Atari-type Joystick Ports for the Elk (Beeb)

for bbc micro/electron hardware, peripherals & programming issues (NOT emulators!)
Post Reply
User avatar
CharlesMouse
Posts: 116
Joined: Sat Jul 24, 2010 10:59 am
Location: Nowhere
Contact:

Atari-type Joystick Ports for the Elk (Beeb)

Post by CharlesMouse » Fri Aug 07, 2015 1:31 pm

Hmm,
A thought arose in while perusing the forum. While analogue controllers are great for the likes of Elite sometimes I want to use a digital joystick. Maybe I've actually got a friend ( :shock: ) for some two player action but not a good enough friend to want to get that close clustered round the keyboard...
...Yes, there are adaptors but I wonder if there's an easy way to get what I want..?

Maybe I can I take a leaf out of "Uncle Clive's" el-cheapo approach to computer design and wire a couple of D-Type connectors right in to the keyboard matrix..? As such a scheme will be "key-mapped" I should get compatibility with many games for free, so to speak.

I think I'm going to have a go. I should be easy enough to insert an extra pin-header between keyboard and PCB for a plug 'n play approach. The tricky bit is where to mount the connectors? On a Beeb / Master there's loads of room but on the Elk options are limited.

I shall post piccies of progress, but before I begin this is such a simple mod (electrically) I'm surprised I can't find any reference to it having being done before...
...am I missing an improtant "gotcha"?
Charlie.

Are you pondering what I'm pondering? The Qube RiscOS Server

User avatar
jgharston
Posts: 3806
Joined: Thu Sep 24, 2009 11:22 am
Location: Whitby/Sheffield
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by jgharston » Fri Aug 07, 2015 1:34 pm

From the layout of the keyboard matric, the simplest digital joystick interface would be the cursor keys plus copy/return/delete as they are all in the same column. For anything else it would be fiddly as you'd be trying to use a common-pole device to control keys in a matrix that have no common poles.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

poink
Posts: 963
Joined: Tue Mar 01, 2011 10:27 am
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by poink » Fri Aug 07, 2015 1:55 pm

CharlesMouse wrote:...am I missing an improtant "gotcha"?
The 'gotcha' would be that many games support the analogue sticks, but don't allow key remapping.

Prime
Posts: 2822
Joined: Sun May 31, 2009 11:52 pm
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by Prime » Fri Aug 07, 2015 2:10 pm

poink wrote:
CharlesMouse wrote:...am I missing an improtant "gotcha"?
The 'gotcha' would be that many games support the analogue sticks, but don't allow key remapping.
Yes I always found that a pain in the arse :) as I find the default keys for some of the games a little unfriendly.

A Device that had a microcontroller and a crosspoint switch would allow re-mapping if done right....and no I'm not offering to do it!

However I believe that the BBC uses a potential divider (like the Dragon does) so it should be possible, to make a converter with some simple electronics.

Cheers.

Phill.

User avatar
1024MAK
Posts: 9612
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by 1024MAK » Fri Aug 07, 2015 2:18 pm

Prime wrote:However I believe that the BBC uses a potential divider (like the Dragon does) so it should be possible, to make a converter with some simple electronics.
It is. Uses some transistors and resistors. Details are on his forum somewhere...

Mark

User avatar
roland
Posts: 3583
Joined: Thu Aug 29, 2013 8:29 pm
Location: Born (NL)
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by roland » Fri Aug 07, 2015 4:00 pm

BITD I made this:

http://acornatom.nl/atom_nieuws/1989/nr2/19892034.htm

In short, you create an electronic switch parallel to the most used keys in games:

Z, X, / and : The fire button goes to the return key. A big advantage is that the software needs no modification.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

poink
Posts: 963
Joined: Tue Mar 01, 2011 10:27 am
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by poink » Fri Aug 07, 2015 7:42 pm

It doesn't seem to say which IC they're supposed to be, but if anyone's having a go at it, I'd be pretty certainly they're 4066 (quad analogue switches).
Prime wrote:like the Dragon does
I found this for the Dragon 32, but I'm a little concerned about what happens if up and down (say) are both closed. I think the solution is probably a sprinking of diodes (4, one for each analogue switch).

