Woo, right - I was searching for a manual for the 6500 series of computers and failing, tried manuals for the 5600 which were at least the same architecture but they didn’t help. But whilst searching I found a Twitter post from 2017 which showed the front of a 6556 with the door open and one dip switch was set differently to mine, so I tried it
@jonn_blanchard Wow really useful to find things regarding dip switches, blind doesn't feel nice or combinations!
@jonn_blanchard
Doing the obscure a bit more often makes it a bit less obscure - so you're keeping the light going there (literally) and for imagination in the coming generation(s) :)