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/// Usenet Review:  Commodore A2386SX Bridgeboard
    By Matt Guthrie


        Commodore A2386SX Bridgeboard


        (From the User's Guide:)  "The Amiga Bridgeboard is an expansion
board that gives your Amiga IBM PC/AT compatibility, while retaining all the
Amiga's advanced features."

        The bridgeboard comes with necessary floppy drive cables, a User's
Guide, a Commodore MS-DOS (ugh!) 5.0 Reference Manual, and the usual
warranty registration card and FCC Statement (at least here in the U.S.).
Mine also included a "Bridgeboard Addendum" stating that my bridgeboard was
shipped with an upgraded 386SX processor (a 25MHz model, rather than the
usual 16MHz or 20MHz).  The 5 included floppy disks were:  Amiga Janus, PC
Janus, and MS-DOS 5.0 (3 disks).


        Name:           Commodore Business Machines, Inc.
        Address:        1200 Wilson Drive
                        West Chester, PA  19380

        (Commodore has different addresses outside the U.S.)


        $999 (US) is the last list price I have seen, but no one is paying
more than $200-$250 here in the USA.  I paid $208.30 (US) to have it
delivered to my door (after an 11-week wait).



                The documentation states that the bridgeboard may be
                installed in any A2000 or A3000 series Amiga.  AGA machines
                are not mentioned.

                No minimum memory requirement is mentioned.  The bridgeboard
                uses its own RAM and comes with 1MB onboard (expandable to

                A hard drive is not required, although the documentation
                states that running from floppy disks is slower, and
                requires more frequent disk swapping (no kidding!).  (Note:
                the INSTALLATION section of this review assumes a hard drive
                installation.  If you don't have a hard drive, you're on
                your own.  Why didn't you buy a hard drive instead of a


                The bridgeboard works under both Release 1.3 and Release 2
                of the operating system.  (Again, AGA machines are not


        Amiga 3000, 25MHz
        2 MB Chip RAM, 4 MB Fast RAM.
        2 internal floppy drives:  1 normal, 1 dual-speed.
        2 internal hard drives:  52MB and 212MB.

        AmigaDOS version: 2.04
        Kickstart: version 37.175
        Workbench: version 37.67


        The hardware installation instructions are clear and have several
illustrations to help you.  There are separate installation sections for
A2000's, A3000's, and A3000T's.  It is important to follow the manual since
there are some jumpers on the bridgeboard that need to be set prior to
inserting it into your Amiga.

        The trickiest part of the installation is deciding what your floppy
setup is going to be.  You can use PC floppy drives in an internal bay, you
can declare Amiga floppy drives as "PC Only" or "Shared", and you can connect
external Amiga drives directly to the bridgeboard.  There are several
combinations, but in any event, no more than 2 floppy drives are accessible
by the bridgeboard.  I opted to declare my dual-speed floppy as shared, and
not connect the normal floppy.

        Depending on your choice of floppy drives, you set the jumpers,
connect the cables, and plug in the board.  It was a somewhat tight fit, but
I found that "see-saw"-ing the board (first one side, then the other) got it

        Installing the software comes next.  The Amiga Janus uses the
standard Installer utility, and I had no problems there.  You can create an
Autoboot virtual drive at this point or later; I chose later.  Two programs
from the Amiga Janus disk are worth mentioning.  PCPrefs is a utility to
define bridgeboard parameters.  You need to declare at least your floppy
drive setup and video mode (monochrome or color) before you can boot the
bridgeboard.  The manual explains the necessary options quite well.  Flipper
is a utility that automatically detects whether the disk you insert is a DOS
or AmigaDOS disk.

        The hardest part of the install for me was repartitioning my hard
drive.  I had been using a dedicated partition with IBeM (a software PC
emulator); since the bridgeboard uses a virtual drive (one big file on the
Amiga side), I had to back up my partition to DOS floppy, delete the
partition, and then make the new virtual partition and restore all my
software.  What a pain.  Those of you moving up from software emulators, set
aside some time for this.  Again, the instructions on making a virtual drive
are clear.  The manual states that you should add 30 to 50 buffers per
megabyte of virtual drive size to the partition with the virtual drive.
This visibly speeds up performance.  I made a 20MB partition and did not
create a JLINK drive, which is a non-booting virtual drive that grows as you
fill it (an Autoboot drive has a fixed size).

