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Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Mon Oct 03, 2022 9:47 am
by XavSnap
Fore copper view:
Mirrored back view: (user view from the rear side)
HQ:
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 6:42 am
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
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 6:51 am
by Paul
How about moving the EPROM up?
Maybe swap line 1 and 2 of the Chips?
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 6:56 am
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.
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 7:01 am
by Paul
We can also solder the PCB-Connector on instead of in the Holes of the PCB which gives us some milimeters
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 7:03 am
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
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 7:07 am
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?
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 9:06 am
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.
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.
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 10:31 am
by Paul
Great, thank you.
It works great for me, no VPN
Re: Need help reverse engineering Timex Store Demonstrator ROM file
Posted: Tue Oct 11, 2022 3:31 pm
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.