the Unix V6 RK pack formatter ... sets _both_
'Format' and
'Read/Write-All
Oooops; my bad; I mis-read the register description. It's setting 'Inhibit Bus
Address Increment' and 'Format', not 'Format' and
'Read/Write-All'. So ignore my
speculation about 'Read/Write-All' not getting the sector header word from
memory.
My bad!
Noel