11 Feb
2019
11 Feb
'19
10:31 a.m.
From: Jerry Weiss
Though not a disk controller, the DEC DR11-B/DA11-B
would not cross 64K
boundaries.
Interesting! What's odd is that the DR11-B uses the Bus Interface card (M7219)
from the RC11 controller, and that _can_ cross moby
boundaries, so clearly it
has the right overflow output; someone just decided not to
implement it - the
DR11-B sets ERROR instead on an address overflow. Wierd.
Anyway, it will be interesting to see if RSTS operates correctly once this
problem is fixed...
Noel
11 Feb
11 Feb
12:22 p.m.
On 2/11/19 12:31 PM, Noel Chiappa via cctalk wrote:
??? Yes the overflow sets
error and halts the transfer.? There are
registers for the extended bits in the DR11B, just missing a few gates
to increment. ? My recollection is that my simple mod wouldn't allow the
read back of the incremented extended bits, but in my use case this was
never a problem.
From: Jerry
Weiss
Though not a disk controller, the DEC
DR11-B/DA11-B would not cross 64K
boundaries.
Interesting! What's odd is that the DR11-B uses the Bus Interface card (M7219)
from the RC11 controller, and that _can_ cross moby boundaries, so clearly it
has the right overflow output; someone just decided not to implement it - the
DR11-B sets ERROR instead on an address overflow. Wierd. Anyway, it will be interesting to see if RSTS operates
correctly once this
problem is fixed...
Noel
Yes if turns out the increment was not functional for one or both
extended address bits, it is impressive that UNIX booted successfully
without tripping over a boundary.
????????? Jerry
2142
days inactive
2142
days old
1 comments
2 participants
participants (2)
-
jnc＠mercury.lcs.mit.edu -
jsw＠ieee.org