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geekhack Projects => Making Stuff Together! => Topic started by: jdcarpe on Fri, 09 March 2018, 10:42:49

Title: JD-99/4A Project
Post by: jdcarpe on Fri, 09 March 2018, 10:42:49: So, I had this CRAZY IDEA...

Let's re-create this computer that started it all for me...the Texas Instruments TI-99/4A

(https://i.imgur.com/zLil4dT.jpg)

If you open it up and get rid of the main board, you have a keyboard and a shell housing.

Now, the later versions of this computer used a very cool keyboard indeed. It was made by General Instrument, and used Alps SKCC switches. The stems were angled to give the uniform SA-profile (yes, they were made by Comptec) keys a nice slant. It has 48 keys, and uses an 8-unit spacebar. Well, the SA keys on the Alps keyboard version are beige, and don't match this black-and-aluminum housing at all. So let's get rid of that keyboard and start anew.

(https://i.imgur.com/rLOTVqp.png)

We can still use the switch mounting plate, since the holes are 14mm square. Just the thing for MX switches, right? Well, I hate handwiring, so I asked Talking Tree to help me with a PCB for it.

(https://i.imgur.com/8GP9zyZ.png)
Early render of the PCB. Final version will have other bottom row layout options.

There is no controller or other circuitry on the PCB. The row/column matrix is landed to pads on the top edge of the PCB, so that we can use ribbon cable to connect the matrix to a controller of our choosing (Teensy, Pro Micro, etc.).

Once we have the PCB made, I will install MX switches in the plate, and mount it back into the shell of the computer. Then, I will install a Raspberry Pi inside the computer housing to complete the build. I was thinking of using the cartridge slot on the right for expansion ports or an SD card reader.

It's nostalgic. It's insane. But it's kinda cool, no?

Anyone wanting to re-create this project could easily buy a non-working 99/4A on eBay cheaply. It might be harder to find the Alps keyboard, but one could always have a plate cut and mount it to the housing using standoffs.

Thoughts?

Big thanks to Talking Tree for the PCB help!!
Title: Re: JD-99/4A Project
Post by: jdcarpe on Fri, 09 March 2018, 10:44:20: (https://i.imgur.com/0vdkkbw.png)
Title: Re: JD-99/4A Project
Post by: ghostjuggernaut on Fri, 09 March 2018, 10:49:14: This has the potential to be very epic. AFAIK nobody has ever taken something like this and built an all in one system. Would be neat if this evolves into an AIO Linux box or something of the like. RPi can obviously do a lot, but what if we throw in a full motherboard with all the IOs needed for daily use.

Great work as always JD.
Title: Re: JD-99/4A Project
Post by: LightningXI on Fri, 09 March 2018, 10:50:46: This is really cool! I look forward to seeing progress to this project. I will be following closely...
Title: Re: JD-99/4A Project
Post by: noSatellite on Fri, 09 March 2018, 10:57:34: This is an awesome idea - some of my first computer memories are of playing frogger off a tape drive on a TI99/4A.

Quote from: ghostjuggernaut on Fri, 09 March 2018, 10:49:14
Would be neat if this evolves into an AIO Linux box or something of the like. RPi can obviously do a lot, but what if we throw in a full motherboard with all the IOs needed for daily use.

Great work as always JD.

Might be cool to have something like that dedicated to programming keyboards? Or is that overboard? Not sure...
Title: Re: JD-99/4A Project
Post by: jdcarpe on Fri, 09 March 2018, 10:57:50: Quote from: ghostjuggernaut on Fri, 09 March 2018, 10:49:14
This has the potential to be very epic. AFAIK nobody has ever taken something like this and built an all in one system. Would be neat if this evolves into an AIO Linux box or something of the like. RPi can obviously do a lot, but what if we throw in a full motherboard with all the IOs needed for daily use.

Great work as always JD.

That's a good idea, but I don't know if there is room even for a Mini-ITX mobo in there. It's pretty cramped:

(https://i.imgur.com/mJEc81Y.jpg)
Title: Re: JD-99/4A Project
Post by: TalkingTree on Fri, 09 March 2018, 10:59:07: Quote from: jdcarpe on Fri, 09 March 2018, 10:42:49
Big thanks to Talking Tree for the PCB help!!
My pleasure.

