This is the A3020/A4000 Econet module. It is very slightly longer than the Master version but not quite as wide. The connecting pins are at the very edges of the board unlike the Master module which has the pins inset a little. In fact, the distance between the pins is identical in both modules making them interchangeable but it is the board size which is different.

All the components except the 68B54 have been replaced with surface mount versions.