Bridgeboard Frequently Asked Questions

 
What is a Bridgeboard?
A Bridgeboard is an Amiga specific card with a 8088
or X86 series CPU that allows running PC software as well as sharing of the
resources of the Amiga (monitor, disks, keyboard and mouse, etc...) with the
PC.
What are the Bridgeboards?
       A2088 XT Bridgeboard:
This was the first Bridgeboard made. It is based off the Intel 8088 CPU, which
is an 8-bit version of the 8086 CPU found in most XT compatible computers.
Fully compatible with the 8086 it will run any software for the XT class of
machines. The A8088 bridgeboard came standard with a 4.77mhz CPU, 512K of RAM,
Monochrome/CGA display and a 360K 5.25" disk drive.
       A2286 AT Bridgeboard:
This was the second Bridgeboard that was made. It is based off the Intel 20286
chip found in any AT compatible computer system. It came standard with an 8mhz
CPU, 1mb of RAM, Monochrome/CGA display and a 1.2mb 5.25" disk drive.
       A2386SX Bridgeboard:
This was the last Bridgeboard made. There are three versions of it, all are
based off the 80386SX chip. This chip differs in that it is internally a
32-bit chip, but it only has a 16-bit bus (like the 68000). All A2386SX
Bridgeboards came standard with a 16mhz/20mhz/25mhz CPU, 1mb of RAM (up to 8mb
on board), Monochrome/CGA graphics, and they could use your Amiga 3.5" disk
drive.
A2088 XT Bridgeboard Information
Jumper and socket locations:
---------------------------------------------------------------------
|                                                                   |
|                                               J2                  |
|                                                                   |--
|                                                        ----     ::| |
|                                         ------------   |21|     ::|F|
|                                         |   8087   | J1|43|     ::|L|
|                                         |   FPU    |   |65|    J::|O|
|                                         ------------   ----    3::|P|
|                                         ------------            ::|P|
|                                         |   8088   |            ::|Y|
|                                         |   CPU    |            ::| |
|                              --------   ------------              |--
|                              | BIOS |                             |
|                              | ROM  |                             |
|                              --------                             |
|                                                                   |
|                                                                   |
---------------------------------------------------------------------
     |      Zorro Connector      |               |      XT       |
     ----------------------------               -----------------
Jumper Information.
    J1: Default video display. 
      1. Monochrome: Pins 4-6 and 3-5 (default). 
      2. Color 40x25: Pins 4-6 and 1-3. 
      3. Color 80x25: Pins 2-4 and 3-5. 
      4. None: Pins 2-4 and 1-3. 
    J2: Connector for PC speaker.
    J3: Internal 360KB floppy drive connector.

Technical Specifications:
    Function: Provides an IBM-PC/XT compatible coprocessor system for a computer in the A2000, A3000
         and A4000 series.
    Processor: 8088
    Clock Speed: 4.77mhz
    Coprocessor: Optional 8087 FPU supported
    Memory: 512K supplied
    Floppy Disks: Supports up to 2 standard PC floppy disk drives: 
        5.25" Drives: 360KB (Comes standard with 360KB drive) 
        3.5" Drives: 720KB (Uses Amiga external floppies drives on the external floppy connector) 
    Card Type: Uses both Amiga bus and PC ISA bus. Occupies one of the two combined positions.
    Video Display:
      1. IBM-PC MDA Monochrome 80x25 text mode.
      2. IBM-PC CGA Color text (80x25 & 40x25) and graphics (640x200x2 & 320x200x4 color) modes
         supported in Amiga windows simultaneously.
    Keyboard: IBM-PC/XT keyboard emulation using the Amiga keyboard
    Parallel Port: IBM-PC compatible Centronics port emulation using the Amiga's parallel port.
    ROM: 16KB XT-compatible BIOS
    Interprocessor Communications: 128K of shared memory, ability for PC to interrupt Amiga and
                                    vice versa.
 
