info-vax (03/30/83)
>From GEOFF5@SRI-CSL Wed Mar 30 05:58:36 1983
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Via: UMCP-CS; 27 Mar 83 3:38-EST
Remailed-Date: 29 Mar 1983 1743-PST
Remailed-From: the tty of Geoffrey S. Goodfellow <Geoff5 at SRI-CSL>
Remailed-To: Info-VAX: ;
DEC now offers a 450 megabyte winchester for a very reasonable
cost. Only problem: it is a Unibus only device.
My question is, what kind of load does putting several of these
put on a unibus? Should one buy a unibus for each (kind of eats
into the cost..). The Vax configuration guide that comes with
BErkeley Unix says that massbuss disks are a waste since most
disks can't even xfer a unibus speeds anyway (according to their
calculations, not even the touted RP07 talking to interleaved memory).
I am looking now at configuring a 780 system with NO massbusses.
Advice, anyone?info-vax (04/02/83)
>From GEOFF5@SRI-CSL Sat Apr 2 09:36:53 1983
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id AA04249; 2 Apr 83 09:38:20 PST (Sat)
To: mark.umcp-cs@UDEL-RELAY.ARPA
Cc: info-vax@SRI-CSL.ARPA, unix-wizards@SRI-CSL.ARPA
In-Reply-To: Message of 30-MAR-1983 03:41 from Mark Weiser <mark.umcp-cs@UDel-
Remailed-Date: 31 Mar 1983 1759-PST
Remailed-From: the tty of Geoffrey S. Goodfellow <Geoff5 at SRI-CSL>
Remailed-To: Info-VAX: ;
The figures displayed at DECUS about the UDA50a controller disks indicated
that one UDA50 controller uses ~52% of a Unibus [someone will no doubt no cite
the exact figure] and has an explicit "Thou Shalt Not Steal All The Unibus
Cycles" built in to insure that figure. Thus if you decide to get more than
one CONTROLLER (up to 4 disks each) the recomendation was to get a second Unibus.
The UDA50a also should not be put in the same Unibus with "high performance
DMA devices" without testing the loads involved. Note that terminals and
DMCs are not considered "high permformance DMA devices". If we get one it
will go into the main Unibus cage and if we get a second it will go into
the second Unibus as would a third (although I doubt we need 6+ disks.)
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