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From: gaia@portia.Stanford.EDU (fai to leung)
Newsgroups: comp.sys.ibm.pc,comp.lang.pascal
Subject: Re: Various Turbo pascal questions
Keywords: Turbo pascal
Message-ID: <6972@portia.Stanford.EDU>
Date: 23 Nov 89 21:51:13 GMT
References: <2185@leah.Albany.Edu>
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In article <2185@leah.Albany.Edu> ppd491@leah.Albany.Edu (Peter P. Donohue) writes:
>
>   I have a few questions pertaining to programming in Turbo Pascal 5.5
>under the MS-Dos operating system. Any help with these would be
>appreciated. 
>
>  1) In an external data file (containing all ascii data), what is the
>maximum length of a line allowed? 

I would say 255 characters long.
Pascal strings format are byte[0]=length of string follow by the ascii chars.
 
>  2) Is there a way to read any text that has been written to a screen?
>I am writing a program that uses windows (that I write with pascal, not
>the program) and I would like to be able to reset what was on the screen
>after I clear a window.

Character=mem[ScreenBase:(Y*NumberofColumnsOnScreen+X) shl 1];

X,Y starts from 0!!! i.e. wherex-1,wherey-1

ScreenBase of Monochrome $B000;
Others $B8000;
for some VGA & EGA textmodes $A000 (43,50 lines modes)

>  3) Is there a way to read the 'variables' (I'm not sure of the exact
>name for them) that are set in AUTOEXEC.BAT with the SET command? An
>example is with the program, Procomm, they let you set the path to the
>program with the command 'SET PROCOMM=path'. Can you read what procomm
>is set to with TP5.5 and how would you do it. 

YourData=getenv(YourSetStringInEnvironment{e.g. 'PROCOMM});