The LittleGP-30: A tiny recreation of a very big deal from the 1950s

Hardware
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He also produced an electronic functional model of the Enigma cipher machine.

This desktop-calculator sized unit is a re-implementation of the Librascope LGP-30, launched by Royal McBee in 1956. The modern version is based on a roughly $65 Numato Mimas development board. To this, Müller added a tiny LED display, where the original, ingeniously, had a built-in oscilloscope hidden behind a tiny screen with cutouts to reveal the contents of the registers.

Müller told The Register:

I am really happy that I will now be teaming up with CEDS — the small company Oscar Vermeulen has set up together with a friend to make and distribute his series of PiDP replicas — to make kits available.

The CEDS version of the LittleGP-30 will be a complete redesign, with a front panel closer to the real machine (full button layout and a nicer “oscilloscope” display), and its own FPGA board instead of the Numato Mimas “piggyback” board. It will still come as a kit, with only the SMD parts pre-populated and all through-hole components to be populated by the builder.

But to manage expectations: The new LittleGP-30 will only come out later this year. It’s actually number two in our joint pipeline – first will be my Enigma touch, which CEDS will also make available and which is pretty far along. And for the vintage computing enthusiasts, CEDS will release Oscar’s PiDP-1 soon. Exciting times, and I struggle to find time for my day job…

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A few links away, a couple of nice papers. First, from 1957 all about how the LGP-30 works, down to the logic equations:
The Logical Design of a Simple General Purpose Computer (10 pages, Stanley Frankel)

Second, a more recent perspective:
Programming Then and Now: From the LGP-30 to the Laptop (32 pages, Keith Smillie)

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Shameless self-advert: I once did sort of a comprehensive write-up on the LGP-30

Regarding the PiDP-1: I do plan to do a PDP-1 programming course as a series of blog posts (free of charge, of course).

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I think a generic emulator might be better blog choice, that I can get for free.
The PiDP 1 looks to have a nice front panel, it is just unfortunate it can’t be
adapted for the full line of DEC’s 18 bit controllers. Unix and the PDP 7
comes to mind.
I don’t think the PiDP will sell unless you have Space Wars console of some kind.

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I’m pretty sure they have thought of making Spacewar! run appropriately. It’s the selling proposition!
If you have a look at Hackaday, they have a PCB for CHM-style Spacewar! controllers (much like it’s found on the Space Duel arcade game) ready:

Regarding any extensions: the control panel appears to feature memory extension. I’m not aware of any extensions other than the Type 15 memory extension that would require any presence on the control panel. Sequence break has a panel of it’s own. (This is also seen on some images of PiDP-1 prototypes, so should be accounted for, as well.)

(The only limitation set by this is that it should be difficult to implement the BBN prototype-style memory scheme with data and instruction fields, which features some dedicated controls. But any software for this should be really rare. Also, this addressing scheme requires a few extra instructions, which are mostly undocumented.)