Possibilities - Realities 10/90

Contact:   eSoft, Inc. (Makers of TBBS)
           15200 E. Girard Ave., Suite 3000
           Aurora, CO  80014
           (303) 699-6565      Voice
           (303) 699-6872      Fax
           (303) 699-8222      BBS
           support@esoft.com   E-Mail

REALITIES 10/90
---------------

*** From October 1990 Possibilities Newsletter ***
*** Copyright 1990 by eSoft, Inc.  All Rights Reserved ***

REALITIES...how to make it work
by eSoft Technical Support Staff

From the moment you first install TBBS, it's easy to see the possibilities are 
almost endless.  Turning those possibilities into realities can bring up 
questions.  For this reason, quality customer support is at least half the 
overall value of any software package. 

We recommend you call the eSoft Support BBS (303-699-8222) and read through 
the messages in each of the various support areas.  You could find answers to 
your questions, even before you've asked them!  You'll definitely get some 
useful tips and ideas for bringing possibilities to life with tbbs.  In this 
section of the newsletter, we will answer some of the more commonly asked 
questions we receive. 

A Way NOT to Expand...

Q. I recently received a new software catalog, and came across a program that 
claims to make my 80286 AT extended memory or even some free disk space act 
like EMS (expanded) memory.  The catalog says the program will use up to 32 
Meg of my hard disk and as much extended memory as I have as expanded memory.  
It also claims that it's LIM 3.2 and LIM 4.0 compatible, and totally 
transparent.  Will it work with TBBS? 

A. TBBS places very high demands on expanded memory.  Expanded memory (also 
known as EMS or LIM memory) is "page switched" memory, meaning that small 
chunks of memory are transferred in and out of a special "window" in low 
memory (where DOS can get at it).  The speed of EMS memory is directly 
proportional to the speed at which the EMS software is capable of switching 
memory in and out of the memory window.  

TBBS requires a page switching speed of no slower than 200 microseconds (200 
ms), with speeds of 100  ms or better being preferable.  EMS simulation 
schemes, like the program you mention, do not have page switching speeds 
nearly fast enough to accommodate TBBS.  Such schemes are functional in single 
user environments, for such uses as spread sheets etc., but offer far too low 
a performance level for a high speed, multi-user environment like TBBS.  
You'll need to obtain an actual EMS hardware/software solution. 

You may use the program EMSTEST (supplied with TBBS) to test proper 
installation of EMS memory and also the page switching speed.  If EMSTEST 
shows page switching speeds which are many times slower than the 200 
microsecond range TBBS will probably malfunction attempting to operate in that 
type of memory. 

NOTE:  If you have a 386 based PC, you may also use QEMM or 386MAX, which 
offer true EMS memory.  (See Possibilities Vol. 1., No. 4, August, 1990 for 
more information on EMS memory.) 

On-Screen Fireworks Display...

Q. I just saw what looked like a fireworks display on my TBBS local console!  
I brought up the system, and suddenly the screen was covered with funny 
colored characters.  I rebooted, brought it up again, and was able to sign on, 
but then the system locked up.  What the heck is going on? 

A. You've allowed your system to experience a serious condition - operating 
with no messages in the system.  TBBS version 2.1 must have at least ONE 
message in the system at all times, even if your system doesn't ordinarily 
deal with messaging. 

To repair the situation, locate disk 1 of your TBBS master disks.  In the 
MESSAGE sub-directory, you'll find two files, named MSG.BBS and MSGHDR.BBS.  
Copy the two files to your hard disk TBBS directory.  The system should return 
to normal. 

To keep this problem from happening again make sure that at least one message 
is always maintained on the system.  

If you don't use message areas on your system, once you've copied the new 
files from the TBBS diskette, just ensure that MFSQZ (the TBBS message base 
maintenance utility) is never run to squeeze old messages from the system.  If 
you ran the TBBS installation program, MFSQZ is configured to delete messages 
older than 90 days twice each week.  Use CEDIT to delete the external event 
from the system that causes MFSQZ to be invoked. 

Dirty Cache...

Q. I've heard that adding a disk cache to my system will dramatically 
improve performance.  Which one should I use with TBBS? 

A. Computer performance can be improved with a disk cache, but to what extent 
is dependent on the situation.  Generally, we do not recommend the use of 
software based disk caching in conjunction with TBBS, as it adds a memory 
resident program to your system which can sometimes cause conflicts or 
anomalous behavior that is difficult to diagnose.  These problems often show 
themselves in ways that don't appear to be remotely related to the disk cache.  

Software disk caches use a small portion of the CPU's power to perform their 
job.  In some cases, the trade-off between using part of the CPU power and the 
performance of the cache can nullify  the potential gains. 

It is usually necessary to "tune" a disk cache program to the task you are 
performing.  If you have assigned either too much or too little memory to the 
cache, it can even slow down disk access when compared to having no cache at 
all. 

Some hard disk controllers have built-in disk caching.  These schemes off- 
load the entire job of disk caching to hardware, thereby not loading the CPU 
at all.  In addition, it almost totally eliminates the possibility of 
conflicts with system software.  This is more expensive, but is a much more 
desirable approach. 

If you feel you must use a software based disk cache, stick with highly rated 
cache programs such as Super PC-Kwik from Multi-Soft, or PC-CACHE (included 
with PC Tools Deluxe) from Central Point Software.  In addition, you MUST 
disable write caching entirely, or file damage will almost certainly occur in 
a multi-user environment like that of TBBS. 

If you install a disk cache and begin to see problems with your TBBS system, 
your first troubleshooting step should be to disable the cache software.  If 
the problem goes away, then check your cache installation carefully. 

Regretting the Technology Shift...

Q. With much excitement, I recently purchased a USRobotics Courier HST Dual 
Standard modem.  After downloading a Tech Note from your Support Board that 
told me how to set the modem up and following its directions to the letter, I 
thought I was home free.  The modem appears to work, but when people upload 
files to my TBBS, they get a lot of errors.  Ymodem-G uploads consistently 
abort!  What's wrong with the modem?  Have I done something wrong? 

A. Nothing is wrong with the modem, and it sounds as though you've done 
everything right.  

The problem centers around your hard disk sub-system.  When incoming data is 
written to disk, the controller locks-out the CPU during its DMA data 
transfer.  Each character that comes in from the modem causes the serial port 
to create a CPU interrupt. When the CPU is locked out, the serial port's 
attempt to interrupt is delayed for so long that a second character overwrites 
the one waiting before the CPU can respond.  Because of the resulting data 
loss, file uploads contain significant errors or are aborted altogether. 

The problem can be eliminated by replacing the serial controller chip -- 
called a UART -- with a special buffered UART.  The buffered UART is a 
National Semiconductor NS16550A.  It is pin-compatible with most common UARTs 
found in PCs, and is also pin-compatible with the UARTs found in all DigiBoard 
cards sold by eSoft.  

Additional information about this, including how to install the UARTs, can be 
found in a Tech Note on the eSoft Support Board.  Select <T>ech Notes from the 
Main Menu, then file area 1, then view or download TECH10.TXT.  (See the 
Status section on page 12 for information on how to reach the eSoft support 
BBS.) 

- END -
PS1090-2
Rev. 10/90

Copyright (C) 1994 eSoft, Inc., All Rights Reserved.  Permission granted
to distribute this file in its entirety, without modification, to any
interested party.  Any other use requires the written permission of
eSoft, Inc.

IMPORTANT:  The information herein is subject to change without notice.
Please call or write to confirm factual information of importance to you
or your organization.

