Dumb question regarding A3KD

[Zac67]

..., another difference was the motor speed, the Amiga floppy runs at half the speed for some reason.

Only the HD drives run in half speed with HD disks. Paula's not able to read/write the doubled data rate required for HD, so they slowed down the disk instead. DD disks run at standard speed.

[Zac67]

The DIP sockets on the left side (U267-274) extend your chip RAM to 2 Megs. You'll need 256Kx4 (e.g. 514256) chips as found on old ISA VGA cards and such.