I'm following closely as well. This has got to be a great project.
Title: JD-99/4A Project
Post by: ghostjuggernaut on Fri, 09 March 2018, 11:11:57: Quote from: jdcarpe on Fri, 09 March 2018, 10:57:50
Quote from: ghostjuggernaut on Fri, 09 March 2018, 10:49:14
This has the potential to be very epic. AFAIK nobody has ever taken something like this and built an all in one system. Would be neat if this evolves into an AIO Linux box or something of the like. RPi can obviously do a lot, but what if we throw in a full motherboard with all the IOs needed for daily use.

Great work as always JD.

That's a good idea, but I don't know if there is room even for a Mini-ITX mobo in there. It's pretty cramped:

Show Image
(https://i.imgur.com/mJEc81Y.jpg)

I wasnt necessarily speaking on this specific project, more for a progression this could lead to.
Title: Re: JD-99/4A Project
Post by: jdcarpe on Fri, 09 March 2018, 11:14:58: Quote from: ghostjuggernaut on Fri, 09 March 2018, 11:11:57
Quote from: jdcarpe on Fri, 09 March 2018, 10:57:50
Quote from: ghostjuggernaut on Fri, 09 March 2018, 10:49:14
This has the potential to be very epic. AFAIK nobody has ever taken something like this and built an all in one system. Would be neat if this evolves into an AIO Linux box or something of the like. RPi can obviously do a lot, but what if we throw in a full motherboard with all the IOs needed for daily use.

Great work as always JD.

That's a good idea, but I don't know if there is room even for a Mini-ITX mobo in there. It's pretty cramped:

Show Image
(https://i.imgur.com/mJEc81Y.jpg)

I wasnt necessarily speaking on this specific project, more for a progression this could lead to.

Oh yeah, for sure. Could even have a nice wooden and glass enclosure or something...
Title: Re: JD-99/4A Project
Post by: xondat on Fri, 09 March 2018, 17:08:57: Looking forward to more progress ;D
Title: Re: JD-99/4A Project
Post by: spacewolf on Fri, 09 March 2018, 22:02:22: This is fantastic. It'd be cool to see a case for just the keyboard that mimics the style too.

But also, as far as it goes for building a computer in there. I haven't seen one of those, but comparing to the size of the keyboard. I've definitely seen some production builds that would fit in there. Just pull everything out. Dremel any walls. It'd be interesting to compare measurements to an mITX board. Doesn't have to be a gaming rig. And if you wanted it to be. Just use the new Ryzen G chips. Won't be a beast, but it'll still chug along.

Sent from my Robin using Tapatalk
Title: Re: JD-99/4A Project
Post by: tex_live_utility on Sat, 10 March 2018, 20:28:22: Replacement keyboard modules for these show up on Ebay pretty often.
Title: Re: JD-99/4A Project
Post by: jdcarpe on Sat, 10 March 2018, 21:26:36: Quote from: tex_live_utility on Sat, 10 March 2018, 20:28:22
Replacement keyboard modules for these show up on Ebay pretty often.

That's true. You just have to be careful not to buy the Stackpole or Mitsumi versions. The Alps version for the later beige '99 is what you want to look for. I'm not sure if TI used different part numbers for the different keyboard versions through the years.
Title: Re: JD-99/4A Project
Post by: Ruskie on Thu, 12 April 2018, 09:04:39: Should you decide to go through with this, I imagine you could get away with a PicoPSU, which go up to roughly 450W, as well as a Mini STX Motherboard. I would love to see this come to fruition!
Title: Re: JD-99/4A Project
Post by: TalkingTree on Thu, 12 April 2018, 10:39:11: Quote from: Ruskie on Thu, 12 April 2018, 09:04:39
a PicoPSU, which go up to roughly 450W
What PicoPSU can supply 450W? Honest question.
Title: Re: JD-99/4A Project
Post by: regack on Thu, 12 April 2018, 13:28:43: Probably not enough room for a Mini-ITX without really compromising everything, but a NUC would work, and would probably make more sense in this... case...

JD always has neat ideas.