a mother board is available the ZX81 (GBO8J) and will accept the Sinclair 16k RAM pack and up to three plug-in modules. You will need four PC edge connectors 2 x 23 way (RK35Q) and the pcb
page 47
GBO8J ZX81 Extendiboard Price £3.95
RK35Q P.C. Edgecon 2 x 23 way Price £2.25
Yes, it’s a shame that Maplin (the original company) went into administration and closed. A new company bought the brand name and opened up as an on-line shop. But they don’t sell kits or indeed electric components.
I spent many an hour browsing through the Maplin catalog (that was available in WH Smith’s, a high street newsagents and book store). Then later, in their shops (they opened one in Bristol, eventually they had three in the Bristol area) and on their web site.
Was a big part of my life in my early 20's at college, even bought a couple of the cover art posters. Wish I still had them, but they did not survive the repeated moves from one digs to another
The Mapin shop in Nottingham was good but parking was a nightmare. The later shop that opened in Mansfield was great, but by then the electronic components were pushed to a little store room at the back. Their Ni-Cad batteries were the bargain of the century though. Still have a few left.
Last edited by redgatemodels on Sat Nov 30, 2024 2:57 pm, edited 1 time in total.
I have one of those little extender boards somewhere. As for Maplins, whilst they were convenient they were a bit pricey.
I used to go to a Mondo Maplin which meant they should have at least one of everything in the catalogue but it was never the case.
I do remember getting a nice trio of American Eminence speakers for the stage amps I was building for myself and being able to buy components in small quantities was useful I found.
Like Redgatemodels experience, the Maplin store I used ended up with an ever decreasing components stock and became a glorified version of Toys are us where it was easier to buy a remote controlled helicopter than a bag of resistors.
In the end I used Farnell whose HQ was just up the road, had a thousand of everything plus it had a trade counter now sadly defunct with mail order being the current way of purchasing things.
I saw a reference to this board, but not much detailed information on it. Now I'm understanding how y'all used this part, like this photo from Mark with I/O cards
1024MAK wrote: ↑Tue Aug 01, 2017 9:53 am
I also have the Maplin extension board. That's what my GA90X plugs into (it having a "male card edge" rather than it's own female socket).
Maybe a picture will demonstrate what I mean more clearly...
And thanks to siggi. "backplane" was the term I was trying to think of. Maplin called it a "motherboard" in the magazine, but backplane is more descriptive of its function
siggi wrote: ↑Mon Aug 07, 2017 10:09 am
Torsten made a new backplane similar to the Maplin board
With all this hardware, it's as if the ZX81 could run a nuclear power station!
Just saw this old project from kmurta using what looks like an Extendiboard. Is that a flexible board-to-ZX81 connector? I would think using a ribbon cable might eliminate connector wobble issues
Since none of these boards are available any longer, what is the current go-to for a hobbyist slot extender board?
David G wrote: ↑Thu Dec 12, 2024 11:07 pm
Since none of these boards are available any longer, what is the current go-to for a hobbyist slot extender board?
Standby alert 
