旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 � � � � � AT&T PC6300 SUPPORT BBS - Bulletin Service � � � � SUBJECT: GW-BASIC Notes for the PC6300 � � PROVIDED BY: AT&T PC-Hotline � � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 � � � DIFFERENCES BETWEEN IBM BASIC VERSION 1.1 AND GW-BASIC � � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 � � � 1) IBM COMPATABILITY PACKAGE MODIFICATIONS � � � � 1.1) RESERVED WORDS AND TOKENS � � The reserved words and tokens were incompatable, � � making exchange of binary and protected program � � files impossible. GW-Basic token values have been � � modified by this modification package. � � � � 1.2) LINE PRINTER AND KEYBOARD OPEN MODE � � IBM Basic allows these devices to be open without � � a mode specification. GW-Basic would interpret � � these cases as open for random and declare a mode � � error. � � � � 1.3) RS232 SUPPORT � � The /C switch on the IBM Basic command line allows � � the user to specify the sieze of communications � � buffers. This feature has been added to all � � versions of Basic. � � � � 1.4) CLEAR Processing � � CLEAR should turn off music, reset music to � � foreground, turn off PEN and STRIG, and reset DRAW � � scale color. Similar processing should happen for � � LOAD, RUN, CHAIN, CLEAR, and NEW. This processing � � has been added for all GW-Basic versions. � � � � 1.5) BSAVE and BLOAD � � IBM Basic appends the .BAS suffix to file names � � when the user does not supply a suffix. GW-Basic � � did not append a suffix. � � � � 1.6) CENTER OF GRAPHICS SCREEN � � IBM Basic calculates the center by dividing the � � one relative screen dimensions by two. GW-Basic � � calculates the center by dividing the zero � � relative screen dimensions by two. The IBM Basic � � method of calculating the center of the screen is � � now used by GW-Basic. � � � � 1.7) COMMON STATEMENT � � IBM Basic allows the user to define new variables � � using the COMMON statement. GW-Basic declared an � � error if a COMMON statement referred to a � � previously undefined variable. � � � � 1.8) LIST STATEMENT � � During PRINT and LIST processing, IBM Basic clears � � characters from the end of the print item to the � � end of line. All versions of BASIC now function in � � this manner. � � � � 1.9) CURSOR DESIGN � � A) The GW-Basic cursor is on only during character � � input requests from the keyboard. � � B) The IBM Basic displays different cursors for � � the Screen Editor overstrike mode and insert � � mode. � � The GW-Basic cursor is now turned off when � � printing characters to the screen. The cursor is � � turned to the user cursor when the PRINT � � statement terminates. When input is requested, � � the cursor is turned to the insert mode cursor � � or the overwrite mode cursor, depending on the � � Screen Editor mode. � � � � 1.10) INKEY$, INPUT$, INPUT � � A) INKEY$ did not return the same key codes as � � IBM Basic � � B) INPUT$ did not return the same key codes as � � IBM Basic. It should be noted that IBM Basic � � key codes returned to INKEY$ are not the same � � as IBM Basic keycodes returned to INPUT$ for � � all keys. � � C) Device input from "KYBD:" read no break (no � � interrupt takes place) if using the INPUT � � statement. An interrupt took place if � � INPUT$(N,kybd:) IS SPECIFIED. � � GW-Basic now provides the OEM with filters for � � mapping characters on input. These filters � � provide the capability of returning IBM Basic � � keycodes. � � � � 1.11) CHR$ � � Certain IBM character codes in the range � � [&H00,&H1f] have been assigned fonts and are � � printable. Other codes in this range have been � � assigned functions (such as carriage return). � � GW-Basic now provides filters which allow OEM to � � decide which codes in this range are printable � � and which specify control functions. � � � � 1.12) SCREEN function � � SCREEN function requests for the character at the � � current cursor position may return a zero in � � place of &H20 (space) for IBM if there are no � � non-space characters to the right