Tag: Amiga

Introduction

This post is a step-by-step tutorial for installation of the IndivisionAGA MKII hardware into an Amiga 1200 Desktop machine.  The target Amiga already has a FastATA fitted and there are some extra (easy) steps that will be necessary in order to allow these two peripherals to be fitted together in the machine at the same time.  This tutorial will also cover these steps.

What you will need

In order to complete a working installation of the IndivisionAGA MKII you will require the following:

1. An Amiga 1200 Desktop (or towered – the steps will be similar) Computer.
2. An IndivisionAGA MKII peripheral from AmigaKit.
3. A phillips-head screwdriver for removal of the A1200D enclosure.
4. A couple of 40-way DIL sockets (See Note 1)
5. A hot-melt glue gun.
6. A piece of thin plastic or other suitable (strong) insulating material approximately 75mmx60mm (See Note 1)
7. An anti-static wrist strap with associated electrical earth connection.

*NOTE 1: These items are only required if you intend to install the IndivisionAGA with a FastATA.

Preparations

Step 1: Remove A1200 top enclosure

In order to complete this procedure you are going to need to take the cover off your Amiga.  If you are unfamiliar with this kind of task then I can offer you the following advice:

Amiga computers were born to be modified.  You are almost committing a crime if you don’t modify it.  Modifying your Amiga comes with the territory, and should form part of the enjoyment you get out of using the machine.  As long as you’re able to be careful, and take things slowly (thinking each stage through as you go along) you shouldn’t encounter any major difficulties.
That said, I do feel obligated to point out that damage to your Amiga is possible if you mess something up.  If you’re already convinced that hardware modification is not your strong point then I would advise you to seek the assistance of a trained technician.  AmigaKit is one company who can offer these kinds of services, and I would highly recommend them to you.

Step 2: Prepare work surface

First, prepare your work top.  My Amiga is a Commodore edition in pristine condition so I like to avoid scratches and scuffs.  If you feel the same then you’re going to want to put something soft down on your work top to prevent cosmetic damage to your machine when you work on it.  The ideal solution would be an anti-static bench mat, but if you don’t have one of these (I didn’t either) then any soft material that does not tend to generate any static should work.  I used an old towel.
Position your Amiga as shown below and then release all of the enclosure screws.

Once you have released all of the securing screws, carefully turn your Amiga back over and then remove the top cover.  Be careful because it is still tethered to the Amiga motherboard via the power/hard-drive LED wiring.  You should be able to flip the top cover over as shown below:

Step 3: Remove the keyboard

The next step is to remove the keyboard.  The keyboard is connected to the Amiga motherboard via a green flat flex-foil cable.  Care must be taken to ensure that the mating connector clasp is released before you try to pull this flat cable out.  In order to release the clasp, pull the top collar upwards on each side until it releases its hold on the flat cable.

Note that the clasp does not fully remove.  It releases its hold on the flat cable and then sits in a released position on the connector housing.  Do not try to remove the clasp from its housing because you will break it!

When the clasp is released it’ll look like the photo below:

 

Once the clasp is released the flat cable should pull free without resistance.  If you feel any resistance then you have not fully released the clasp.
With the cable pulled free you can lift the entire keyboard from its retaining points and set it to one side.

Step4: Remove FastATA

If you have a FastATA fitted then you will need to remove it in order to allow fitting of the IndivisionAGA.  If you don’t have a FastATA then you can skip this stage.

TIP
In my experience the FastATA Gayle connection is not to be tampered with.  Once it has been connected, and it has settled in place, then the less it is disturbed the better.  For this reason I would recommend leaving the Gayle connection alone – you can separate it from the FastATA motherboard by removing the IDC connector.  This will leave you with just the FastATA motherboard to remove from the A1200 ROM sockets.

You need to take great care when removing the FastATA from the A1200 ROM sockets.  The risks, if you’re not careful, are as follows:

• Bending or snapping pins on the FastATA if it is released suddenly at an angle.
• Damaging the FastATA PCB if it is levered against without care.
• Damaging the A1200 motherboard if a sharp instrument is used to lever the FastATA from the ROM sockets.

