Need help reverse engineering Timex Store Demonstrator ROM file

Discussions about Sinclair ZX80 and ZX81 Hardware
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XavSnap
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by XavSnap »

Fore copper view:
store1.jpg
Mirrored back view: (user view from the rear side)
store2.jpg
store4.JPG
store3.jpg
HQ:
store3.jpg.zip
(251.08 KiB) Downloaded 67 times
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dessony
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by dessony »

With the case installed, you would have to use an extension cable. If the computer is uncased, then full room for 27C64 or 28C64 to make some EPROM/EEPROM modifications.

The board could use more than 2.5 centimeters of height raise to ensure a 7805, a 74LS244, an electrolyte capacitor, and a "loaded" 28 pins socket not hitting against the back of the case. But not the edge connector. And the edge connector's holes should be a little bit larger to ease the new connector onto the new board before the soldering job, not struggling to push into the board.

I plan to use 28 pins machine-tooled socket to go with Aries' 28 pins low-profile ZIF socket.

XavSnap, do not make a new board version yet. :!:

Cheers,
DesSony
Attachments
Front side with ICs
Front side with ICs
Front side No IC
Front side No IC
Cased & ZIF  no space!
Cased & ZIF no space!
Back side
Back side
Aries Tall Socket Front side
Aries Tall Socket Front side
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Paul
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by Paul »

How about moving the EPROM up?
Maybe swap line 1 and 2 of the Chips?
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mrtinb
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by mrtinb »

Looks like the problem I had on my first PCB. Chips on the front side is only possible, if they are not socketed.
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ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
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Paul
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by Paul »

We can also solder the PCB-Connector on instead of in the Holes of the PCB which gives us some milimeters
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dessony
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by dessony »

Paul and Mrtinb,

I am not a board designer. XavSnap is. I wanted the board bit a little taller around 2.5 centimeters or more.

Cheers,
DesSony
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Paul
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by Paul »

XavSnap wrote: Mon Oct 03, 2022 9:47 am
Hi Xavier, would you modify the board for us or give the sources to me that I can modify it to our Ideas?
In theory, there is no difference between theory and practice. But, in practice, there is.
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XavSnap
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by XavSnap »

Hi Paul,

All sources are free to a personal use, and are available on my forum :
viewtopic.php?p=46119#p46119
(Not VPN friendly forum!)

The main board can be used with a vertical or a angled horizontal connector, but if you had to use it in a horizontal release, you won't be able to put a new card on it.

(c) AliExpress picture.
angledconnector.JPG
The simply way to get extra space between the ZX81 and the card, is to put a ZXprinter/Alfacom printer connector!
...or use a wrapping connector to increase this space.

(c) AliExpress picture.
angledconnector2.JPG
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Paul
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by Paul »

Great, thank you.
It works great for me, no VPN ;)
In theory, there is no difference between theory and practice. But, in practice, there is.
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Paul
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Re: Need help reverse engineering Timex Store Demonstrator ROM file

Post by Paul »

In the KiCad Version I downloaded the 74LS133 has VCC and GND swapped,
please check if GND is on Pin8 and VCC is on Pin16.
In theory, there is no difference between theory and practice. But, in practice, there is.
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