Obligement - L'Amiga au maximum

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David Brunet



Hardware: A2386SX
(Article written by Matt Guthrie and excerpt from comp.sys.amiga.reviews - July 1993)

Brief description

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).

Author/company information

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

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

List price

$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).

Special hardware and software requirements


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 8MB).

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 bridgeboard?)


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

Machine used for testing

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 in.

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.com, keyboard.sys, emm.sys, and bbsetup.com.


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 review.)

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.

Likes and dislikes

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

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.

Comparison to other similar products

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.

Vendor support

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 non-transferable.


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 Amiga.

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 m.guthrie@bull.com.

Copyright notice

This review is freely distributable, as long as the content remains unchanged.

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