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Author Topic: Rare Cherry M84 NOS  (Read 2806 times)

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Offline 8_INCH_FLOPPY

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Rare Cherry M84 NOS
« on: Thu, 14 June 2012, 01:52:38 »
See this thread for background info: http://geekhack.org/showthread.php?25877-Unknown-Cherry-switch-the-best-ever-and-I-can-t-find-any-information-on-it&p=486433#post486433
I have a few of these, all in their original bubble wrap. Apparently they built for a laptop Epsom sold in the mid 1980's. They're my favorite switch, but they are missing a controller, and since no one else seems to have one, there's naturally little motivation on the part of anyone else to get these working with a computer. I don't have the digital electronics experience necessary to do it. They are also missing a case, but slapping one of those together shouldn't be too difficult. Any advice on getting some made or building them myself would still be helpful. Here's the deal.

I'm offering 5 of these up for sale under certain conditions:
-$90
-You pay shipping
-If you buy one, you have to give it a review. 'I like it' doesn't count.
-Once you've reviewed it, positive or negative, you can return it undamaged within a month for a full refund, if you so desire.
-If you want to keep it, that's fine too.
-The first person who provides a cheap and easy solution to get one of these on a computer via usb, with all of the keys working gets 3 of these keyboards for free. If several people want to split it, go ahead. Contact me for details.








Keycaps are NOT compatible with other Cherry Keyboards
« Last Edit: Thu, 14 June 2012, 02:04:18 by 8_INCH_FLOPPY »
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Notable Switches I have tried:
black cherry, blue cherry, brown cherry, clear cherry, cherry M84, white alps, black alps, cream alps, Monterey blue alps, Fujitsu Peerless, Gateway2000 rubber dome, Keytronic rubber dome, Model M buckling spring, Model F buckling spring, futaba, black space invader

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HAPPY HUNTING
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Offline hamza_tm

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Rare Cherry M84 NOS
« Reply #1 on: Fri, 15 June 2012, 04:01:18 »
Intriguing

After trying all those switches this is your favourite?
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Offline Soarer

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Rare Cherry M84 NOS
« Reply #2 on: Fri, 15 June 2012, 07:22:58 »
Consider me interested... so what are the switches like then?
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Offline Wildcard

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Rare Cherry M84 NOS
« Reply #3 on: Fri, 15 June 2012, 08:45:34 »
I would be very interested in getting one of these working! Might need a custom controller, but it sounds like fun. PM sent.
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Offline 8_INCH_FLOPPY

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Rare Cherry M84 NOS
« Reply #4 on: Fri, 15 June 2012, 20:16:12 »
Yes, they are the best I've tried. My opinions regarding switches are fairly consistent with popular opinion. I really like Cherry Blues, Buckling springs, etc. The one exception is that I am a fan of *some* of the Fujitsu Peerless keyboards, while most here are not. My daily driver at the moment a nice clean black space invader.

See the thread linked in my first post for a description of what these feel like.

I'm still seriously considering designing the controller by myself, since I want to learn micro-controller programming and digital design within the next couple of years anyway, and I have some friends who could help me. I don't want to bite off more than I can chew, but, now that I think about it, what's the worst that could happen? Is this an unreasonably complex first project for someone who, has just a little bit of C++ programming experience and quite a bit more experience with the analog side of electronics? Where should I start?
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Notable Switches I have tried:
black cherry, blue cherry, brown cherry, clear cherry, cherry M84, white alps, black alps, cream alps, Monterey blue alps, Fujitsu Peerless, Gateway2000 rubber dome, Keytronic rubber dome, Model M buckling spring, Model F buckling spring, futaba, black space invader

================================================
HAPPY HUNTING
================================================

Offline hamza_tm

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Rare Cherry M84 NOS
« Reply #5 on: Fri, 15 June 2012, 20:24:00 »
It is actually pretty complicated. What with key denouncing and chatter and the rest of it!

It's going to be really hard as you need to map every output line in use from the ribbon to say a USB port. If we go into the interrupts/etc it will get really messy.
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Offline 8_INCH_FLOPPY

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Rare Cherry M84 NOS
« Reply #6 on: Fri, 15 June 2012, 20:59:08 »
You're actually making it sound easier, laying out obstacles like that. It's less intimidating when I have a set of challenges to overcome...  I should probably start with a schizmatic. Anyone know where to look?
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Notable Switches I have tried:
black cherry, blue cherry, brown cherry, clear cherry, cherry M84, white alps, black alps, cream alps, Monterey blue alps, Fujitsu Peerless, Gateway2000 rubber dome, Keytronic rubber dome, Model M buckling spring, Model F buckling spring, futaba, black space invader

================================================
HAPPY HUNTING
================================================

Offline hamza_tm

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Rare Cherry M84 NOS
« Reply #7 on: Fri, 15 June 2012, 21:10:23 »
Glad I helped :)
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Offline Wildcard

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Rare Cherry M84 NOS
« Reply #8 on: Fri, 15 June 2012, 23:18:37 »
I'll look around for a schematic if one exists for these Epson boards, sometimes you have to start from scratch. First off you need to flip the board and trace your contacts for each switch. Each switch will obviously close a circuit and you'll need to map it out and document. Once that's done you'll probably want to get a controller like a teensy

Edit: Looks like Igthorn found a schematic, good find.
« Last Edit: Sat, 16 June 2012, 21:46:44 by RiffRaff »
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Offline False_Dmitry_II

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Rare Cherry M84 NOS
« Reply #9 on: Sat, 16 June 2012, 17:13:06 »
Quote from: hamza_tm;614441
It's going to be really hard as you need to map every output line in use from the ribbon to say a USB port. If we go into the interrupts/etc it will get really messy.

Why would you do it that way? That seems like you'd have to figure out whatever signals it is using and communicate exactly the way it was originally designed to.

If I were to bother doing it/learn some of this stuff I'd definitely do the spaghetti wire method. Then you can take advantage of pre-existing projects. Teensy or no.
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Offline Soarer

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Rare Cherry M84 NOS
« Reply #10 on: Sat, 16 June 2012, 18:31:21 »
I can't see anything other than switches on there... how hard can it be?!


Any chance of a higher res version of the 2nd pic showing PCB traces?
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Offline Igthorn

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Rare Cherry M84 NOS
« Reply #11 on: Sat, 16 June 2012, 19:32:52 »
PX-8 documentation

Download PX8_TM_Ch7.pdf and this is in it.
[ Attachment Invalid Or Does Not Exist ] 53033[/ATTACH]
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Offline Soarer

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Rare Cherry M84 NOS
« Reply #12 on: Sat, 16 June 2012, 20:00:05 »
Oh, sweet!

They've put extra diodes on for the modifiers, so they don't ghost. The two shifts are just in parallel though, so they can't be distinguished from each other. Otherwise just an 8 x 9 matrix. Not quite sure why they've put diodes in the rows as well...?
« Last Edit: Sat, 16 June 2012, 20:02:22 by Soarer »
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