of the � � specified cursor position. GW-Basic can now � � support this character code for the screen � � function. � � � � 1.13) POKE/PEEK � � Results of the POKE and PEEK statements were � � different. The GW-Basic machine interface now � � includes routines to filter PEEK and POKE � � instructions. The OEM may now modify the PEEK or � � POKE address and data value. Certain GW-Basic � � routines have been provided for use in these � � filters. GW-Basic provides the capability to � � support the function of all PEEK and POKE � � locations specified by IBM user documentation. � � � � 1.14) INITIALIZATION DIFFERENCES � � A) HEADING: GW-Basic displays the heading when a � � program is specified on the command line, � � while IBM Basic does not print a heading or � � display function keys in this case. The � � GW-Basic machine interface now contains a � � parameter that specifies to GW-Basic whether to � � print the heading and function keys when a � � program is specified on the command line. � � B) FUNCTION KEY DISPLAY: GW-Basic did not give the � � option of displaying the function keys when � � BASIC initializes, when there is no program on � � the command line. A configuration switch now � � specifies the function key display switch � � position on BASIC initialization. � � � � 1.15) ERROR CODES � � Some of the error codes and messages were � � different. GW-Basic error codes and messages have � � been modified to conform to IBM Basic. � � � � � � 1.16) MUSIC AND SOUND � � A) PLAY octave default not the same. � � B) BEEP duration not the same � � C) SOUND STATEMENT: � � 1)SOUND freq,0 causes the IBM Basic to be � � flushed � � 2)GW-Basic does not perform range checking on � � frequency. � � 3)SOUND statement foreground mode was not � � interruptable by CTL-C or BREAK. This is a � � problem because it is possible to create � � extremely long notes. � � These conditions are considered bugs and have � � been fixed for all versions. Foreground SOUND � � interruptability is available through a GW-Basic � � keyboard routine provided to the OEM for use � � within the speaker control support. � � � � 1.17) COLOR statement syntax � � The IBM COLOR statement syntax was not � � supportable by the GW-Basic OEM interface. This � � problem has been fixed in GW-Basic. � � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 � � � 2) DIFFERENCES WHICH WILL NOT BE RESOLVED � � � � 2.1) SCREEN EDITOR DIFFERENCES � � (THESE DIFFERENCES MAY NOT EXIST IN SOME VERSIONS � � OF GW-BASIC BECAUSE OF THE FLEXIBILITY OF THE OEM � � INTERFACE FOR MAPPING AND OMITTING FEATURES) � � � � A) Input sequences that wrap to a subsequent � � physical line cause a scroll to open another � � physical line. IBM Basic allows the user to � � type over the text which is on the subsequent � � line. The IBM Basic end of logical line is then � � moved to the end of the logical line which is � � being overwritten. � � B) Skip-to-next-word function. When the cursor is � � positioned on a space the IBM skip-to-next-word � � control function will skip spaces until a word � � is found, progress over the word and proceed to � � the word following. The GW-Basic skip-to-next- � � word control function will skip spaces until a � � word is found. � � C) TAB. In GW-Basic, after stopping at the last � � position on a line, TAB will proceed to the � � next line. IBM Basic TAB only operates on one � � line. � � D) Cursor movement control functions do not join � � physical lines into logical lines. In IBM Basic � � cursor movement can join lines. � � E) Line delete. The GW-Basic Screen Editor uses a � � character other than ESC for line delete. � � F) GW-Basic extends logical lines to new physical � � lines (when required by LF or wrapping at the � � end of the screen). A new blank line is inserted � � following the current line. When physical lines � � following the first physical line in a logical � � line are deleted, the line is removed from the � � screen. In IBM Basic, lines are not inserted or � � removed. � � G) AUTO. The IBM AUTO