21 Sep
2015
21 Sep
'15
10:20 a.m.
On Sep 21, 2015, at 12:47 PM, Johnny Billquist <bqt
at update.uu.se> wrote:
...
Way more primitive is a polite way of putting it. Just like all other PRO controllers DEC
ever built, it uses programmed I/O. The curious thing is that the PRO bus actually
appears to support DMA, but it was never used, not even for the hard drive or network
interface. All those devices do I/O to on-card memory, and then the driver has to move it
to/from host memory.
I haven't tried this, but the PRO technical manual (on Bitsavers) shows that (a) there
is no way to do formatting, but (b) you can configure the controller to accept, for
reading but not writing, various non-RX50 formats.
paul
I suppose you could on a Pro, since that had its
own particularly disgusting junk controller. But I haven't seen RX50 formatting
there. My impression was that they came factory formatted, with the DEC-specific 10
sector per track format.
Ugh! The PRO controller probably was weird enough to not allow you, even though as far as
I understand, it was also way more primitive than MSCP.