-----Original Message-----
From: Megan [mailto:mbg_at_world.std.com]
Sent: Tuesday, November 09, 1999 10:24 PM
To: Discussion re-collecting of classic computers
Subject: Re: RT11 V5.7 + RA92 = ?
>for a nice writeup of how the rules work). Unfortunately the RT-11
>developers chose to ignore these rules in picking their "default" second
>CSR for RT-11, but of course you could choose to follow these rules
>by ignoring the SYSGEN-suggested secondary (and tertiary and whatever
>comes after) DU CSR's.
Okay, as one of the developers involved with RT-11 at the time the
DU handler was first developed after we actually got some prototype
MSCP controllers, I have to respond...
At the time we got the controllers, the primary address had already
been defined, but the secondary and subsequent addresses were assumed
to be allocated out of the floating CSR and floating vector areas. It
wasn't until some later time that it was decided that the secondary
and subsequent addresses were to be fixed and had a certain algorithm
for determining. By that time, SYSGEN had already been modified. It
was decided that 1) for backwards compatibility and 2) since the addresses
can be changed with SET CSRn and VECn, SYSGEN wouldn't be changed.
We didn't ignore the defaults, there were none at the time to ignore.
Finally, there is the problem of the SBC-11/21[+], where the 'standard'
MSCP address is actually in a pre-allocated area, so it has to be
located elsewhere (176150)...
Megan Gentry
Former RT-11 Developer
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| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
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Received on Thu Nov 11 1999 - 07:57:38 GMT