A2386SX Bridgeboard Information
Jumper and socket locations:
---------------------------------------------------------------------
| The  -------------        J101   ----- -----                      |
|Bridge|    ZIP    |               |   | |   |                J515  |
|      |    RAM    |               |386| |FPU|                      |--
|      |  Sockets  |               |   | |   |                      | |
|      -------------               ----- -----               J501   |F|
|                                                            J502   |L|
|                                                                   |O|
|                                                                   |P|
|                                                                   |P|
|                                                     J506          |Y|
|                                                                   | |
|                                       J601                        |--
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
|                                                                   |
---------------------------------------------------------------------
     |      Zorro Connector      |  |    AT    | |      XT       |
     -----------------------------  ------------ -----------------
Jumper Information.
    J101: (ON) Enables Pipeline mode. If removed, Pipeline mode is disabled.
    J501, J502: (1-2) Select the type of internal drive. Pins 1-2 for PC drives, Pins 2-3 for Amiga.
                      Both jumpers must be set the same.
    J506: (ON) Enabled on-board PC floppy drive access. If removed, the floppy drive controller DMA
               is disabled.
    J515: (1-2) Select which Amiga drive is used as the shared drive. Pins 1-2 for DF0,
                Pins 2-3 for DF1
    J601: (ON) Enables on board PC floppy drive access. 
Default positions in parentheses. The user should only need to change J501, J502 and J515.
Expansion Issues:
Here are memory locations, I/O ports and interrupts to avoid when adding PC peripherals.
Memory Locations to avoid:
 A0000 to AFFFF: If Janus handler load segment is set to A0000 in PCPrefs.
 B0000 to B1FFF: If Monochrome display adapter emulation is enabled in PCPrefs.
 B8000 to BFFFF: If Color display adapter emulation is enabled in PCPrefs.
 D0000 to DFFFF: If Janus handler load segment is set to D0000 in PCPrefs.
I/O Ports to avoid:
 000-00F            0F0
 0C0-0DE            0F1
 060                0F4
 061                0F5
 062                0F8-0FE
 064                2Fx
 070                37x
 087-08F            3Bx      If MDA emulation is enabled.
 092                3Dx      If CGA emulation is enabled.
 0E8-0EF            3F0-3F7  If on-board floppy access is enabled.
Interrupts to avoid:
 IRQ0
 IRQ1
 IRQ2
 IRQ3
 IRQ6  If on-board floppy access is enabled.
 IRQ7
 IRQ8
 IRQ13
Technical Specifications:
    Function: Provides an IBM-PC/AT compatible coprocessor system for a computer in the A2000, A3000
         and A4000 series.
    Processor: 80386SX
    Clock Speed: 16mhz, 20mhz or 25mhz
    Coprocessor: Optional 80387SX FPU supported
    Memory: 1MB supplied (expandable to 8MB)
    Floppy Disks: Supports up to 2 floppy disk drive from the following:
      1. One PC-only external drive (3.5" or 5.25")
      2. Two PC-only internal drives of same computer type (PC or Amiga), 3.5" 1.44MB PC drive, 3.5"
         720KB/880KB PC or Amiga drive, 3.5" 880KB/1.76MB dual-speed Amiga drive, 5.25" high density,
         or 5.25" low density.
      3. One shared 3.5" Amiga drive
    Card Type: Uses both Amiga bus and PC ISA bus. Occupies one of the two combined positions.
    Video Display:
      1. IBM-PC/AT MDA Monochrome 80x25 text mode.
      2. IBM-PC/AT CGA Color text (80x25 & 40x25) and graphics (640x200x2 & 320x200x4 color) modes 
         supported in Amiga windows simultaneously.
    Keyboard: IBM-PC/XT keyboard emulation using the Amiga keyboard
    Parallel Port: IBM-PC/AT compatible Centronics port emulation using the Amiga's parallel port.
    ROM: 64KB AT-compatible BIOS
    Interprocessor Communications: 128K of shared memory, ability for PC to interrupt Amiga and 
               vice versa.
    Power: 2.5 amps @ 5.0V
A2286 AT Bridgeboard Information
Jumper and socket locations:
---------------------------------------------------------------------
|Main       J4                --------------------------------------|
|Board                        |Sandwich         J                ::||
|                             | Board           1               F::||
|                             |                 3               L::||
|                             |                    J      J     O::||
|                             |                    1      6     P::||
|                             |                    4            P::||
|                             |     - - - - - -                 Y::||
|                             |     |  80287  | -------          ::||
|                             |     |   FPU   | |O-ROM|            ||
|                             |     - - - - - - -------            ||
|                             |                 -------            ||
|                             |                 |E-ROM|            ||
|                             |                 -------            ||
|                             |                 J5                 ||
|                             |                                    ||
|                             --------------------------------------|
---------------------------------------------------------------------
     |      Zorro Connector      |  |    AT    | |      XT       |
     -----------------------------  ------------ -----------------
Jumper Information.
    J4: (1-2) Internal floppy disk controller. Pins 1-2 for enabled, Pins 2-3 to disable.
    J5, (2-3) RAM configuration. Pins 1-2 for 640K, Pins 2-3 for 1024K.
    J6: (2-3) Internal disk type. Pins 1-2 for PS2 Mode, Pins 2-3 for AT Mode.
    J13: Lithium battery connector. To store BIOS setup.
    J14: (1-2) Default video mode configuration. Pins 1-2 for Mono, Pins 2-3 for Color. 

