Proto-Topre infomation collection

[zrrion]

Presently there does not appear to be a proto-topre thread on the wiki, so I'll be trying to gather information in this thread so that a wiki page can be created.

So far, I have identified 2 versions of proto topre in brother typewriters, 2 versions of keycap, and 3 diferent kinds of legends that these boards could come with. So far all of the boards that I have found have been contact based, however, Chyros has found a captivate version, and the contact method changed from dome-over-pcb to membrane at some point.

So, I want to get the ball rolling on any ideas people might have on a timeline for proto-topre, model numbers, photos, all that jazz. I would especially like to establish a firm definition for what proto-topre actually is so that maybe people will stop calling every old rubber dome proto-topre.

[zrrion]

For starters, Proto-topre as I understand it is a slider over dome switch that is 2 way compatible with modern topre switches and caps. Most of the examples that I am aware of come form Brother typewriters and Brother word processors. I only personally own modules from the typewriters, but from what I have seen they use the same caps, although the word processors may have used the capacitive design and the typewriters the contact design but I have no hard evidence for that assumption. I have seen a few dome boards listed as "proto-topre" before but a lot of them look to have been regular dome boards so I do not have any confirmed information for non-Brother proto-topre.

As for construction, all examples that I have seen have used a single part barrel plate that is also the top of the case. I am aware of modern topre boards that have discrete switches that clip into a switch plate, but I have note seen any examples of that in confirmed proto-topre boards. Any info on when this was introduced would be very much appreciated.

[zrrion]

And for a few pictures of what I have.


These are a recent find, and haven't been documented to my knowledge (or if they have it isn't well known.) I'll get to these a bit later.


The underside of these, pretty typical for porto-topre sliders, but they have a small peg on the side that I guess is supposed to avoid a mushy bottom out, but the rubber mat is still underneath that peg so it doesn't really do anything. Do note the felt for silencing. This came out of a typewriter with a fixed daisy wheel and a moving carriage and it was quite loud, so I don't know why they bothered with silencing. Additionally, the ends of the space bar's stabilizing wire have clear shrink tube on them, probably also for silencing.


This is what the domes look like for the dome-over-pcb, the traces on these look super cool.




For a slightly newer board, these are triple-shot ABS and are the ones most people know about. Unfortunately the modifier keys on these aren't compatible with any modern topre board so you would have to mismatch caps if you want to use these with a stock board. A custom topre board with these would be pretty cool to see, but I am not aware of any customs, which is a shame since these are such good caps.


It is a shame that no one makes such gigantic enter keys anymore.


And a later typewriter module, this one has PBT double dye-sub caps for most of the caps, but the enter key is pad printed and the space bar is ABS. The molding on these caps isn't as good as the others. They are thinner and there is slight flashing, still PBT is pretty nice and the double dye-sub is nothing to shake a stick at.




A topre compatible BAE and its pad printed


This one is a membrane based mechanism, and I'm posting the back of this to illustrate how easy it is to not use shitty rivets to hold things together. Even clips are preferable. This thing is so much easier to open and clean than an M.


The domes are attached directly to the membrane, and the membrane has what appears to be jumpers. I have never seen jumpers on a membrane before, so this is pretty interesting.




A better look at the jumpers.

[zrrion]

And an overview of the keycaps/sliders that I have come across:


From left to right we have a Brother 9300 from '82, a Brother CE-something, and finally, a Brother EM-430.



As you can see, the oldest slider is also the tallest and the biggest around. The smoothness lessens the newer the slider is, the EM slider is the least smooth of the bunch, while the 9300 is very smooth, and the CE is closer to the 9300 but quite as smooth.


The hole for the stem is off-center for the oldest slider but for the other two it is centered. The hole at the top of the slider is also tapered a little to make cap insertion easier.




The two doubleshot caps side by side as well as some windowed caps. Note that the high profile caps do not appear to be the same profile as the modern high profile topre caps.



Comparing the profiles. I was not able to put the bottom row caps side by side for comparison so you will have to use your imagination.



And here we get to the good stuff. The 9300 aren't the same profile as the current topre high profile caps, but they are remarkably close the high profile sculpted spherical caps from SKCC switches. I would not be surprised if the caps were intentional copies.
Initially I picked up my 9300 thinking it was an undocumented SKCC typewriter because the caps looked like dead ringers for SKCC, and since it was so early (82) I though Brother might have used SKCC when the started making daisy wheel typewriters and then switched at a later point, but it looks like Brother (or whoever OEMed these) started with domes from the very beginning.



The stems on the Brother caps extend below the bottom of the cap and make comparing them side by side a little difficult, but when you set the switches on their tops, the difference in top angle becomes apparent. Differing mold markings between them and SKCC caps is to be expected, as the tooling would have to be different to accommodate the different stem, but when stood upside down it becomes clear that they have a slightly different angle, which would indicate pretty soundly that they were not made with the same tooling at all. No idea who made these caps, but I very much like them and discovering these caps is what prompted me to start this thread in the first place.

