ZX81XRAM - external 32k memory module +HRG

[PokeMon]

Well a new module as external 32k memory extension with HRG support is provided at http://www.sellmyretro.com.
There are 3 versions:

complete module
http://www.sellmyretro.com/offer/details/2705

IMG_5975k.JPG (181.13 KiB) Viewed 3070 times

kit with all components (unsoldered)
http://www.sellmyretro.com/offer/details/2703

IMG_5971k.jpg (106.57 KiB) Viewed 3070 times

board only
http://www.sellmyretro.com/offer/details/2704

IMG_5943k.JPG (198.58 KiB) Viewed 3070 times

More technical details can be found here:
viewtopic.php?f=6&t=1129

[PokeMon]

The ZX81XRAM is available again and optional mounted in a case with additional reset button and in two versions (with simple and "through" connector):

Version with "simple" connector like the square Sinclair 16k memory modules:

IMG_6124k.JPG (109.73 KiB) Viewed 3019 times

IMG_6125k.JPG (96.6 KiB) Viewed 3019 times

IMG_6123k.JPG (118.87 KiB) Viewed 3019 times

[PokeMon]

Second version with "through connector" for adding other modules/items using the expansion bus of Sinclair:

IMG_6129k.JPG (69.12 KiB) Viewed 3019 times

IMG_6128kk.jpg (103.52 KiB) Viewed 3019 times

IMG_6130k.JPG (116.11 KiB) Viewed 3019 times

[PokeMon]

One important advise for all people using the assembly kit version and solder the parts self:

The connector should be placed with a distance of minimum 5mm like Sinclair did or at least as far from the board as possible due to length of the contacts.
Please see pictures below. Every mm counts. Otherwise the module can not be connected very good to the original Sinclair because the connector is a little bit inside of the Sinclair case and the back is a bit "curvely" created, forcing the connector to go deeper into the case.

IMG_6116k.jpg (114.32 KiB) Viewed 3019 times

IMG_6118k.JPG (89.86 KiB) Viewed 3019 times

[PokeMon]

Last but not least:

The ZX81XRAM module has been tested with the ZX80 as well and can be used with one restriction without modifications:
The ZX80 supports only 16k of RAM, in address range $4000-$7FFF.
The RAM is also enabled during refresh phase and so called "HRG compatible".

You can find all items here:
http://www.sellmyretro.com/user/profile/PokeMon