Tech Arsenal 1/Tech Arsenal (Arsenal Computer).ISO/tek-07/settings.txt

Text File | 1991-08-27 | 8KB | 154 lines

TECHNICAL BULLETIN                                  LANAI/SETTINGS
LANtastic AI                                              08.05.91
LANtastic AI and setting IRQ, IOBASE and RAMBASE      Page 1  of 3

This bulletin should replace all other notes generated from this
office to date.

The following information is based on in-house testing and customer
support of LANtastic AI.  If you are not a registered LANtastic
owner, your questions should be directed to our technical sales
staff at [phone].  Any questions or comments on this
bulletin may be forwarded by FAX [phone] or mailed to :
Artisoft Inc., 575 East River Road, Tucson, AZ., 85704, ATTN:
LANtastic AI Support.

 RUNNING LANTASTIC AI AND SELECTING UNIQUE IRQ, IOBASE AND RAMBASE
SETTINGS

         There are three things that have to be uniquely selected
for the adapter to use, to let it co-exist with the other
components in the computer: the IRQ (Interrupt ReQuest line), the
IOBASE (beginning I/O port address), and the RAMBASE (the starting
address of high memory usage). If any other component is using the
same setting for any one of these parameters, this is what is
called a conflict. It is imperative that you avoid conflicts with
any of these three parameters. The signs of a conflict are:

         a) The device driver (i.e. WD8003 or NEX000) will lockup
            the computer.

         b) The device driver will return an error message telling
            you that there is a conflict with a certain parameter.

         c) Even if neither of the above occur, there may still be
            an error at the time of logging in: "Cannot Locate
            Network Name", which would be returned after ESCaping
            out of the "Waiting for server to come on-line"
            message.

         d) There would be some sort of problem in using the
            network for larger amounts of traffic: Executing
            a program from the server, or COPYing large amounts of
            files. It could give an error or just lock up the
            computer with a bleeping noise. (It's a dual tone
            'bleep', with the low tone first, and the high tone
            second, almost as if it were asking a question.)

         The IRQ is how the network adapter can get in touch with
the computer's CPU. It is akin to tapping the CPU on it's shoulder.
Thus the name: Interrupt ReQuest line. The CPU then pays attention
to the interruption. It will 'branch' to a section of code that has
the instructions for what to do when it is interrupted on a certain
IRQ line.

         If there is any other use of the same IRQ by a different
component in the computer, the instructions will not be
appropriate, the CPU will get confused, and will simply be unable
to do anything. Thus the 'lockup'.

         The IOBASE is the beginning address of which I/O port to
use. It can be thought of as a tunnel between the network adapter
and the CPU through which information flows. The only way for
external events (things happening on the bus) to be brought into
the computer is through I/O ports.

         So, if there is any other use of that tunnel by a
different component, the CPU would get confused, and would most
likely 'lockup' the computer. An IOBASE conflict can also show
itself at the time of running the device driver. It could return an
error saying that the adapter cannot be found.

         The RAMBASE is a bit more involved. DOS can formulate
addresses for RAM from 0-1 Megabyte (1Mb). There is a special range
of addresses that do not have any physical RAM associated with
them. This range of addresses extends from 640K to 1Mb. These are
hexadecimal numbers, and will thus have letters in  the CPU has to
know how to get to the information; it has to know how to address
the information. Thus, a contiguous section of these unused
addresses in the high memory area can be mapped to the onboard RAM
so that the CPU can get access to the information. This is the
RAMBASE setting.

         While IRQ and IOBASE conflicts most often result in a
'lockup', a RAMBASE conflict could also show itself as a disconnect
during increased use of the adapter; as the memory locations are
filled up by larger and heavier amounts of network traffic. If the
conflict were with the video adapter, you could see some sort of
screen corruption: 'garbage' characters, or funny colors, or a lock
up when the screen changes.

         There are several different components in the computer
that use high memory. The largest user of high memory is the video
adapter (VGA, EGA, and Hercules). The actual addresses used vary
greatly from video standard to video standard, manufacturer to
manufacturer, and from one mode of programming of the video adapter
to another: i.e. text vs graphics mode. It is important to identify
the range used by your video adapter by consulting the
documentation that came with it, talking to your vendor, or calling
the manufacturer. The hard disk controller also uses high memory to
map to it's onboard ROM chip, wherein the instructions for it's use
are kept. If any of you have done a low level format of a hard
drive, and have used DEBUG to issue the command "g=c800:5", you are
telling DEBUG to go to the address location C800, offset 5, and
execute the code contained there.

         The computer itself uses the F000-FFFF range for it's
system BIOS. That is, the addresses F000-FFFF are mapped to the
mother board's ROM chip. Quite often, 386 machines have a 'shadow
ram' option in the CMOS setup in the E000-EFFF range. This is where
information from the video adapter's relatively slow ROM chip is
read into the faster motherboard RAM (RAM that is beyond 1Mb), and
then has the E000 range of addresses mapped to it. This provides
faster video response.

         There can be software-based usage of high memory, too.
Programs like QEMM or 386-to-the-MAX will use high memory for
Expanded Memory Specification (EMS) memory or to load network
software or other programs into that high memory addressing range.
IBM/MS-DOS 5.0 also allows the use of high memory (Upper Memory
Blocks, according to Microsoft) to load DOS or other programs high.
If any of these products are involved, you will want to deactivate
them, temporarily, just to see what is actually going on. It is
always prudent to strip the machine in hardware (taking out
non-essential adapters), and software (REName the CONFIG.SYS and
AUTOEXEC.BAT files and reboot), to see if any of the things you
have taken out were involved in the problem. If the problem goes
away after doing these things, then you would want to build up the
complexity of the system, one step at a time, until you find out
what step re-introduces the problem.

         There are two approaches to finding available IRQ, IOBASE
and RAMBASE setting for the network adapter to use. Either:

         a) identify all the components in the computer, and the
            IRQ, IOBASE and RAMBASE that they use, to assign
            something else to the network adapter.

                                   OR

         b) systematically cycle through the available IRQ, IOBASE
            and RAMBASE options, until you stumble upon an
            available combination. It is important to have the
            systematic approach, so that you do not create a second
            conflict, alleviate the first one, and still be saddled
            with the second one.

          The selection of IRQ, IOBASE and RAMBASE invariably is a
two step process:

            1) Tell the adapter what combination you want.

            2) Tell the software (device driver) what combination
               you want to use.