Where to Buy Alphanumeric Keyboard Matrix?

[Martin_H]

I have a project in flight to add a PS/2 keyboard using a microcontroller to convert the scan codes to ASCII, but that's a bit overkill since I have 16 free IO pins on my 6522's to scan a keyboard matrix. But I haven't seen bare keyboards for sale. So I'm not sure where to get one, aside from taking apart an existing PC keyboard, or buying an old computer off eBay and using its keyboard .

I know that there are premium keyboards available as parts, but these are over $100, and taking apart an existing keyboard would be cheaper. A used TI 99/4a without a power adapter can be purchased from around $18 which might yield other parts besides the keyboard (specifically the TMS9918a and RAM), so that's an option.

Any ideas for sources of keyboards?

[BigEd]

A USB keyboard can be had for £10 or so - I've never opened one up, but it's not too expensive to do that, and see if you can unhook the controller chip and attach your I/O lines to the matrix.
Looks like it should be feasible:
http://modelrail.otenko.com/electronics ... ontrollers

[barrym95838]

If you decide to go the TI 99/4a route, please be aware that not all of their keyboards were created equal.

http://atariage.com/forums/topic/238620 ... ey-screen/

Mike B.

[nyef]

... Why not just use two of those 6522 pins to bit-bang a PS/2 keyboard interface?

[Martin_H]

nyef wrote:

... Why not just use two of those 6522 pins to bit-bang a PS/2 keyboard interface?

I may try this as well. I've seen a 6502 library that does this, although it takes a fair bit of resources to manage the keyboard and convert scan codes to ASCII.

The reason I am starting with the AVR is that the scan code to ASCII firmware is already available online, so it's mostly a wiring exercise. I can run the characters in through the console or bit bang via the 6522.

[commodorejohn]

Yeah, bit-banging for basic I/O is not, shall we say, an optimal solution.

Anyway, buying an inexpensive keyboard and taking it apart isn't a bad approach, but it might require some work, as a lot of keyboards just run the matrix lines right into the on-board controller. You could probably still hack it up, though.

Alternatively, if you don't need a specifically PC-style layout, the Landel Mailbug "email appliance" has a rather nice little compact keyboard that has a plain matrix output to whatever is on their mainboard, so that should be dead simple. No idea what the pinout is on it, though. You can get 'em for ~$25 on eBay. Also gets you an 80x6 character LCD display, if you can figure out how to hook it up to a suitable controller.

[BigDumbDinosaur]

This is a little off-topic, but I seem to vaguely recall someone figuring out how to adapt a PC-AT style keyboard to a Commodore 128D. Seems as though he didn't like the C-128's keyboard layout and action.

[whartung]

What an interesting device.

Has anyone torn one open? (Not to completely derail the thread here.)

[Dr Jefyll]

> What an interesting device

Indeed!

[commodorejohn]

whartung wrote:

What an interesting device.

Has anyone torn one open? (Not to completely derail the thread here.)

Yeah, it's not much to look at on the inside, just a single board with a bunch of SMT components and a little fluorescent tube for the backlight hanging off it. I think it's a Coldfire something-or-other at the core. But the LCD's decent, and the key action is quite pleasant for a little compact keyboard.

[cbmeeks]

As a collector of vintage computers, I would like to politely ask you not to gut a TI unless it's reversible or you manage to find one that is incomplete (already gutted).

You wouldn't pull the steering column out of a Model T so that it could hang in a bar would you?

Having said that, I also plan on using a TI keyboard for a project. BUT, I own 5 different TI's and this one is my "parts" TI. It doesn't work and was already broken when I got it.

Anyway, just thought I would mention that...

[Martin_H]

Not to worry, I was planning to buy a for parts or repair one off eBay. But for now I'll stick with the PS/2 keyboard and bit bang using Daryl's library: http://sbc.rictor.org/pckb6522.html

If I decide to try using the matrix technique I may see about removing an old laptop keyboard which may work.

[malcnorth]

I am doing something similar and have opted to use a VIC-20/C64 keyboard. The advantages of this is that it's already wired to connect to a 16 bit I/O port. The keyboard matrix is also widely available on the net.

[Martin_H]

Part of my reason for looking for an old keyboard is that the good ones were mechanical and had a really satisfying feel. Most modern keyboards aren't nearly as satisfying to type on unless you spend a fortune. I already have TI 99/4a and it's keyboard is particularly nice, although a bit small.

[malcnorth]

Martin_H wrote:

Part of my reason for looking for an old keyboard is that the good ones were mechanical and had a really satisfying feel. Most modern keyboards aren't nearly as satisfying to type on unless you spend a fortune. I already have TI 99/4a and it's keyboard is particularly nice, although a bit small.

No problem, ultimately comes down to what you like/are used to. Vic and C64 are 1980 vintage so I wouldn't call them modern! but they aren't switches if that's what you mean. I can't remember the last time I saw a keyboard with a switch.