On 10/17/2018 6:44 PM, Jesse 1 Robinson wrote:
In hindsight I rue the decision to set aside both 4xxx and 5xxx addresses. In
practice, the low order digit is severely underused. In the beginning I thought
that we would need several different 'devices' for each LPAR. Never actually
found a need for more than four, 0 - 3. I like Rob Jackson's idea of assigning
even/odd numbers for gazinta and gazouta, or ranges like 0 - 7 and 8 - F.
Eliminating 5xxx, for example, would free up 4096 addresses for DASD.
It wasn't your fault. It was IBM's recommendation.
The fact is that all but one bit of position 'w' is wasted and position
'x' is nearly always underutilized in the scheme below. However, it's
not uncommon at all to have more than 16 LPARs per processor making
position 'y' too small in today's world.
It works great for small configurations, but should be reworked for
larger environments -- perhaps by combining 'w' and 'x' to a single
nybble and expanding 'y' to two nybbles.
CTC 4-DIGIT NAMING SCHEME: wxyz
w - one nibble to distinguish gazinta from gazouta
x - one nibble that uniquely represents a processor; assigned by you
arbitrarily
y - one nibble that represents an LPAR on processor w, such as LPAR id
from HCD
z - one nibble to complete device address, assigned from 0 up to F
--
Phoenix Software International
Edward E. Jaffe
831 Parkview Drive North
El Segundo, CA 90245
https://www.phoenixsoftware.com/
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