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geekhack Community => Keyboards => Topic started by: the_buff on Mon, 18 July 2011, 20:22:02
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I was cleaning a Dolch Pac 64 keyboard and noticied a dip switch on the PCB.
[ATTACH=CONFIG]21344[/ATTACH]
Anyone know what it's for?
Also, any recommendations of a place with a large assortment of computer cables and connectors for sale? (e.g. every size shape color and style imaginable)
Thanks
*UPDATED WITH PHOTO
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I can't help with the switch, but for cables http://www.cablestogo.com has pretty much everything.
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*updated with photo
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In all likelihood it's an AT/XT selection switch, as Dolch used off the shelf 'generic' chassis which were used for many systems of varying ages (I have one such 'generic' unit in 286 form - if there were 8086 or 8088 units, these would have required an XT compatible keyboard)
This is a guess - an educated guess, but still a guess.
Which direction would be which? In the ON position, as it is now, it worked on the Dolch. ON is AT and 1 would be XT? The dolch unit is running Windows 95.
Also, not ever having fiddled with one of these, this is the kind of thing where I should UNPLUG the keyboard and then flip the dip switch? Or would there be no problems if I flipped it when it was hot?
Your educated guesses are very welcome.
Thank you.
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Can you post a picture of the opposite side of the PCB?
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Can you post a picture of the opposite side of the PCB?
Fair warning the photo is larger than usual for a forum pic. If a different angle is needed let me know.
[ATTACH=CONFIG]21537[/ATTACH]
I suspect you paid far more than any conceivable notion of the value though (based on current Dolch trends), so I'd advise you not to do that quite yet :)
Hehe...It was $89 shipped, and everything worked. More than I've spent on eBay in one shot, but less than I've paid for a new keyboard. ;)
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Hm. Definitely changes the route of some signals as they go to the motorola chip. XT/AT switch makes sense, but let me find HaaTa to see how that matches his experience with these type switches. 3 lines difference into the controller, not sure if that adds up to XT/AT toggle.
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Heh, Oqsy getting me to post, :P.
Well, without looking up the chip specs (pin out)...it might actually be an ON switch, or at least providing some sort of Vcc to the Motorola chip. Give me a few minutes, I'll go try to find a spec sheet for Motorola chip.
Edit:
Taking a closer look, may not be Vcc after all. The switch connects some external wire to the Motorola chip. I can't see the wire because it's hidden behind other wires, but it's connected to the same trace as "C4" (not at C4, but close by, no lable for it).
My time being limited today, haven't been able to find a data sheet for the controller. As that could be a big hint, though I suspect it's just an input of sorts for something, and the wire it's connected to will probably give a better indication.
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Edit:
Taking a closer look, may not be Vcc after all. The switch connects some external wire to the Motorola chip. I can't see the wire because it's hidden behind other wires, but it's connected to the same trace as "C4" (not at C4, but close by, no lable for it).
I can oblige if I had any idea what you were talking about. :)
I think I understand but I labled a picture so that maybe you could give me a better idea. [EDIT: The labels don't show up nearly as well as I thought they would. So you have to open the image and actually zoom in]
[ATTACH=CONFIG]21566[/ATTACH]
This shows the wires a little better.
[ATTACH=CONFIG]21567[/ATTACH]
Thanks!
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Heh, np. Looks like the black wire. Where you labelled "I".
Where does that black wire connect to?
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Heh, np. Looks like the black wire. Where you labelled "I".
Where does that black wire connect to?
It connects to a female 4-pin jack (RJ9 or 4P4C). The cord to the computer plugs into that jack.
The black wire is pin 1 (or pin 4 depending on how you count), not sure if that tells you anything else.
:)