If you're just wanting a digital stick, then, on the Beeb at least, I'd be pretty tempted to wire up a couple of reasonable arcade sticks to the analogue port (I think you'd also be be needing the diodes for the same reason).

User avatar
roland
Posts: 3583
Joined: Thu Aug 29, 2013 8:29 pm
Location: Born (NL)
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by roland » Fri Aug 07, 2015 10:44 pm

poink wrote: It doesn't seem to say which IC they're supposed to be, but if anyone's having a go at it, I'd be pretty certainly they're 4066 (quad analogue switches).
That's correct, I used two 4066. It's documented in the accompanion text on the page before the diagram.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

User avatar
1024MAK
Posts: 9612
Joined: Mon Apr 18, 2011 4:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by 1024MAK » Fri Aug 07, 2015 11:16 pm


User avatar
CharlesMouse
Posts: 116
Joined: Sat Jul 24, 2010 10:59 am
Location: Nowhere
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by CharlesMouse » Sat Aug 08, 2015 7:53 am

:) Thanks chaps for the positive and helpful responces.

@ Roland:
Yes, that's the kind of scheme I had in mind... Although I was thinking of lashing up something a bit more direct 'n nasty, possibly with the odd diode. :?
Charlie.

Are you pondering what I'm pondering? The Qube RiscOS Server

User avatar
roland
Posts: 3583
Joined: Thu Aug 29, 2013 8:29 pm
Location: Born (NL)
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by roland » Mon Aug 10, 2015 6:27 pm

I have found my Elk with the Atari type joystick. It's not the very best way to implement it but it worked:
image.jpg
image.jpg
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

User avatar
CharlesMouse
Posts: 116
Joined: Sat Jul 24, 2010 10:59 am
Location: Nowhere
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by CharlesMouse » Tue Aug 11, 2015 4:40 pm

Hi Roland,
Yes that's the idea I was going for - although I hope to do something to emulate a factory look:

When I get round to this I may test the concept with a Beeb or Master first (more room). I can see doing this with an Elk is going to be tricky...
...To manage such an illusion I'll need to mount preferably two Atari-type ports on their own board lower down on the power connector side to match the positioning of the ports on the other side. Of course that means the PSU board is exactly where I don't want it to be... If I can get away with mounting that on standoffs to allow the ports to go under it that's all good. Shame Acorn went for round holes in the case on the other side - replicating that look won't be easy.
Charlie.

Are you pondering what I'm pondering? The Qube RiscOS Server

User avatar
Wookie
Posts: 342
Joined: Sat Aug 27, 2005 10:06 am
Location: Lost in a fog of PSU capacitor smoke
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by Wookie » Fri Aug 14, 2015 5:25 pm

roland wrote:Image
I see yours has the RF shielding, does it make much of a difference ? I remember you could tell how hard your electron was working by the interference on any nearby radio.
cheers Wookie
Overclocked StrongARM RiscPC + Viewfinder
Overclocked Arm3 8MB A310 + vidc extender
BBC Master with Matchbox CoPro
BBC B+ 64K
My original Electron from 1985 with Slogger MasterRam/Turbo,AP1,AP2 rom, AP3+4 & New AP6

User avatar
roland
Posts: 3583
Joined: Thu Aug 29, 2013 8:29 pm
Location: Born (NL)
Contact:

Re: Atari-type Joystick Ports for the Elk (Beeb)

Post by roland » Fri Aug 14, 2015 6:06 pm

Well, I never heard my Electron working on the radio but I do remember that the unshielded Atom was audible on the radio. Since one week I have an unshielded (uk) Electron so I can test if it makes a difference.
FPGAtom: 512 KB RAM, Real Time Clock and 64 colours
MAN WOMAN :shock:

Post Reply