Technical Specifications:
    Function: Provides an IBM-PC/AT compatible coprocessor system for a computer in the A2000, A3000
              and A4000 series.
    Processor: 80286
    Clock Speed: 8mhz
    Coprocessor: Optional 80287 FPU supported. Located under sandwich board.
    Memory: 1MB supplied
    Floppy Disks: Supports up to 2 standard PC floppy disk drives: 
        5.25" Drives: 360KB, 1.2MB (Comes standard with 1.2MB drive) 
        3.5" Drives: 720KB, 1.44MB 
    Card Type: Uses both Amiga bus and PC ISA bus. Occupies one of the two combined positions.
    Video Display:
      1. IBM-PC/AT MDA Monochrome 80x25 text mode.
      2. IBM-PC/AT CGA Color text (80x25 & 40x25) and graphics (640x200x2 & 320x200x4 color) modes
         supported in Amiga windows simultaneously.
    Keyboard: IBM-PC/XT keyboard emulation using the Amiga keyboard
    Parallel Port: IBM-PC/AT compatible Centronics port emulation using the Amiga's parallel port.
    ROM: 16KB AT-compatible BIOS
    Interprocessor Communications: 128K of shared memory, ability for PC to interrupt Amiga and
                vice versa.
Janus versions
All Bridgeboards use a library system called Janus to handle communication
between the host  Amiga computer and the Bridgeboard itself.  The latest
version of Janus is version 2.1 which only came standard with the A2386SX
Bridgeboard.  Janus 2.1 will work with the A2088 and A2286 Bridgeboards. 
Features in Janus 2.1 over v2.0 are:
 - Windows 3.x compatible display and mouse drivers.
 - New ARead and AWrite utilities, more options and wildcard support.
 - Autoload feature which willstart up the Amiga side service when the
   PC requests it (AMouse, ATime,etc).
 - Install utility that will set-up hardfiles, install enforcer, etc.
 - Workbench 2.0 compliant interface.   
 