 

With these potential hazards in mind, use a flat instrument (preferably plastic but I was able to use a flat screwdriver with great care) to gently prise the FastATA from the ROM sockets.  Work on all four corners of the FastATA a little bit at a time, exercising patience.  The retention force of the ROM sockets will initially be very strong because the FastATA will have settled in its connection.  Eventually, after some perseverance and patience, you will be able to release this connection and pull the FastATA free.

 

Step5: Removing the floppy drive

In order to route the IndivisionAGA graphics cable it is better to remove the internal floppy drive.  This item is easily removed by releasing its retaining screws and disconnecting the power and data cables.  Please exercise care when removing the data cable as if it is pulled away at an angle you will bend pins.

Installing the hardware

Step 1: Fitting the IndivisionAGA

The IndivisionAGA main board connects over the top of the Lisa chip.  Make sure you connect it with the orientation shown in the photo below!
When making the connection, press with equal force on the top of the PLCC socket so that it engages Lisa with the minimum angle possible.  It will be necessary to press quite hard in order to complete the connection fully.

Don’t use any tools to force the IndivisionAGA onto Lisa! Use only your hands.

After you’ve fitted the Indivision to Lisa then you will need to route the graphics cable.  Methods are varied but there is unfortunately no ‘perfect’ solution for this as of yet.  My preferred ‘solution’ was to route the cable underneath the floppy drive (hence why I asked you to remove it) and then out of the rear expansion slot next to the mouse port.  I left the DVI connector dangling out of this small access panel, but I secured it later by using the monitor cable fasteners.  Not an ideal solution by any means, but it works.

Step 2: Fitting the ‘riser’ ROM sockets

If you are installing the Indivision with a FastATA, or you plan to use a FastATA in the future, then you will need to fit ‘riser’ sockets into the ROM locations so that the FastATA board will fit over the top of the Indivision.  To do this you will need to fit one pair of 40-way DIL sockets into the existing ROM sockets.  The best type of DIL sockets to buy are the ’round pin’ type as shown in my photo.  You should be able to obtain these from AmigaKit, or you can get them direct from an electronics supplier such as Farnell, e.g. order code 1103855.  Note that the ROM sockets fitted into the A1200 motherboard are 42-pin

but the front two pins are not used.  Therefore you will need to fit your riser sockets so that they sit flush with the back of the A1200 motherboard sockets as shown in the following photo.  Note that some Amiga users report that they prefer to fit two pairs of riser sockets so that the FastATA is hoisted up further, providing even more clearance.  If you order four 40-way DIL sockets then you are free to experiment with this but my experience is that one set of riser sockets provides just enough clearance whilst also ensuring that the Fast ATA does not foul against the keyboard.

Step 3: Preparing the FastATA (insulating) for re-fitting

The FastATA motherboard is mostly through-hole construction, which means that the component connections protrude through to the bottom side of the board.  These protrusions are quite lengthy and as such there is a risk of short-circuit to the Indivision PCB.  In order to guard against short-circuits it is important to insulate the two boards in some acceptable manner.

In my experience I was able to find a piece of strong, thin plastic from an old ring-binder that I trimmed to size.  I then fitted it to the bottom-side of the FastATA using two spots of hot-melt glue.  Hot-melt glue is a good solution because it is easily removed at a later time should the need arise.  Remember that the glue is not there to hold the FastATA board together – it only needs to keep your piece of insulation in place!
I think it goes without saying that the chosen insulation material must be non-conductive.  Plastic is a good choice for this reason.

Step 4: Refitting the FastATA

Once you have settled on a suitable method of insulating the bottom-side of the FastATA from the Indivision you are ready to fit the FastATA back into the ROM socket risers.  Be very careful to ensure that all the pins on the FastATA line up with your riser socket receptacles.  Your FastATA will now entirely fill the ROM sockets because you fitted 40-way sockets into the existing 42-way sockets that are fitted to the A1200 motherboard.  Once you have fitted the FastATA back into the ROM sockets you need to press firmly all around it to ensure a solid connection.  If you end up with a dodgy ROM connection then you will experience all sorts of problems reading/writing to your storage devices so the connection needs to be very secure.

Step 4a: Tie down the Fast ATA?

