Sinclair ZX80 / ZX81 / Z88 Forums

That's correct, we had a local channel 2 so we always used 3 for computers... but this ZX81 is rather rare in that it has a 3/4 selector instead of the normal 2/3 selector. In fact, it's the only one I've personally ever seen. All TS1000 machines were 2/3. It's a very first generation US model... an...

As a side note... the Issue 1 US board on my ZX81 has a different RF Modulator... in fact, it has a Channel 3 and 4 selector switch on it instead of the standard 2 and 3. (Mine is dated a few weeks earlier as well, being the 28 week of '81.) See here: IMG_20171104_112639.jpg IMG_20171104_112559.jpg ...

I have a model for the 3K ram pack, but I haven't printed them out yet. I plan on making complete sets at some point. I'm going to reprint the current molds after I correct a few minor issues. The lower mold needs to be printed vertically to avoid it collapsing and the upper mold needs to be inverte...

The clone board isn't perfectly square... the real board drops in perfectly. As for the smoothness, yes, I'm printing a new set at a higher resolution and will be able to make it very smooth. This was literally the very first test of the new vacuum forming machine at our local makerspace... so lots ...

Just did the first test pull of my molds. They worked almost perfectly. There are a couple minor flaws, but the molds and the technique are perfect. I need to resize a couple things based on the thickness of the material used, but that's simple enough to scale it. Here are a few pictures of the proc...

In case anyone is interested, here are my injection molds for the ZX80. I'm planning on testing them this week, so consider them still a work in progress, but they're close. I need to make sure there is enough air passthrough to allow the vacuum to pull all the way down into the deep pockets. I am u...