statement allows the user to � � modify the statement corresponding to the line � � number printed by AUTO only. If the user uses � � the Screen Editor to move to another line, or � � otherwise attempts to modify the line number, � � strange results are obtained. The GW-Basic AUTO � � statement allows the user to modify any line by � � making use of the Screen Editor to modify the � � line number or to move to another line on the � � screen. � � H) Functions added to Screen Editor � � 1) HELP. This control function allows the � � programmer to edit the last statement where � � an error ocurred, or if no error ocurred, � � the last direct statement. � � 2) DELETE WORD. This control function deletes � � the current word starting at the current � � cursor position, and ending at the character � � previous to the next word � � 3) CLEAR TO END OF SCREEN. This control � � function clears all data from the current � � cursor position to the end of the screen. � � � � 2.2) Breaking from INPUT � � IBM Basic allows the user to break from an INPUT � � statement using either Control-C or BREAK. GW-Basic � � provides only one BREAK function code. This � � function code may be assigned to either BREAK, � � Control-C, or both by the OEM. However, no special � � processing is performed to differentiate between � � the INPUT statement and other statements. � � � � 2.3) Sequences returned by the GW-Basic RANDOM NUMBER � � GENERATOR (RND function) will NOT be identical to � � sequences returned by the IBM Basic random number � � generator. � � � � 2.4) /F and /S Options � � IBM Basic statically allocates file space using � � the /F and /S BASIC command line switches. GW-Basic � � allocates space dynamically and is not limited by � � these switches. GW-Basic will not declare an error � � if the user specifies either of these switches. � � � � 2.5) File Format of BASIC � � IBM Basic is in ".COM" file format. GW-Basic is in � � ".EXE" file format. � � � � 2.6) Fielded Strings � � IBM Basic fielded strings retain their values � � after the file is closed. In GW-Basic this space is � � deallocated. Any field statement which is executed � � while a file is opened, has no effect after that � � file is closed. For example, assume file 1 is � � opened, fielded, and closed. If file 1 is � � reopened, it should be refielded. � � � � 2.7) VARPTR � � In IBM Basic, the value returned by VARPTR for a � � given file number is not subject to change during � � program execution. In GW-Basic, FBD's are moved in � � memory when files are opened and closed. To avoid � � problems due to this difference, the statement � � "X=VARPTR(file)" should be executed before every � � referrence to X because a file buffer may be moved � � in memory when another file is closed. � � � � 2.8) Line Printer Filenames � � Line printer filenames have the following syntax: � � "LPTn:[bin]" � � Where if bin is included, the file is opened in � � Binary mode. In this mode, tabs are not expanded � � to spaces, and CR is not forced at end-of-line. � � � � 2.9) DATE$ � � Both IBM Basic and GW-Basic allow a single digit � � for year. IBM Basic interprets the digit 8 as � � 1980. GW-Basic interprets the digit 8 as 2008. � � � � 2.10) Pen and Joy Stick � � The statement 'STRIG ON' and 'STRIG OFF' perform � � no function in GW-Basic. In IBM Basic these � � functions are used to enable and disable the joy � � stick trigger interrupts. � � � � 2.11) Parity Checking on the OPEN statement � � There is an undocumented PE on the IBM OPEN � � statement. This OPEN option enables/disables � � parity checking on input. With no PE specified, � � the IBM OPEN for communications will report no � � parity errors. � � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 � � � 3) IBM BASIC PROBLEMS FIXED IN GW-BASIC � � � � 3.1) Homing The Graphics and Text Cursor � � IBM Basic does not home the cursor after CLS in � � version A1.0. GW-Basic allows the OEM to choose � � when to home the graphics cursor. The text cursor � � is always returned home as per IBM PC Basic � � version A1.1. � � � � 3.2) NAME statement On Open Files � � IBM Basic allows the NAME statement to refer to an � � open file. This causes no immediate problem, but � � can lead to problems as in the following case: � � 10 OPEN"0",#1,"JUNK" � � 20 NAME"JUNK" AS "JUNK2" � � 30 KILL"JUNK2" � � 40 PRINT#1,"My data" � � 50 CLOSE � � IBM Basic allows this program to execute. Data � � printed to the file is lost. This is inconsistent � � in that KILL is illegal when referring to an open � � file. � � GW-Basic and the standard MS-DOS version of � � BASIC-86 do not allow NAME to refer to open files. � � � � 3.3) Detection Of Identical File Names � � IBM Basic does not detect identical file names � � when the only difference in the name is the case � � of the alphabetic characters comprising the file � � name. This problem prevents IBM Basic from � � detecting that a file in an OPEN statement has � � already been opened. � � GW-Basic and the standard MS-DOS version of � � BASIC-86 are able to detect this user error. � � � � 3.4) Interruptability Of Input From The Keyboard � � Variable length input (INPUT n,var...) from � � the keyboard is not interruptable using the break � � key. The program: � � 10 OPEN "KYBD:" FOR INPUT AS 1 � � 20 INPUT #1,A$ � � 30 GOTO 20 � � will read break as a character (the program is � � virtually uninterruptable). This problem is fixed � � in GW-Basic. � � � � 3.5) Communications � � 1) End Of File. IBM-PC Basic returns EOF true � � whenever the input buffer is empty. GW-Basic � � returns EOF true only when file was opened in � � non binary mode, and CTL-Z has been received. � � Once EOF is true, it remains true until the � � file is closed. This is more analogous to the � � way EOF works on other devices. � � 2) Default Data Bits. IBM Basic documentation � � states that the default bit count for � � communications is 7. The commas in the � � statement: � � OPEN "COM1:,,," � � cause 7 bit mode to be invoked. However, if � � parity or speed are specified, the default data � � bit count is set to 8. GW-Basic defaults to 7 � � data bits. � � � � 3.6) Graphics � � 1) POINT. The IBM BASIC POINT function does not � � detect that certain coordinates are not on the � � screen and therefore are not legal. � � 2) GET and PUT. The array format and speed � � capability of these statements is supportable � � by GW-Basic. However, the operation of these � � commands is highly dependent on hardware design � � and the implementation of OEM specific � � routines. � � � � 3.7) Screen Editor � � 1) The IBM Screen Editor returns a zero to input$ � � function when a null function key is depressed. � � GW-Basic Screen Editor returns no key code to � � INPUT$ for null function keys. � � 2) The IBM Screen Editor terminates function key � � expansion when a key code greater than &H7f is � � encountered. The high bit of this key code is � � removed. GW-Basic allows codes greater than � � &H7f. In late ROMs, the IBM Screen Editor will � � not remove the high order bit from codes � � returned by function key expansion. � � � � 3.8) Trailing Blanks � � The following BASIC program demonstrates a problem � � in IBM Basic: � � 10 OPEN "JUNK FOR OUTPUT AS #1 � � 20 PRINT #1,"ABC " � � 30 CLOSE #1 � � 40 OPEN "JUNK" FOR INPUT AS #1 � � 50 INPUT A$ � � 60 PRINT LEN(A$) � � 70 CLOSE #1 � � The IBM Basic result of the print statement in � � line 60 is 13. The trailing blanks have not been � � removed. GW-Basic removes these trailing blanks as � � specified by the ANSI Standard. � � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴캑 � � � 4) RS232 COMMUNICATIONS � � � � Previous releases of GW-Basic were incompatable with � � IBM-PC Basic communications in the following areas: � � 1) When a com file was opened with default � � parameters and closed, a CONTROL-Z (1A hex) was � � sent to let the other end of the RS-232 � � protocol know that end-of-file had been � � reached. This is not done in IBM-PC BASIC. � � 2) Under GW-Basic if a COM device was opened with � � the BIN option, EOF always