Some Amiga users prefer to tie-wrap their FastATA motherboards in place to secure it from coming loose after fitting.  I have had mixed experiences with this method and I have not found it to be necessary in a desktop machine, provided of course that your machine is not subjected to transportation.  A modified desktop A1200 is rarely a portable one.
The problem I’ve found with tie-wrapping the FastATA is that it doesn’t quite hold the board down in a manner that is guaranteed to prevent the board from working loose.  In fact, I have had experience of the tie-wraps themselves forcing the FastATA to retreat from its ROM sockets.

The ideal solution to this common problem would be to do some surgery on the A1200 motherboard, removing the existing ‘flat’ type ROM sockets and fitting the ’round’ type (like the ones you’ve used as risers) instead.  This would provide a much stronger connection both electrically and mechanically.  Unfortunately this is not a task for the amateur Amiga tinkerer because it can be very difficult to remove through-hole components from a multi-layer PCB like the A1200 motherboard.  Still, it is possible and a good technician would be able to do it for you if you think it’s necessary.

In my case I found that I was able to complete this work without replacing the A1200 ROM sockets and without tie-wrapping the FastATA in place.

Note that you should strictly limit the number of mating cycles you subject the standard A1200 ROM sockets to.  In practice this means that any time you dismantle your A1200 in the future you should always disconnect the FastATA from the riser sockets, leaving the riser sockets fitted to the A1200 motherboard.  This is because your riser sockets are round-pin and the standard A1200 motherboard sockets are square-pin.  A consequence of fitting a round peg into a square hole is that the connection quality is reduced, and the number of reliable mating cycles is once or twice at maximum before the connection will cease to be mechanically or electrically sound.  If you compromise the standard A1200 ROM socket connection quality then you may be forced to have the ROM sockets replaced (if so use round pin types as described earlier!) so the best advice I can give you is connect the riser sockets once, then never touch them again.

Step 5: Refitting the floppy drive and keyboard

We’re almost done! The floppy drive goes back in the same way that it came out.  Be careful when re-fitting the data cable because it’s all too-easy to miss a set of pins if you are complacent.
Once the floppy drive is re-fitted you can re-fit the keyboard.  Make sure that the mating connector clasp collar is released before you try re-connecting the flex-foil.  If the collar is released then there should not be any resistance when you try to mate the flex-foil to the connector.  Grap the flex-foil with one hand so that it is held in a fully-home position inside the mating connector, and then with your other hand press the clasp collar back down into place.

Step 6: Testing your installation

Murphy’s law says that if you put the cover back on before testing your installation then your work is guaranteed to be a failure.  For some reason as yet unexplained by science, you have to humour Murphy by testing it before putting the covers back on.  If you don’t believe me, try fitting the cover back first and you’ll see what I mean!

In any case, testing first is a good idea.  If there is any unexpected behaviour or problems then you are in a much better position to see what’s going on, and react appropriately, if you have the covers off.
If, for example, you have unwittingly created a short-circuit condition of some kind then you will often see, hear or smell evidence of this if your senses are able to be trained on the gubbins of your equipment.  Reacting to these kinds of issues quickly will save your Amiga.  Blissful ignorance of them (like when the cover is fitted) could damage your equipment beyond repair.  Please take my advice!
If all goes to plan then you should see an Individual Computers logo appear on your monitor within 2-3 seconds of switching on your Amiga.  If, after this, your Amiga boots into Workbench then you will also have confirmed that your FastATA is still working.  If you don’t see the logo, or your Amiga doesn’t boot (or both!) then you will almost certainly have some kind of connection problem.  Go back through your work, checking and re-checking all of the connections and making certain that all the socketted connections are seated firmly in place.

Step 7: Closing

After all is confirmed working Murphy will let you fit the covers back on and all will be well.

I hope you have found this tutorial to be of use.  Please feel free to write a comment.  Constructive criticism is also very welcome – I am an electronics engineer by trade but I certainly do not pretend to know it all!

If you have problems with your installation I may be able to offer some advice.  In that case I would prefer you to comment so that the advice is then available to others, but I also welcome email – please see the ‘contact’ section of my website.

Enjoy, and happy modding!