        You then boot the bridgeboard and run the BIOS Setup utility.  You
have now crossed over to the DOS domain (novice adventurers beware!).  You
again have to declare your floppy configuration and video mode.  If you have
additional RAM or a dedicated hard drive, you also declare those here.

        Now comes the first real problem I ran into.  The section of the
User's Guide that covers DOS installation tells you very little; it
frequently refers to the "DOS User's Guide" (I assume they mean the DOS
Reference Manual) and its instructions on using the DOS installation
utility.  Well, the DOS Reference Manual is a straight reprint of the
Microsoft one, and Microsoft publishes the installation instructions in a
separate booklet, "Getting Started with MS-DOS," which Commodore does not
include with the bridgeboard.  Fortunately, I have done this several times
before.  After you exit the BIOS setup, the bridgeboard reboots.  If you
hadn't inserted the first MS-DOS diskette yet, do so, then give the
bridgeboard the DOS variant of the 3-fingered salute to reboot:
Ctrl-Alt-Del.  DOS is then booted from floppy.  Now you must format your
virtual hard disk.  The manual states that FDISK and FORMAT are run by the
DOS installation utility automatically; I ran them myself.  They are both
straightforward to use, and explained in detail in the DOS Reference
Manual.  To install DOS, just type "install" at the DOS "A>" prompt.  It
walks you through.

        I also had problems installing the PC Janus software. It doesn't
completely install if you follow the instructions in the guide, which tell
you to enter "xcopy a:janus c:janus".  After typing that, you must also
type "xcopy a:dos c:janus" to get the rest of the Janus files to your hard
drive.  Appendix E shows that all of the DOS files are supposed to be in the
Janus subdirectory, but in fact, the following four files are in the dos
subdirectory:, keyboard.sys, emm.sys, and


        Since the bridgeboard is so versatile, I will not spend much time in
this REVIEW section.  I have not tried many things that others will;
hopefully some other people will post their experiences.  Some notes about
expansion, though:

        RAM -- the bridgeboard uses 80ns page mode ZIPs.  (The 16MHz model
can use 100ns ZIPs.)  It comes with 2 of the 4 banks filled with 256Kx4
chips; you can add 1MBx4 chips 1 bank at a time, or replace the 256Kx4 chips
with 1MBx4 chips.

        Hard disks -- you can add a dedicated PC hard disk, which supposedly
runs much faster than the virtual drives.  Using the ADISK utility, you
can even have an Amiga partition on the PC hard drive.

        FPU -- you can add an 80387 numeric coprocessor to the board.

        Video adapters -- the Amiga supports MDA (monochrome) and CGA modes
through the native display.  If you add a video adapter board, you must hook
up a monitor directly to the adapter card.  In my opinion, this would suck.
I have heard vague accounts of switchers that will allow you to use one
monitor with two RGB inputs.  If I get a VGA board, I will certainly invest
in one of these.  Another drawback is that you cannot see the PC screen on
the Workbench (or use Amiga-M to toggle screens) because you must disable
the MDA/CGA emulation if you install an adapter board.

        Printing -- the bridgeboard can use the Amiga's serial or parallel
ports for printing.  On the Amiga side, you run a program which gives
control of the PAR: or PRT: device to the bridgeboard.

        Modems -- you must install an internal modem card or a serial card
for the bridgeboard to use; it cannot use the Amiga's serial port for
modem access.