Compatibility problems / Bridgeboard Problems
The best way to think of the Bridgeboard is as an IBM on a card stuck in your Amiga. 
The only parts of the IBM that are being emulated are the keyboard, mouse, hard drive, and display.
Even for some of these they can be replaced by the real thing.  For example its possible
to install a Microsoft mouse, or a I/O card with a real hard drive or a VGA card.  Despite all of that, 
that, I'm sure that you'll probably find some software or hardware that doesn't like the Bridgeboard.
Below are some problems and their fixes (if they have one):
DosShell turns to garbage when I select a graphics display.
This is a fault of the AMouse driver. You must either run DosShell in a text display or use a
real Microsoft compatible mouse.
The AMouse driver doesn't operate with program 
The AMouse driver isn't that great under DOS, your only fix for this is to install a real Microsoft
compatible mouse on the Bridgeboard.
How do I install the AMouse3.drv in Windows?
The AMouse3.drv (comes with Janus 2.1), will operate under Windows 3.0 and 3.1, however you have to 
install it manually.  First installWindows, then enter your Windows directory and edit the file called 
"SYSTEM.INI".Find the line called "mouse.drv=#####" and set it to "mouse.drv=amouse3.drv". Lastly,
put a copy ofthe AMouse3.drv in the "system" directory found in your "windows" directory.
My hardfiles don't work.
Most common problem is that you have an 68030/040 CPU. With these CPUs you need to either:
- Turn the CPU DataCache off or
- Install the Enforcer utility (if your CPU has an MMU)
Always getting a message that Janus.library cannot be found.
This could be caused by a couple of different things.
- You don't have the "binddrivers" statement in your startup-sequence.
- You don't have the "Janus.library" in the Expansion drawer on your boot drive.
- You have all 8 megabytes of autoconfig RAM used up (can only have 6 megabytes of autoconfig RAM)
My hardfile access is very slow.
 If you increase the buffers on the hard drive that has the hard file on it your access time will
improve.  You need to add A LOT of buffers to make it faster (like 800 to 1000 buffers).  Also,
hardfile speed is based on the size of the hardfile, a large hardfile is slower than a smaller one.

 
Bridgeboard Utilities
Here are a few programs that will make life using your Bridgeboard a bit easier.
AmiCDex (misc/emu/AmiCDEx21.lha): This program will let you use a CD-Rom drive that is connected
to your Amiga on your Bridgeboard.
Bridgeboard CPU Upgrade (misc/emu/BBCpuUpgrde1_0.lha): This contains information about upgrading
A2386SX Bridgeboards with different 486 clip-on modules.
Janus Tools (misc/emu/JanusTools.lha): This package contains two different utilities.The first
one, is a replacement interface for A2386SX Bridgeboards with a VGA card.  It lets you access
all the different features of Janus from one interface, and will even run a auto-switch box
(see below). The second utility is the great one, it will let you use an Amiga hard drive
partition as a PC hard drive. It is much faster than  a hard file and easy to set up as well.
This partition utility will run with any Bridgeboard, as long as you have Janus v2.1
BBSwitch (misc/emu/BBSwitch1_0.lha): This is the hardware device that allows you to switch between
the Amiga display and the PC display on the same monitor. It works very well with the Janus Tools
package.
CDJanusTools (CDJanusTools.lha): This document explains how to set up the Amiga and Janus Tools PC
partition to be able to access the files from the Amiga side using CrossDos.
@endnode
 
Other Frequently Asked Questions
Q: Is there a video driver that allows me to display the PC screen on my AGA machine/graphics
   card?
A: There is no such driver, and probably will never be as the amount of data that would have
   to be transfered from the PC to the Amiga would probably make the display update very slow.
Q: Can the A2386SX Bridgeboard be upgraded to a higher processor?
A: Yes, it can be upgraded all the way up to a 486SLC at 75 MHz. See @{"utilities" link utils 0} for more info.
Q: Why are there files missing in my setup?
A: Appendix E of the Bridgeboard manual lists all the files that are supposed to be in the
   appropriate directories, but in page 4-24 of the Bridgeboard manual, the missing command
   'XCOPY A\DOS C:\JANUS' has to be executed in order to copy all the required files.

16-12-2000