[Info-vax] Alpha CPU revision & serial number, blank?

[Johnny Billquist]

On 2011-12-22 14.31, Paul Sture wrote:
> On Thu, 22 Dec 2011 12:44:33 +0100, Johnny Billquist wrote:
>
>> On 2011-12-21 18:15, Paul Sture wrote:
>>> On Wed, 21 Dec 2011 09:02:32 -0600, Bob Koehler wrote:
>>>
>>>> In article<4ef11a62$0$6943$e4fe514c at news2.news.xs4all.nl>, MG
>>>> <marcogbNO at SPAMxs4all.nl>   writes:
>>>>>
>>>>> My guess is that the revision and serial number information was
>>>>> mostly added there to identify IA-64 (and possibly later Alpha)
>>>>> processors?
>>>>
>>>>      The serial number of a VAX 11/780 was readable from the system ID
>>>>      register.  I haven't seen such since VAX-11, but I'd not be
>>>>      surprized if it was there on an 8000 series VAX with an SBI.
>>>
>>> Didn't all 750s have the same ID?
>>
>> I don't think so. But it was probably not hard to change. It was
>> probably some wirewrap, jumpers or switches somewhere. Part of the SID
>> was fixed (the high byte), but the rest was implementation defined.
>>
>> Checking a little, it seems as if the SID of the VAX-11/750 actually
>> holds hardware and ucode revision numbers. So I'd say that there wasn't
>> properly a serial number, but it also wasn't necessarily the same for
>> all machines.
>
> When I was using 750s that all came from one OEM I thought it could be
> down to that particular OEM, but hardware and ucode revision numbers
> would definitely explain why they all looked the same to me.
>
> It's a long time ago, but I'm pretty sure I'm talking about the value
> returned by f$getsyi("SID").

I *think* that is normally used to just check the CPU type, which is the 
high byte of the SID, and which is the same for all VAX-11/750 machines. 
(And the value is 2, if I remember right.)

The ucode revision number is used by alteast Ultrix (and NetBSD) to 
actually patch the microcode of the CPU if the revision has some known 
issues. I would guess VMS do as well. The ucode patch was distributed by 
DEC for Ultrix, and adopted into NetBSD where it lives to this day.

	Johnny