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(Note: photo is of an Issue 1.0 Mainboard)
Having seen my System Keyboard in an Electron case somebody asked if it was possible to build an Atom into an Electron case ? So I thought about it and then did it !
Perhaps this is more a clone than a replica though ? It is functionally the same as an Atom, though I have made a few 'upgrades' to more available parts:
the 24 2114 RAM ICs have been replaced by an 8K (video) and 32K RAM ('text' space)
the OS ROM is replaced by a 16K EPROM which has additional space for BASIC with Floating Point and DOS
the Utility ROM (e.g. for NFS) is replaced by a second 16K EPROM with links allowing selection from four different images (Issue V1.0 Boards have a 2732 fitted)
the YPrPb outputs have been beefed up with the addition of a video driver
the Alan Knowles screen noise eliminator has been incorporated
A complete replica Atom comprises three PCB's - a Mainboard, Keyboard and optionally a Floppy Disk Controller (FDC) Board.
The Replica Atom Mainboard will fit in an Electron Case in the space occupied originally by the Electron's mainboard, I managed to fit an Econet interface onto the board as well. The FDC Board fits where the Electron power supply board was and also includes a GOTEK.
There are three variants of keyboard, one that fits in the place of the Electron Keyboard, a second which is intended for a non-cased build (this will not fit in an Electron case) and a third which fits in an Atom case. The 'Electron' variant reuses the original Electron key switches (plus a few extra) , the second uses Cherry MX switches, so you don't need to scrap an Electron to build one of these ! The third keyboard uses BBC Computer key switches and can be fitted in an Atom case (please note this board is designed to accept the white Futaba switches, later types may not fit ?).
The original intention for this project was for it to be built into an Electron case as Electrons are widely available and not too expensive whilst original Atom cases are very rare indeed and would demand a high price. However with the availability of a 3D printed Atom case design (see https://stardot.org.uk/forums/viewtopic.php?t=23567&hilit=atom+3d+print) it seems many are building these boards into an Atom case after all so I have now made available an Atom case compatible keyboard that uses the BBC key switches as in the later version Atoms.
Here are a couple of pages with info on construction:
Memory Map
OSROM Image - COS/DOS/BASIC and FP
Econet ROM