Along with a good friend of mine I've been speaking with Alastair at ZX ZIGG the past few months about making an internal 16k SRAM module available for the ZX81. I wasn't keen on cutting tracks on the boards to install 16k internally with the methods that I'd read others performing so I spoke with Alastair and he put together a design for a new module and built a working prototype earlier in the year with which professionally produced boards have now been manufactured. The boards were designed specifically for issue 1 boards so there is a little more manual work to install them on issue 3 boards with wire jumpers used in place of one row of pins. See the image attached of the module installed on both the issue 1 and issue 3 board. I assume they will be available to purchase from him any time now, I bought ten several weeks ago but haven't yet had the time to begin installing any.
issue1 and issue3 SRAM module.png (1.01 MiB) Viewed 3807 times
Is there a version for the boards with the single 0.6" socket for the RAM? None of my zeddies have 2 sockets. Or any sockets for that matter. All my chips are soldered in. I suppose if I'm desoldering the RAM chip anyway then it wouldn't be that much more hassle to empty out the filled-in pads.
sirmorris wrote: ↑Sat Jul 01, 2017 8:12 amIs there a version for the boards with the single 0.6" socket for the RAM? None of my zeddies have 2 sockets. Or any sockets for that matter. All my chips are soldered in. I suppose if I'm desoldering the RAM chip anyway then it wouldn't be that much more hassle to empty out the filled-in pads.
You can request not to have the pins fitted to the right hand half of the module for the issue 3 boards which require a few jumper wires instead. The module can be soldered directly to issue 1 boards or in standard 18 pin DIL sockets.
I like the fact that to remove the upgrade only a few wires would need to be desoldered and the module unplugged from the sockets to revert the board back to standard chips without any damage
Lardo Boffin wrote: ↑Sat Jul 01, 2017 10:26 amThat looks rather good. Any idea of price at this stage?
Alastair mentioned roughly the same cost as the Spectrum lower RAM module or slightly less.
I suppose if I'm desoldering the RAM chip anyway then it wouldn't be that much more hassle to empty out the filled-in pads.