Other The 'Random Crap I'm Too Nostalgic To Throw Away' Thread

Let's have another one from the collection:



Hewlett Packard 200LX Palmtop PC. Two whole megabytes of RAM, MS-DOS plus HP's own GUI on top, and a full-size PCMCIA slot which on this one has a 5MB SSD in it. Bunch of the usual utilities, plus Pocket Quicken and Lotus 1-2-3.

The display has no backlight and only does four shades of grey, but it emulates CGA in two modes: squished and zoomed. There's even a surprisingly loud PC speaker in there. The whole thing runs off two AA batteries.

Man, I miss palmtops.

 

Might make this a regular thing, I'm enjoying digging out some of my collection...



A Sinclair ZX81, built by my own fair hand from a NOS kit. Actually, there's a gallery of the build process over on Imgur.

Upgraded with a heatsink on the ULA and a composite video output in place of the no-latch RF signal that doesn't play well with anything other than vintage black an white TVs. The thing on the rear is a ZXpand module, which adds 32kB of RAM to the 1kB internal, provides save and load functionality from an RSMMC card, upgrades the BASIC, and offers a high-resolution mode. Where "high" is, like, 320x240.

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I also took the guts out of the factory linear PSU, which was a useless US 120V one anyway, and fitted a modern switch-mode 7V supply in the housing. Weighs nothing, keeps the ZX81 nice and cool. There's a ZX-AY somewhere, too, which adds a joystick port and a Yamaha AY synthesis chip for proper music - fits to the ZXpand, but then the ZXpand doesn't fit in the lovely metal case any more.

Not the rarest of the ZX81s I've ever owned, though. That'd be a first-production-run model with 'cockroach' mod:

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Basically, there was a bug in the ROM's division code, but the thing was already late getting out of the door and Uncle Clive was a scrooge so rather than burn new ROMs - remember, these were proper ROMs, not EPROMS, so once written they couldn't be modified or overwritten - he got the factory to fit a bit of protoboard with some logic gates over the top, fixing the bug by changing the addressing mode of a single instruction and fixing the flaw.

I don't have that one any more, sadly - it's one of the many, many devices that found a new home in the office move to make room for my youngest.

EDIT:
Oh, I forgot my favourite thing about the ZX81 and its predecessor the ZX80, and it also ties in to Uncle Clive's miserly attitude. You know how volume discounts work, right? The more you buy of a part, the cheaper the part is. So if you add one of something to your design, it's more expensive per-part than if you add two or three.

Which is why the ZX80/ZX81 use 3.5mm TRS jacks for everything. Two of those, EAR and MIC, make sense: one's audio in and the other's audio out, allowing you to connect a tape deck to save and load your software. The other... not so much. It's the 9V power input. And all three are right next to each other on the same side.

Yes, that does mean that you might accidentally plug the 9V power supply into the audio circuitry. No, the machine does not like it when you do that.

 

You have no idea. Although the collection is a lot smaller than it used to be, thanks to two big clearouts.