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--------------------------------------- GRAPHIC <mode> The GRAPHIC statement sets the current graphic mode. <Mode> is a numeric expression which normally ranges from 0 to 5, selecting one of the six graphic modes provided by EVS Basic. In addition to setting the graphic mode, executing this keyword also PAGEs the screen, disables all sprites, and, if setting a bitmap mode, sets the current pen to Pen 1. Adding 16 to the <mode> number causes the PAGE action to be suppressed, leaving both screen and cursor in an unknown state. Adding 128 to the <mode> number turns off the video display, which blanks the screen but also speeds up text mode program execution by about 7% (bitmap modes are not affected). The six basic graphic modes are described below: Mode Screen Color Charset 0 Text Normal ROM 1 Text Normal RAM 2 Text Multi RAM 3 Text Extended RAM 4 Bitmap Multi RAM 5 Bitmap Normal RAM A "Text" mode screen is a character-oriented screen of 1000 cells organized as 40 columns by 25 rows. Each cell may contain any of 256 characters. A "Bitmap" mode screen is a "dot"-oriented screen of 64,000 pixels organized as 320 columns by 200 rows. Each pixel may be either on or off. In any mode, the color of what is displayed on the screen depends heavily upon 1000 color cells. These are very similar to the character cells of the text screens and organized the same way. "Normal" color modes require the paper color to be the same in all 1000 cells, but allow one different ink color in each cell. "Multi" modes increase the number of different colors in a single cell from two to four at the cost of resolution (each dot in a multicolor character or bitmap pattern is twice as wide and there are only half as many). "Multi" text permits one ink color and three paper colors in a cell, while "multi" bitmap allows three ink colors and one paper color. "Extended" text color is very much like "Normal" text color, except that in exchange for reducing the number of different characters allowed from 256 to 64 this mode permits one ink and any one of four paper colors in a cell. Graphic mode 0 uses the normal V2 Basic "ROM" character set that cannot be altered by the programmer. The other modes share a "RAM" character set can be altered (redefined) by use of the IMAGE statement. Mode 0: this normal text mode is the same as the normal V2 Basic screen display. It is the default EVS Basic mode. Any execution error resets this mode so that the error message can always be read. Mode 1: this normal text mode is the first mode in which sprites and redefined character images can be made visible. Otherwise there is no apparent difference between mode 0 and mode 1. Mode 2: in multicolor text mode both normal and multicolor characters can be displayed. What kind of character appears in a given screen cell is determined by what its ink color is. Colors 0 to 7 give a normal character, while colors 8 to 15 give multicolor characters. Mode 3: in extended background color text mode the ink color of a cell is determined as with modes 0 and 1, but which paper color a cell has is determined by whether a character is printed as unshifted, shifted, reversed, or shifted-reversed. No matter how it is printed it will appear as the same unshifted character, but on different paper colors. Mode 4: this is multicolor bitmap mode. Each cell can support three ink colors in addition to the paper color. Resolution is lower in this mode than in mode 5, so lines can appear more jagged and characters may appear blockier. Mode 5: this is normal bitmap mode, in which each cell can support only the paper color and one ink color, but with twice the resolution of mode 4. This mode can display smoother lines and more detailed characters. Examples: 10 GRAPHIC 5 20 GRAPHIC A+16 --------------------------------------- IF <condition> THEN/GOTO <statements> [:ELSE <statements>] The V2 Basic statement IF has been modified to accept an optional ELSE statement on the same program line. Statements following ELSE are executed only if <condition> is false. There is no other change to the behavior of the IF statement. Examples: 10 IF A>0 GOTO 90 20 IF A$=B$ THEN PRINT "YES": ELSE PRINT "NO" --------------------------------------- IMAGE <exp>, <def$> The IMAGE statement is used to define sprite and character images. Which action is performed depends on whether <exp> is numeric or string. <Def$> must contain the binary pattern of the image being defined. If <exp> is numeric, IMAGE interprets it as a sprite image block number. Sprite image block numbers may range from 0 to 206 (these are the same image blocks that are assigned to sprites by SPRPIC. A sprite "looks like" the image in the image block currently assigned to it). Only 18 of the image blocks are guaranteed to be unused by EVS Basic for any other purpose, however. All other image blocks will replace parts of either a RAM character set or the bitmap screen. It is the programmer's responsibility to ensure that any such replacements have no effect on the program (for example, a program that only uses text modes will not be affected by having the bitmap overwritten with sprite images). Potential conflicts are outlined below: Blocks Conflict 0-15 None 16-47 Uppercase Charset 48-79 Lowercase Charset 80-204 Bitmap 205-206 None If <exp> is a string, the RAM charset