[zrrion]

If anyone has any additional variations of keycap, sensing method, or slider please post them here, additionally, if there are any non-typewriter/non-word processor keyboards that use proto-topre please post that here as well. I want to get as much info as possible on this so that I can make a wiki page for it.

[HC514]

Assuming you're only talking about the Brother design, there's already a page for the capacitive version here.

I submitted that one image on the page. Come to think of it, if that typewriter with the similar caps that you have isn't the capacitive version, that one could be a different version too.

[zrrion]

I only have contact based versions myself, but I recently ordered a version that looked a lot like the picture on the wiki so maybe I'll have a capacitive version to here before too long. I also ordered another brother typewriter with these caps that appears to have a metal switch plate instead of a single barrel assembly, and there might be more switch variation to document there.

I'm glad we already have a page for proto-topre though, it is easier to expand on existing pages. Would be nice to get wiki pages for the boards mentioned on that page, but I don't own any myself so I am not able to do that.

[zrrion]

okay, so I finally got ahold of a capacative version and they absolutely blow the conductive ones out of the water! It appears to be from a similar vintage to the two 9300s that I have, but it has a metal switchplate and the design of the switch is such that it doesn't hit the mat before bottom out making it feels way more solid. It feels more like a nice mechanical switch instead of a nice dome switch. If modern topre is similar to this I can maybe understand what this "good feeling of oneness with cup rubber" is all about. Like the 9300 this one has shrink tube on the ends of the stabilizer to reduce noise, but it lacks felt to silence it. I suspect that the felt is never present on designs that have discrete switches.



the sliders on these are different from the 9300, but they still have off center holes for whatever reason. The caps on this are white on black as well, as opposed to the white on dark brown of the 9300. I can't tell form the page on the wiki but I wonder if the 8200 has black or brown caps. Anyway, the caps on this board are the same sculpt as the 9300 but this is a 14.75u board instead of a 14.5u board, so the right side mods are not exactly interchangeable. It is super close in a lot of ways to an XT layout but I personally prefer the 14.5u layout of the 9300.





A nice shot of the domes and the PCB. There are extra holes in the plate that I assume was to allow the same plate for several boards. No idea if any other layouts/models were produced, or even what this one is. The seller did not have much info on it, and they were nice enough to remove the module (typewriter was dead anyway) so I did not get a chance to inspect the full thing for any info.


And for something super cool, a new switch type:










It is a Latching Brother foam & foil switch with an integrated LED. I doubt there is a non-latching version of this since Brother could use the dome&foam for any momentary applications. The switch has a completely different mount, and is used as the power switch for this typewriter. There are some jumpers on the PCB itself that the a pair of copper leaves make contact with to power the LED. This is a super convenient way to do this as it does not require any desoldering to remove the PCB. from the switchplate. The small layer of thin hard foam has lasted way better than any foam I have seen from this era, and I wish more f&f boards had used a design like this, it is really quite nice for a latching switch.





And a tear down of the switch. The external coil spring is not present on all switches, but is present on a few of the switches responsible for carriage movement that one would want to avoid accidentally pressing. These springs are also present on the rod stabilizers of longer switches, on the backspace, and on the spacebar.

[zrrion]

viewtopic.php?f=2&t=10405&p=421232#p421232
not a lot of content, but when looking up the xerox memory writer I found this post about it and it would appear that it uses the same sort of switches, but with different stems

[kelvinhall05]

Came across a Brother AX-24 with conductive domes. Feel pretty good, and the keycaps are just kick-ass. Pretty thick ABS double or tripleshots. Any questions about it?

[zrrion]

If it significantly varies from anything here then pictures would be great. Even if it doesn't, pictures are always cool. Typewriters don't get enough documentation imo

[kelvinhall05]

Hey man, sorry for the late reply. Here's an album with some pics of it:
https://photos.app.goo.gl/bv8QhxnbC1HjXtuX6
They feel ridiculously good...so good I'm going to attempt to convert it to USB. Should just be as simple as treating it as if it was a hand-wired matrix/board, right?

[zrrion]

Yeah, you should be able to wire the ribbon cable up like a normal matrix. They are very nice domes so it should be great to type on.

[zrrion]

Confirmation that the caps posted in this thread are all compatible with modern topre. Modern topre is not compatible with the proto topre slider but I doubt anyone really wanted to do that anyway.

Edit: Modern topre uses a different slider for stabilized switches that is not compatible with proto-topre at all. This really isn't an issue since most if not all proto-topre appear to use a different form of stabilization. Generally rod stabilization, but newer examples have used an alps-like wire stabilizer. At either rate it is something to keep in mind.

[guidemetothelight]

hey man , first of all , great project ! those switches / caps are waaay better then people would give them credit for.
Could you maybe tell me what typewriter models correspond to which picture , so i can add them to my compendium ?
I already got the Brother EM-420 out of your pics but the other ones do not have names written on them.

Best Regards
Nick