the life & times of 06-ALA01-0006180
The MRB upgrade gives the Electron three states, each selectable by a switch on the side of the computer:
Normal mode (functions as a from-the-factory vanilla Electron)
Turbo mode (gives a significant speed increase that is useful with a lot of software)
64k mode (increases the available RAM, to, for example, allow limited compatibility with BBC B software.)
Some work has begun over at Andy's Arcade to see which Beeb games work on a 64k Electron.
I've done a video doing a comparison of a Beeb program running on BeebEm and also on my Elk in 64k mode with the Jafa Mode 7 Simulator ROM running.
The Acorn Electron is an 8-bit microcomputer, running the Acorn MOS v1 Operating System. (Switch on and it is all there, instantly...) The Elk ran from a 6502A processor at "2MHz when accessing ROM and 1 MHz/0.5897 MHz when accessing RAM" (source Wikipedia).
Interface options on the 'vanilla' Electron came limited out of the box, but the expansion bus on the back of the machine opened up vast possibilities for development, as I hope this website goes some way to show...
My original Electron remained intact right through the 80's; the major changes have only really taken place to it since I settled in my current home and the Elk came down from slumber in storage ;-)
I have changed the keyboard a few times, keeping some donor machines for spare parts. In 2014, I bought a bundle from eBay that included an Elk which had been upgraded with the MRB so my original motherboard got swapped our for that.
In reality, Acorn Computer serial number 06-ALA01-0006180 only really applies to my machine in spirit now, as I think only the case remains orginal from my machine in the 80's! This is fairly inevitable though, when you consider the age of the computer and the amount of use and abuse it has had and all the upgrades. In heart, it is still that original machine to me.