Need help reverse engineering Timex Store Demonstrator ROM file

[XavSnap]

Fore copper view:

Mirrored back view: (user view from the rear side)

HQ:

store3.jpg.zip

(251.08 KiB) Downloaded 253 times

[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

[Paul]

How about moving the EPROM up?
Maybe swap line 1 and 2 of the Chips?

[mrtinb]

Looks like the problem I had on my first PCB. Chips on the front side is only possible, if they are not socketed.

[Paul]

We can also solder the PCB-Connector on instead of in the Holes of the PCB which gives us some milimeters

[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

[Paul]

Hi Xavier, would you modify the board for us or give the sources to me that I can modify it to our Ideas?

[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.

[Paul]

Great, thank you.
It works great for me, no VPN

[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.