20 Jun
2013
20 Jun
'13
2:57 p.m.
Tony Duell wrote:
The RK11-D (and the RK11-C, 4 rows of flip-chip
modules) does full 18 bit
addressing on the Unibus. Of course Unibus machines with 22 bit memory
addresses still only have 18 bit Unibus addresses with the Unibus Map
between the 18 bit peripheral-genrated Unibus DMA addresses and the
mmory. So I asusme the RK11-D works in any Unibus machine.
For PDP-11 systems without a Unibus Map, but which have 4 MB of memory,
it should be possible to use a bounce buffer. I imagine that the
overhead may be
rather high since I have done that for the RX02 floppy drive on a Qbus
system
under RT-11 for a Mapped Monitor. The first version was for a PDP-11/73
system, but when it was tested using a PDP-11/23 CPU, the interleave time
between sectors was not sufficient to transfer the data to and from the user
buffer if the transfer was done, for example, before starting the next
read into
the silo. That caused the interleave interval to be exceeded and the
transfer
rate was rather slow. I would image that since the RK05 must have a much
higher transfer rate, there would be even more of a problem.
Jerome Fine