Sunday, November 16, 2014

First steps towards a C65GS laptop

From the outset I had thought about what form-factor the C65GS would have as a computer.

Basically it was a question of whether to make it something that looks and feels like the original C65, or whether to make it into a laptop.

Nostalgia said that something that looked like the original would be nice.  However, the realisation that being able to create 3D-printed or injection moulded replicas of the C65 case would be extremely expensive put a dampner on that idea.

Also, as I got working on the C65GS I found myself increasingly desiring a portable computer - both for taking places to show and so that it could be used for some light general productivity.

So I have been thinking about how to do this, and taking a look at what some other very clever people have done in the past.  The most interesting one is this laptop commodore 64, made using original parts.  This is interesting to me, because it was created using a real C64 keyboard, and he fabricated the case parts himself.  While I don't plan to use a real C64 keyboard for mine, I do intend to use the real C65 keyboard I bought on ebay recently.  Fortunately, the C65 keyboard already has the function keys moved to the top, and so is narrow enough to be used unmodified in a 15" laptop.

More of how Ben fabricates custom cases like this is covered in another post of his.

However, before I get to that point, I need to work out exactly what I intend to cram into the thing.

Obviously the Nexys4 FPGA board needs to go in.

I have already sourced 4 x 30Wh LiFePO4 rechargeable batteries, sufficient to skirt the air-line limits in several countries, but also enough to run a bright screen for a few hours at least.  I'll need to find a charger circuit for them, perhaps something like this that should allow me to put 15.6V in and charge the batteries.  The output from the batteries then can be fed into one of these to provide enough 12V for a 15" LCD panel, and a very similar one of these to provide ample 5V for the FPGA board and related circuitry.

I had originally looked for a 13" 1920x1200 panel, but those are rare as hens teeth, so have settled for a 15.4" one.  After a bit of hunting it looks like this panel and this LCD driver kit should work together, and will accept the 1920x1200 60Hz VGA signal from the FPGA board.

This leaves the joystick/keyboard/IEC serial and other ports, plus speaker driver PCB as the great unknown in terms of internal components. However, even without that PCB, I am starting to have a think about how things would be arranged in the eventual case.

I will probably use a similar approach to Ben's portable C64, and have an external lead that connects the panel in the top half of the case to the lower half.  Because I am using VGA connections, I am contemplating making the cable easily removable, at least from one end, so that it is easy to connect to an external monitor, or indeed use the 15" panel as a VGA display for something else when required.

I might buy a panel and LCD driver kit just to get my head around getting those working together and with the FPGA board, and then incrementally work on everything else as I get the opportunity.