Ace nearly up and running

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anightin
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Ace nearly up and running

Post by anightin » Sat Aug 08, 2020 6:28 pm

Built a Jupiter Ace when listening to Abug last and have something on screen at least.


First two bugs were my poor choice of transistors, one on the composite video board and one amplifying the signal into the CPU. Once those were fixed the the CPU is now getting a good clock and it seems to be coming out of reset and it's outputting a PAL composite video image, and there seems to be ROM character data scrolling through video memory and at least.


Now to work out why it's not quite getting up and running correctly ...
IMG_7533.jpeg

If anyone has suggestions of what to check next I'd appreciate it. :D

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anightin
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Re: Ace nearly up and running -- now Alive!

Post by anightin » Sun Aug 09, 2020 6:02 pm

Ace is now working!

There were 4 simple faults and one was down to me. I had missed soldering pin 14 of one of the video RAM chips -- the one that deals with the high 4 bits of video memory. I guess the floating pin was causing the display circuit to output garbage as per my previous post. The other issues were PCB layout errors in that 3 keys had extra traces present that would have caused some confusion too no doubt.

Looks like someone else had already spotted the keyboard matrix issue so we must have the same repro boards :)

https://youtu.be/PDVVFrXwiAQ

IMG_7547.jpeg
Screenshot 2020-08-09 at 17.44.44.png
IMG_7548.jpeg
Now to build a proper keyboard and housing for it -- looking up the key matrix position and shorting contacts is very tedious :)

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richardtoohey
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Re: Ace nearly up and running

Post by richardtoohey » Mon Aug 10, 2020 1:04 am

Looking good =D>

I've always been curious about the Ace - the choice of Forth was a "brave" one.

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Re: Ace nearly up and running

Post by anightin » Tue Aug 18, 2020 9:03 am

Quick update in that the keyboard is up and running. I need to do a couple of tweaks to to the layout but pleased with the initial results :)
IMG_7600.jpeg
IMG_7599.jpeg

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anightin
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Re: Ace nearly up and running

Post by anightin » Tue Aug 25, 2020 3:25 pm

Keyboard project nearly complete. New tweaks worked a treat and I now have the bottom row of keys in the right places :lol:
IMG_7631.jpeg
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IMG_7636.jpeg
IMG_7637.jpeg
Just need to fit the keyboard and Ace into the donor case now...
7638.jpeg
7639.jpeg

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Re: Ace nearly up and running

Post by richardtoohey » Thu Sep 03, 2020 12:52 am

Keyboard looks great.

Was that an add-on BITD? I remember there were add-on keyboards for the ZX81, so was this something similar for the Ace?

Or just something you've done yourself? Just curious! :D

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anightin
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Re: Ace nearly up and running

Post by anightin » Thu Sep 03, 2020 8:16 am

The case is an old DK’Tronics ZX81 one I recently acquired.

http://www.retrogamescollector.com/earl ... ktronics2/


This was the inspiration for the keyboard, as I still have the original ZX81 keyboard for the case but the wiring for the matrix is quite different.

Without wanting to hack the original keyboard or case I designed a new PCB that would fit the case.

There was an external keyboard add-on BITD for the Ace from Memotech, again originally for the ZX81 but reworked to fit the Ace

http://www.jupiter-ace.co.uk/hardware_m ... oard.html.


Here are some more snaps of the 'DK integration'.
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This is the old keyboard I have since moved to storage should I want to restore the case to its original state:
IMG_7552.jpeg

Next step is to build a bus extender to poke out the back of the case :)

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1024MAK
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Re: Ace nearly up and running

Post by 1024MAK » Thu Sep 03, 2020 11:48 am

Yeah, the black plywood base gave it away as a dk’tronics case :wink:

Later on, their ZX Spectrum cases had plastic bases.

Mark

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anightin
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Re: Ace nearly up and running

Post by anightin » Thu Sep 03, 2020 12:38 pm

1024MAK wrote:
Thu Sep 03, 2020 11:48 am
Yeah, the black plywood base gave it away as a dk’tronics case :wink:

Later on, their ZX Spectrum cases had plastic bases.

Mark
I'm a fan of the plywood one at least for this job as the material is so easy to work with and very light, and has a nice feel to it vs cold plastic.

:D

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Re: Ace nearly up and running

Post by richardtoohey » Fri Sep 04, 2020 3:43 am

Looks nice & solid! =D>

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