The 510a has the most bizarre touch screen I've ever encountered. It is a thick, squishy membrane, which distorts the image from the CRT when pressed. Evidently it was not expected to have a long service life, as the User's Guide contains replacement instructions.
The 510a has a one cartridge slot which can accept these cartridges:
The 510a contains a Z-80 microprocessor with what appears to be 48 Kbytes of firmware.
Last updated December 2, 1998
Copyright 1995, 1996, 1998 Eric Smith