[Info-vax] DEC Multia (UDB) issues

[glen herrmannsfeldt]

In comp.os.vms Steven Schweda <sms.antinode at gmail.com> wrote:

(snip)
>   Really?  The oldest/lamest Alpha system I ever used was an
> AlphaStation 200 4/233.  Its approved memory was fast-page
> mode, parity.  (According to its "User Information" book,
> "The system requires 72-pin parity SIMMs that have an access
> time of 70 ns (nanoseconds) or 60 ns.")  But those extra
> "parity" bits were aggregated for use as ECC, not for simple
> parity.  One extra bit for each eight data bits means four
> extra bits for a 32-bit word, which is enough for ECC.  

No, but 8 extra bits for a 64 bit word is enough for ECC.
If the processor doesn't do that, then the cache probably does.

> The
> last VMS system I saw which used parity memory as parity
> memory (and not as ECC memory) was a MicroVAX II/III or a
> MicroVAX/VAXstation 2000.  I've never seen any machine which
> used standard parity SIMM/DIMMs as anything other than ECC.

-- glen