RT-11 DY install
Pete Turnbull
pete at dunnington.plus.com
Thu Oct 18 11:29:46 CDT 2018
On 18/10/2018 13:22, Don Stalkowski via cctalk wrote:
> On Wed Oct 17 19:19:20 2018 cctalk at classiccmp.org (Jerry Weiss via
> cctalk) wrote:
>> Note: Apparently the RY emulation won't load if more than 256K
>> memory is specified as the DEC hardware did not support DMA in a
>> 22bit box. I'm=20 entirely not sure why SIMH has to
>> enforce this as its possible to work around (e.g. TSX+ supports
>> buffering the IO). Anyone know how to override and load in
>> SIMH?
>>
>> Jerry
> Thanks Jerry. That's "fixed" it. Since simh didn't complain about my
> "set ry enabled" I assumed (wrongly) that that wasn't the issue.
>
> Thanks to all the other's who replied.
As Noel pointed out, real PDP-11s definitely work with RX02 subsystems
in 22-bit systems. SIMH really ought to be able to do so regardless of
18-bit or 22-bit memory. The DY driver in RT-11, for example, simply
knows to only use the bottom 256K for DMA I/O.
--
Pete
Pete Turnbull
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