Different keyboards on Model 4Ds?

[Blendama]

Good afternoon!

After gifting my Model III to my sister's family in 1984, and then regretting that decision every waking moment of my life, I made the decision a couple of years ago to get back into TRS-80s...and figured Is should do so with a 4D. I kept my eyes open for one in decent shape; I found one online last year and picked it up. Last week, however, I found one, in the original box, with all the original packaging at a neighbour's garage sale. How could I say no? On top of that, it had had never been opened, so I get to break the warranty seal when I recap the power supply.

The one I purchased last week has a low serial number (approx. 1,000) while my other 4D has a serial number in the high 8,000s. They're now sitting side-by-side and when I was comparing the two, I noticed something; the keyboards have very different feels to them.

The low serial numbered unit has a clickier keyboard and an absolutely quiet reset button. The space bar is also quite loud when I bottom out on it.

The higher serial numbered unit has mushier, quieter keys and the reset button makes that loud click you expect.

The reality is that I can't tell which one I prefer. Except for the space bar, I think I prefer the clickier keyboard, but that space bar could be a deal breaker!

(I should say that I also have a 4P and I absolutely LOVE that keyboard...Id say that's the best one that Tandy ever used!)

So did Tandy source different keyboard manufacturers for the 4 & 4D? If so, how do these compare to, say Model 4/III keyboards? I know that some were made by Alps, but I'm not sure if these ones are.

Thinking about it, Tandy saw this as the last 8-bit computer, and probably wanted to reduce costs as time went on; so I assume that the keyboard on the high serial numbered unit is probably cheaper than the other?

I only have these 2 machines to compare to, so I thought I'd ask the experts!!

Thanks!

 

[TRS-Ian]

Yes the 4D did come with two types of keyboards, the early one is the flat membrane type, basically the same as on the previous Model 4 (Gate Array) microcomputer, with an extra key (Backspace). It's a sealed unit and doesn't lend itself to easy repair if a key fails. That said others have successfully repaired them and they are not that bad to type on though in my opinion, inferior to the ALPS keyboard.

Later on they changed to an ALPS keyboard, without warning, and with no reason given, which has the traditional 4-lug key switches and these are easily repaired by unsoldering individual key switches and cleaning/replacing them. To me it feels better to type on than the membrane type, but that is just my opinion.

Hope this helps.

Ian.

 

[pski]

What's an easy way to tell which keyboard I have in my 4D without opening the machine?

 

[TRS-Ian]

Reset button feels lifeless on a membrane keyboard but has a definite click on an ALPS.

Shape of the keys is slightly different but only a trained eye can pick it up.

Or just post a high resolution photo of the right side of the keyboard and I'll be able to tell you.

Cheers,

Ian.

 

[pski]

Reset button feels lifeless on a membrane keyboard but has a definite click on an ALPS.

Shape of the keys is slightly different but only a trained eye can pick it up.

Or just post a high resolution photo of the right side of the keyboard and I'll be able to tell you.

Cheers,

Ian.

I think its a membrane keyboard. Reset button feels weak compared to my Model III.

 

[Blendama]

Pete, I'm curious; what's the serial number of your 4D?

Mine with the membrane keyboard is 001021

 

[pski]

Pete, I'm curious; what's the serial number of your 4D?

Mine with the membrane keyboard is 001021

005121

 

[Blendama]

So in other words I was 100% wrong in my assumption!

if they went from membrane to ALPS then the actually improved the keyboard quality as production went on...

If I couldn't tell the difference then I'm guessing that all those years of using those crummy $20 Lenovo membrane keyboards at work have had an impact on me!!!

I notice that the "newer (a.k.a. higher serial numbered) 4D requires slightly more force than the "older" keyboard, so I'm guessing that the newer one is indeed the ALPS while the older one is membrane. I've attached pics; Ian, I'd be interested in your thoughts. The only differences I can tell when I view the pics is a slight difference in the font on some keys (such as BREAK, BACK SPACE, CLEAR).

The 128K is the "newer" 4D. Ian, since these are gate array machines, what do I need to do to move the 64K over to the other machine? Once I move the chips, are there any jumpers, etc. I need to adjust? I'd also like to do a full test of both machines, but I have no utilities...what would you recommend?

Thanks!

 

[Blendama]

Well my newer machine is serial number 008748 so it looks like the move to ALPS occurred sometime between yours and mine...

BTW, any idea how many 4Ds were made? What's the highest serial number anyone has come across?

 

[Blendama]

Actually now that I look at the pictures again I see there's a difference in the bezels. If you look right under the bottom row of keys, the suspected ALPS bezel simply has a "bump" but the suspected membrane bezel has an extra little lip...I know I'm not explaining it well but take a look at the pics and you'll see what I mean....

 

[TRS-Ian]

Pete your 4D has the membrane keyboard, and Blendama your 64K machine has the membrane and 128K has the ALPS.

The vague way I can describe it is the curved edges of the top of each keycap are more rounder on the ALPS than the membrane. I know that's a terrible description but its the best I can come up with at the moment.

Re. 128K upgrade, generally with such old computers if they are working well we don't tempt fate transferring parts from one to the other. In your case I would buy 8 64Kx1 but Motorola 0665 Ram chips and upgrade the 64K system yourself. Notejump manual explains which jumper to move or wire to unsolder and move.

Hope this helps,

Ian.

 

[vwestlife]

My Model 4D is serial number 491 and has the membrane keyboard. The keys are completely linear (no tactile "click" or bump in the travel; the downstroke has the same force as the upstroke) and are light but springy-feeling. The keys are much softer and quieter than the Model I keyboard.

 

[Blendama]

VWestlife, I watched your YouTube videos on your 4D...and what struck me was that you reset button made no noise when clicked, just like my s/n 1021 computer...so that's what lead me to believe that mine wasn't a one-off and they most likely changed keyboard manufacturers part-way through the manufacturing process.

BTW, love your videos! You should open up your garage to public viewings! I could spend all day in there!

 

[Trash-Eighty]

Pete your 4D has the membrane keyboard, and Blendama your 64K machine has the membrane and 128K has the ALPS.

The vague way I can describe it is the curved edges of the top of each keycap are more rounder on the ALPS than the membrane. I know that's a terrible description but its the best I can come up with at the moment.

After some time brooding over the photos I have found other differences.
My result: another distinction could be the slight different typesetting of some letters on the keyboard's keys.

Among other barey visible differences the middle bars of the letters E and F have different lengths.

On the mebrane keyboard the E and F have a wide bar.
On the ALPS keyboard the E and F have a narrow bar.

I have attached photos with the differences highlighted.

-Rainer

 

[Blendama]

Wow, nice work!