pattern of the first character in the string will be replaced by the pattern in <def$>. IMAGE replaces the RAM character image only in the currently active character set, either the uppercase/graphics set or the lowercase/uppercase set. An exception here is that if the first character of the <exp> string is [RVS ON] (CHR$(18)), the reversed image of the second character in <exp> will be replaced. If the first character of <exp> is any other non-printable control character or <exp> is the null string, an "?UNKNOWN CHAR" error will result. IMAGE redefines as much of an image as possible, either until the image is completely redefined or until there are no more characters in <def$> (in which case the rest of the image is left as it is). A complete character image is 8 characters long, a complete sprite image 63. The same sprite or character image may be redefined as often as desired. Images may be defined in any graphic mode but they cannot be seen in graphic mode 0. Examples: 10 IMAGE "A", B$ 20 IMAGE A$, BIN$(B$) 30 FOR I= 1 TO 5: IMAGE I, A$(I): NEXT --------------------------------------- INFIX$([<start>,] <source$>, <replace$> [,<length>]) The INFIX$() function returns a string in which characters from <replace$> have overwritten characters in <source$> beginning at <start> and continuing for <length> characters. <Start> may range from 1 to 255. If <start> is not specified it is assumed to be 1 and replacement begins with the first character of <source$>. If <start> is larger than the length of <source$>, <source$> is returned. <Source$> and <replace$> may be any legal string expressions. If <source$> is the null string, the null string is returned. If <replace$> is the null string, <source$> is returned. <Length> may range from 0 to 255. If <length> is zero <source$> is returned. If <length> is not specified it is assumed to be 255. Replacement continues until <length> is reached or the end of <source$> or <replace$> is reached, whichever comes first. Examples: 10 A$= INFIX$("ABBBBB","B") 20 PRINT INFIX$(A$, B$, 5) 30 A$(I)= INFIX$(10, A$(I), "NULL RECORD") --------------------------------------- INK [<ink1> [,<ink2> [,<ink3>]]] INK sets the colors to be used by the three "pens". However, since in the text modes pen 1 is always considered the active pen, only the changes made to its color will be visible in those modes. Ink colors may range from 0 to 15. There is no prohibition against two or more pens sharing the same color. The default colors of pens 1, 2 and 3 are 14, 1 and 15, respectively. Ink (foreground) colors differ from paper (background) colors in that the ink color(s) can be different in each of the screen's 1000 color cells (a color cell colors either one character (text modes) or 64 pixels in an 8x8 block (bitmap modes)). Examples: 10 INK 14, 1, 15 20 INK , , A+2 30 INK , A(I) --------------------------------------- INPUT$( <length> [,# <lf#>]) INPUT$() returns a string of <length> characters from the keyboard or a logical file. INPUT$() accepts many characters which cause INPUT and INPUT# to terminate (eg., commas, quote marks, semicolons, colons, and [RETURN]). INPUT$() terminates execution only when the number of characters input reaches the desired <length>. <Length> can be any value from 0 to 255. A <length> of zero returns the null string. If <lf#> is not specified INPUT$() accepts input from the keyboard (no cursor is displayed). If a <lf#> is specified INPUT$() attempts to input from the associated device. For tape and disk files, if the end-of-file (EOF) marker is reached before <length> characters are input, INPUT$() will return a string of however many characters have already been obtained. This condition can be detected by checking the length of the returned string and/or the status variable ST. INPUT$() is not recommended for use with RS232 files. Examples: 10 A$= INPUT$(1) 20 A$= INPUT$(B, #4) 30 A$= INPUT$(1, #2): B$= INPUT$(8, #2): IMAGE A$, B$ --------------------------------------- INSTR([<start>,] <source$>, <pattern$> [,<matchtype>]) The INSTR() function searches <source$> for occurrences of characters in <pattern$> and returns either the position in <source$> at which the match condition became true (successful) or zero if the match condition never became true (unsuccessful). <Start> may range from 1 to 255. If <start> is not specified it is assumed to be 1 and matching attempt begins with the first character of <source$>. If <start> is larger than the length of <source$>, zero is returned. <Source$> and <pattern$> may be any legal string expressions. If either or both are the null string, zero is returned. <Matchtype> may range from 0 to 3. If <matchtype> is zero or not specified <source$> is searched for an exact match to <pattern$> ("AND" search). If <matchtype> is 1 <source$> is searched for the first character that does not match any character in <pattern$> ("NOT" search). If <matchtype> is 2 <source$> is searched for the first character that matches any character in <pattern$> ("OR" search). If <matchtype> is 3, INSTR() again searches for an exact match, except that any "?" character in <pattern$> matches any character in the same position in <source$> ("WILDCARD" search). Examples: 10 PRINT INSTR("ABCDEF","C") 20 IF INSTR(A$, "1234567890", 1 )> 0 THEN PRINT "NOT NUMBER" 30 ON INSTR("RWQ", A$) GOSUB 100, 200, 300 40 A= INSTR(B, A$, "B?B", 3)