        I use the bridgeboard to run Quattro Pro and PAF (Personal Ancestral
File, a genealogy program).  For DOS programs such as these I find the
bridgeboard works quite well.  You may quite logically argue that a '386
is overkill for such applications.  In the future I plan to add a
multipurpose board like the Cardinal SoundVision and run Windows or Linux.
I also plan to try some (S)VGA games.  (When I do, I will post a followup

        Here are some performance numbers from Norton's SI utility, both for
the bridgeboard and my '386/33 at work (by the way, a rating of 1.0 is
equivalent to an 8088 XT):

                        Bridgeboard (in CGA mode)               PC

CPU speed:              18.9                                    36.0

Hard disk:               4.6                                     7.2
Avg seek:                0.0                                    14.86 ms
Track-track:             0.0                                     3.60 ms
Xfer rate:              348.8 KB/sec                            747.3 KB/sec

Overall:                14.1                                    26.3

        Note:  When running on the bridgeboard, Norton warned that an
"advanced disk controller" was found.  Apparently, such controllers are
often designed such that they only move the heads when data is actually
read/written (so the seek times are invalid -- as if you couldn't tell).  It
also warned that all numbers for the hard disk are probably better than
actual.  I suppose you really want a dedicated hard disk if you are doing
disk-intensive work.


        Included documentation is the A2386SX Bridgeboard User's Guide and
the Commodore MS-DOS 5.0 Reference Manual.  The MS-DOS Reference Manual is
straight from Microsoft, so it is as good (or bad) as anything that
Microsoft does.  The bridgeboard user's guide is professionally printed,
easy to read, and, aside from the errors noted in INSTALLATION, accurate.
The appendices contain handy technical information.


        The ability to run programs like Quattro Pro and have the system keep
up with my keystrokes is nice ;-).  My software-only emulator dragged

        I can finally access 1.44MB floppies!  IBeM with the MSH filesystem
couldn't handle these.  (Of course, I could have bought CrossDOS or AmigaDOS
2.1, but I hate buying commercial software unless I really have to, and I'm
waiting for AmigaDOS 3.1.)

        AREAD and AWRITE are cool.  They allow you to copy a file from an
MS-DOS filesystem (hard drive or floppy) to any Amiga volume.

        The Flipper program that detects whether you inserted a PC or Amiga
floppy in a shared drive is a little slow.  Having installed *numerous*
multidisk software packages on PC's, I like to hit the Return key as soon as
I have inserted the next disk.  You can't do that with my setup; you have to
wait about 2-3 seconds for Flipper to react.  Otherwise, the read is
corrupted, and you have to reinstall.  The solution, of course, would be to
have a PC only floppy drive.  Oh, well.  At least I can listen to a MOD
while installing DOS software.

        The method of partitioning a hard drive for MS-DOS use is more
intuitive to me than the bridgeboard's method of using one big file as the
DOS filesystem.  I would think it would be faster, too, but who knows?  It
would have been nice to avoid the hard disk reorganization, but that is a
relatively minor complaint.

        My ego would be greatly bolstered if my bridgeboard had faster Norton
numbers, but I suppose the decrease is due to communication between the
Amiga and the bridgeboard.  It is unrealistic to suppose that the
bridgeboard will be as fast as a straight PC with the same processor.

        Colors can be a problem.  When I first started Quattro Pro, I was
running in mono mode, and I couldn't see anything.  I switched to CGA and it
worked fine.  Other DOS programs may have similar difficulties.


        I have used IBeM, a shareware software-only emulator.  It boots much
faster than the bridgeboard, but of course, runs much slower.  The IBeM
documentation claims approximately XT speed on a 3000/25 setup such as
mine.  (I could never run Norton's SI -- I got a division by zero error,
due, I presume, to IBeM's not implementing the real-time clock.  I wonder
what the numbers are like on CrossPC.)


        The only bugs I've found were in the documentation, as I mentioned
in INSTALLATION.  Of course, there are many things I haven't tried yet.


        I've never contacted the vendor for support, but I did send email to
Dave Haynie once.

        I'm not affiliated with Commodore in any way, but I'm thinking about
buying stock and joining the "Oust Irving Gould" campaign.


        There is a one year warranty on manufacturing defects; it is


        The bridgeboard does everything it purports to, so far as I can tell.
As I said before, I plan to post followups when I expand the PC side of my

        I would enjoy hearing from other bridgeboard users, especially those
who have installed expansion boards or other peripherals, *or* alternate
operating systems.  My email address is