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Aucbvax.2254 fa.unix-wizards utzoo!duke!decvax!ucbvax!Mike@BRL Sun Jul 12 22:58:31 1981 More ENABLE/34 Info... From: Mike at BRL To satisfy the requests for more detail, I have abstracted some of the more interesting parts from a paper entitled "Modifications to UNIX to Allow Four Mega Bytes of Main Memory on a 11/40 Class Processor" by Clement T. Cole and Sterling J. Huxley of Tektronix Laboratories:

The ENABLE/34 PARs are indexed by bits 13-17 of the Phys Addr comming out of the CPU. 5 bits => 32 PARS can be used; 8 for Kernel I, 8 for Kernel D, 8 for User I, 8 for User D. The DEC PARs have to be set up to map into different parts of the 18-bit address space. Roughly: KD0-6 KI0-7 UI0-7 UD0-7 KD7 I/O page is the 18-bit layout, allowing the 32 ENABLE PARs to be used to really do the management. The DEC PARs are intialized once and forgotten.

If you hope to use Supervisor Mode, you loose!

Mapped Memory Access time is quoted as Memory access time plus 150 ns. Cache hits access in 110 ns max.

Fortunately, DEC did not assign any other I/O devices resiging at the I/O map's location for non-22-bit machines, so the ENABLE Unibus Map appears identical to the DEC 11/70&44 one. No speed quotes are given, so you probably also suffer the 90-100 ns delay for NPR address mapping, same as the 11/44&70.

"Unfortunately, it was found that the ENABLE board can not be running in 22-bit relocation mode with I/O mapping turned OFF. These two bits should be independent of each other..." == Hardware glitch. A software kludge can get around this.

Just to show something, Clem ran some benhmarks, which due to time limitations, can not properly show off the benefits of the ENABLE. The benchmark is a recompilation of their UNIX Kernel... With all that extra memory, a 60 buffer block cache in UNIX would have made worlds of difference...

CPU Real User Sys ================================ 11/70 13:06 5:03 3:12 11/44 23:35 7:42 6:39 11/34 58:23 17:12 13:08 34+ENAB 42:19 14:42 10:29

These results I suspect as being rather pessimistic -- see the paper for details.

Putting the Able 8K cache on an 11/34 makes a big difference. This remains true for the ENABLE/34.

For those interested in prices: ENABLE/34 -- $5,500 ENABLE CACHE-$3,750 and you should pay no more than $4,500 for a single board 0.25Mbyte 22-bit memory board.

I know nothing more about the hardware -- call Able at (714)-979-7030 and pester them. If need be, ask for Ken O'Mohundro ("The UNIBUS Wizard").

Personally, I think that this is the shot-in-the-arm that our aging 11/34s and 11/40s needed, for those of us who don't have the luxury of replacing all our 11's with VAXen. Happy Hacking! -Mike Muuss

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