returned false. In � � ASCII mode, EOF returned false until it � � received a CONTROL-Z, after which time it � � always returned true. � � These changes made EOF behave in a device independent � � manner. For example, a program which was written to � � read sequentially through a disk file, stopping when � � EOF was true, can now be used to read a COM file. For � � another example, GW-Basic can load "COM1:" and terminate � � when the load is finished if the user on the other end � � of the RS232 line types SAVE "COM1:",A. � � � � The number of application programs which have been � � written to use IBM-PC COM cannot be ignored. The � � following change in GW-Basic is intended to provide � � compatability with IBM-PC Basic while retaining the � � features added to GW-Basic. � � NOTE: This change is isolated to version independent � � code and has no effect on OEM written routines. � � � � COM files can be opened in one of the following ways: � � � � 1) With the ASC option � � In this mode, EOF is always false until a CTL-Z � � is received. When a file is opened for OUTPUT � � or RANDOM, a CTL-Z is sent when the file is � � closed. � � � � 2) With the BIN option � � In this "raw" mode, Basic performs no filtering � � of data. This includes forcing carriage return � � when line width is exceeded. This option � � overrides the LF option. EOF has the same � � meaning as it does in IBM-PC Basic. EOF is TRUE � � if no data exists in the input buffer. � � � � 3) With neither the BIN nor the ASC options. � � This mode is compatible with IBM-PC Basic. No � � CTL-Z is sent when the file is closed. EOF is � � TRUE if no data exists in the input buffer. � � � � BSAVE, BLOAD force the mode to BINARY. This insures � � BASIC will not force any Carriage Returns if the device � � is not 255 (infinite). � � � � SAVE "COMn:...",A forces the mode to ASCII. � � � � LOAD 'COMn:..." forces the mode to ASCII if the first � � character received is less than 80 hex, indicating an � � ASCII file is being loaded. This ensures that ASCII � � LOADs will terminate. � � � � COM file syntax: � � "COMn: [speed] [,parity] [,data] [,stop] [,RS] � � [,CS[n]] [DS[n]] [,CD[n]] [,LF] [,ASC] [,BIN]" � � Where: � � SPEED baud rate in bits per second � � PARITY N, E, 0 (none, even, odd) � � DATA 5,6,7,8 bits per byte � � STOP 1, 1.5, 2 stop bits � � Default for baud greater than 110 is 1 � � Default for 110 baud or lower & 5 data bits � � is 1.5 � � Default for 110 baud or lower & 6-8 data bits � � is 2 � � RS Suppress RTS (Request To Send) � � CS[n] Controls CTS (Clear To Send) � � DS[n] Controls DSR (Data Set Ready) � � CD[n] Controls CD (Carrier Detect) � � This is also referred to as RLSD � � (Receive line Signal Detect) � � LF Send a Line Feed character (X'OA') � � following a Carriage Return (X'OD') � � ASC Open COM file in ASCII mode � � BIN Open COM file in BINARY mode � � � � The RTS (Request To Send) line is turned on when you � � execute an OPEN "COM..." statement unless you include � � the RS option. � � If CD is omitted, it defaults to CSO � � If DS is omitted, it defaults to DS1000 � � If CS is omitted, it defaults to CS1000 � � If RS is specified and CS is omitted, then CS defaults � � to 0. � � � � Normally I/O statements to a communication file will � � fail if the CTS (Clear To Send) or DSR (Data Set Ready) � � lines are not cabled. The CS and DS options allow you � � to avoid this problem by ignoring these lines. If the � � [n] argument is included, it specifies the number of � � milliseconds to wait for the signal before returning a � � "Device Timeout" error. � � � � If the argument [n] in the CS, DS, and CD options is � � omitted, or equal to 0, then that line's status is not � � checked at all. � � � � NOTE: The speed, parity, data, and stop parameters are � � positional, but RS, CS< DS, and CD may appear in any � � order after STOP. � � � � When included in the parameter list, LF will cause a � � Line Feed to be sent after a Carriage Return. � � � � � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