Path: utzoo!utgpu!watmath!clyde!att!rutgers!tut.cis.ohio-state.edu!cwjcc!hal!nic.MR.NET!shamash!nis!ems!amdahl!uunet!mcmi!hdr!unocss!tucker
From: tucker@unocss.UUCP (Gregory A. Tucker)
Newsgroups: comp.sys.apple
Subject: Re: kermit and the lower left corner!
Message-ID: <541@unocss.UUCP>
Date: 5 Dec 88 00:55:20 GMT
References: <8811282050.aa14476@SMOKE.BRL.MIL>
Organization: U. of Nebraska at Omaha
Lines: 72

From article <8811282050.aa14476@SMOKE.BRL.MIL>, by STEVENS@SENECA.BITNET:
> i just received a copy of Kermit. and after four days i got it working!
> sort of anyway!
>  I have an Apple //e an extended 80 col. card, a ccs 7710 com card. the only thi
> ng cloned is my drive controller.
>  Everything works well until the data hits the lower left hand corner and begins
>  to scroll! then the first 3 or 4 characters get fuddled!
> EExmple! (if this is the bottom line)
> 
> i also have Ascii Express Professional and it does the same thing! all other fun
> ctions seem to work fine! In local mode I don't have this problem!
> 
> i have changed the 80 col. card, the com card, and all the Ram! the only thing e
> lse is the controller card and the mother board! self test says the Kernal is OK
> !
> so there we have it! I only have one question. ... WHY!!??
> If any one can help i sure would appreciate it!
> 
> Thanks Murray Stevens
> Stevens@Seneca
> (any spelling mistakes are a result of a poor upbringing) *thanks Mom*

I don't think there is one Apple user that hasn't had to fuddle with
this problem at one time or another in their Apple hacking career.
Let me explain the problem and the solutions.  

The whole problem is simply this: the Apple isn't fast enough to scroll
the 80 column screen before the next few bytes of information are
received by the modem.  The normal way of getting around this problem
is to turn on interrupts, which will automatically stop the screen
scrolling process and have the software put the x number of bytes
in a temporary holding place until the screen scroll can finish.  However,
you can still have problem even if your interrupts are set when
software, such as Kermit, uses the ROMs to do the 80 column scrolling
and your ROMs are not the enhanced ones.  The original ROMs were so
bug ridden that the scroll routines masked out interrupts during almost
the entire scroll process, resulting in the dropped characters you
now have. 

Here are my suggestions on repairing the problems:

1- Check to make sure interrupts are set.  However, this won't do any
   good with Kermit, assuming you have the unenhanced ROMs.  I don't
   what AE Pro did to deal with the problem.  Perhaps your manual
   would say.

2- With Kermit, put two commands in your Kermit.init file
   
       set flow xon
       set flow delay 100
  
   This will take care of the problem, but it will also make things
   slow going.  This sequence simply tells the host to stop sending
   data until Kermit can scroll the screen.  You may need to adjust
   the 100 after delay up or down.  (100 works on my system.)

3- Get a copy of ATP, this only 100% compatible VT-100 emulator. 
   (That I am aware of.)  It is share ware, but it is good quality
   nonetheless.  The programmer dealt with the interrupt problem
   by completely rewriting the scroll routines such that they work
   with no problems up to 9600 baud.  (I have not tested this.)

4- Enhnace your ROMs, if they are unenhanced.  This will cost you
   $70, though, and the ROMs aren't that much better that it is
   necessarily worth the price.  Fixing bugs is something I expect
   a company to do for free.

-- 
 ------------------------------+-------------------------------------------
 Gregory A. Tucker- Sophmore   | Internet: tucker%zeus.dnet@fergvax.unl.edu 
 Electrical Engineering        | Bitnet:   TUCKER@UNOMA1
 Univ. of Nebraska at Lincoln  | UUCP:     uunet!btni!unocss!tucker