan P Charlton The Old School House Southstoke Bath BA2 7DU You are free to use, copy and distribute PeasyDos for noncommercial use providing all the following conditions are observed. No fee is charged for use, copying or distribution. The program is not modified in any way. The file LICENSE.TXT is distributed with all copies.