Switch attached to CIA in A2000

[McVenco]

I picked up an A2000 today, and I decided to first open it up and give it a thorough cleaning.

I noticed 2 switches in the front of the machine. 1 is a kickstart switch, but the other one is connected to the C301 CIA (the left one). For what I can make up from it, it switches on/off 2 pins, but I really don't know what this could be used for. There are an A2630 turboboard and an A2090 controller inside - could it have something to do with those?

I will try to upload a picture somewhere so it's a bit more clear what I mean...

[McVenco]

Images here, here,  here and here

Sorry for the bad quality, but my digital camera simply sucks. No money for a better one yet :-(

[Castellen]

Hard to say as you can't really see which pins the wires connect to, and you can't see what's happening at the other ends of the wires.

The pictures looks like yellow connects to pin 26 and white to 28, which are both part of the 16 bit data bus.  Doesn't really make any sense.

If you can list which wires connect to which CIA pins and what's happening at the other end, i.e. which wires get joined when the switch is in either position, I might be able to give some suggestions what it's for.


A tip for taking photos when your camera isn't so flash or your photography skills are just crap (like mine) is to use a flatbed scanner.  Produces surprisingly good results.
A bit tricky when you're trying to take a "photo" of something big like a computer though :-)

[McVenco]

I don't have a scanner so I'm afraid I'll have to do with my crappy cam.

As far the pins: like I said there are 2 sockets, and both have cables soldered to them (to the same pins), so I presume either the switch is to switch a combination of the pins, or to switch the pins off.

I don't know what the exact pin numbers are on a CIA, but seen from the top (=backside of the A2000), there are the following wires (all on the left of the socket):
white on pin #13, yellow on pin #15 (bottom socket)
green on pin #13, brown on pin #15 (top socket)

The bottom socket sits on the mobo, while the CIA sits in the top socket.

The wires are connected to a switch:
(the switches moves in direction between rows 123 and 456)

1|4
2|5
3|6

1-connected to 6
2-brown
3-yellow
4-connected to 3
5-white
6-green

I hope this makes it a bit clear.

[alexh]

I am guessing you choose ROMS based on the state of a mouse button.

[delajt]

looks similar to my old (and now-defunkt) A2000 68000 accelerator which made it run at 20mhz. Except mine was black not blue...

Oh the memories of my old BBS are coming back instantly  :-D

[Castellen]

Helps a little bit, but it's not obvious what's happening between the two sockets.
i.e. the white wire is on the pin on top of the green wire; are these two wires electrically connected together, or is there something between the top and bottom socket pins??

[McVenco]

The pins on the top socket have been removed, so I think the switch really was meant to disable the 2 pins of the CIA.

Unfortunately, it seems the sockets were of poor quality and I just snapped off one of the pins from the bottom socket.

The A2000 works fine with the CIA just mounted directly on the mobo, but still I'm wondering what this switch is supposed to do...

EDIT: I doubt it has anything to do with accelerating the 68000, because there's an 68030 board available...

[K7HTH]

McVenco wrote:
EDIT: I doubt it has anything to do with accelerating the 68000, because there's an 68030 board available...

My thoughts exactly.