So, it would seem that I accidentally took about a semester long break from Cemetech, but let me tell you, I've started a lot of new projects, and this is one of them.

A long time ago, I posted in this topic on Cemetech. Welp, that chip is still kicking around, and I've been able to talk to it and actually use it. But, without a RAM chip to go along with it, all I could do was execute single line commands instead of actually using it like a BASIC computer, doing things like
Code:
10 print "hello, Cemetech"
20 goto 10
run
I have located the RAM chip that was built specifically for this MCU, the Z6132. I found one on Ebay and snatched it up for about $7. It will likely come on the 24th.

Since then I have built the architecture outlined in this datasheet for the Z8671 "Seven Chip Computer" except I'm not including a ROM chip, and all the communication is handled by an ATMEGA which will also handle a keyboard matrix and TFT LCD screen to create a 6-chip Pocket BASIC Computer.

Here's what I've built so far:


I'll update this as major milestones occur. Let me know what you think! Smile
Very compact design - cant wait to see more!

I would love to build something like this one day.
Made some strides while putting off finals prep Very Happy

I 3D printed the bottom case for this thing that will house the logic board, keyboard, battery and charger. The logic board is underneath the keyboard, screwed together with standoffs in each corner. The battery charger is underneath the battery, but I'm holding another one just to show what it is. The top of the case has a hole for USB charging, and the side of the case (you can almost see it in the picture) has a hole for an FTDI friend. This'll be for programming the ATMEGA without having to remove it.

I'm working on printing a keyboard overlay so I'll actually be able to use the keyboard. I'm planning on putting letters on the keys by using a technique similar to that outlined in this video. I'll probably do something similar for the front case.

Enough talk, here's a picture!

The Z6132 RAM chip came way earlier than expected! I wired it up to the data bus according to the application note, and to my amazement it worked perfectly! Surprising for a chip of that age bought on eBay.
I've also gotten the ATMEGA talking to the Z8671 at 9600 baud through software serial, so that I can use the hardware serial to program the ATMEGA without worrying about the Z8671 interfering with it.
Now that this is all working, the things I have left to do are to wire up the keyboard matrix, the screen, finish the program for the ATMEGA, and finalize the case which will need a little more work to accommodate room for wires (I had already done this, but they ended up taking up more space than I thought they would)

Here's a picture of the finalized logic board!

Very cool - any chance of seeing the other side of the board?
tr1p1ea wrote:
Very cool - any chance of seeing the other side of the board?

Sure thing! A rough color code for the wires:
Red: +5V
Black: Ground
Blue: Data Bus
Green: Serial Communication
Orange: Misc. Signals

Also, don't be alarmed, that battery is only 1500 mAh, not 15000 like it says. Not sure how that happened...

Click to enlarge (goes for all the pictures in this thread)
Major, major update:
I have finished the keyboard matrix, soldered it in to the logic board, and created a new front plate that accommodates the new keys. This means all hardware aspects of this project are essentially done. The only couple hardware things left to do are to make a mechanical solution to hold in the screen protecting acrylic, find some 2/56 heat set inserts for the top two body screws, and get some tiny letters and symbols cut from vinyl somewhere for labeling the keys.

I started doing a little programming this morning and I got the keyboard working exactly how a qwerty keyboard should (except for the shift key, right now it behaves like CAPS) and the only things I see left to do with programming are to implement a screen scrolling routine when the text goes off the bottom, and figure out whatever ascii code the up arrow is in the Z8671 app notes linked above. I thought it was 24, cancel, since it does print out an up arrow when I send it to the computer, but when I use that and type exact lines of code from the app note, if gives me a syntax error. Anyone who could have some insight with that, please do let me know.

Anyway, here are some nice pictures of what is almost the finished state (ignore the missing screws Razz ) :
CLICK TO ENLARGE

A couple minutes with Illustrator, a trip to the campus print shop, and an hour and a half with some micro tweezers later:

Neat! Are those little vinyl decals?

The bubbles on the screen look annoying- is that a "some peeling required" situation?
Looks pretty awesome! Very Happy

Although that switch needs a nice cover too Razz
They are tiny vinyl decals! I just finished brushing Mod Podge over all of them so they won't peel off during use.

And yes, still gotta peel off that screen plastic protector, but I'm going to do that after I get the screen protecting acrylic mounted in the front case. Good catch!

EDIT: @mateo, unfortunately that switch won't be getting a cover Sad I could probably turn it black though so it blends in more.
Cool, keep up the work! Smile
No idea why this is here but...
This looks amazing dude. It looks great!
Wow, that's fantastic!! I love the letter decals and wish I had used some for my wooden TI-82 project.
Thanks for the support, guys Smile

I realized I never made a concluding post here since it is now totally done. I figured I'll just leave some pretty eye candy and call it good.

  
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