Changes
/* Technical */
Holding the PCB so that the mouse port is to the top-right, the following, which is not easy to see from the photos, is written on the PCB:
1. Upper left says "DATEL" 2. Lower middle says "CPC464 MOUSE 5/89" (The 5 is not legible, could be a 6) 3. To the right side are 6 connection points. From to bottom these are labelled 0 (or 8 not easy to see), 4, 3, 2, 1, 6.
The following ICs are inside interface: