🚀 go-pugleaf

In article <564693993wnr@stuffing.demon.co.uk>
           neil@stuffing.demon.co.uk "Neil Matthews" writes:

>In article: <816018081snz@wookie.demon.co.uk>  John Beardmore 
><wookie@wookie.demon.co.uk> writes:
>> 
>> In article <754853600wnr@stuffing.demon.co.uk>
>>            neil@stuffing.demon.co.uk "Neil Matthews" writes:
>> 
>> >System is 486 dx2/66, Award BIOS, VLB, CD-ROM, SBPro, 2*420Mb HD, 
>> >Avance Logic video, DTC 2278 EIDE/multi I/O card, etc.
>> >Recently upgraded memory from 12Mb to 16Mb, now get frequent crashes of
>> >kernel32 which lock up the machine completely. The only way out is to 
>> >power down. Any suggestions as to why this might be happening?
>> 
>> Well, if your memory has no parity, you won't be getting any warning of
>> memory problems beyond unexplained crashes !
>
>It seems like some has, some hasn't.
>The installed memory is as follows:
>
>4 * 1Mb 30 pin SIMMS 3-chip (2 * 51C4400, 1 * 51C4100 CJB7) 
>(I assume that's 4bit+4bit+1bit @ 70ns)
>1 * 4Mb 72 pin SIMM (8 chip, 60ns, no parity?)
>1 * 8Mb 72 pin SIMM (NEC, 16 * 424400-70L, 8 * 421000-70L)
>(Again, I assume 4bit+4bit+1bit @ 70ns)
>
>Is parity checking one of those things the bios does automagically?

It's done in hardware though there may be BIOS configuration to enable or
disable it.


>Will it try even if some of the mem is n/p?

Depends on the BIOS. Maybe not.

Some boards won't check parity even if you give them all partiy memory.


>> I'd accept the hit of some downtime and do some serious memory checks.
>
>What do you suggest? 

Checkit or Sleuth for a start, though by now I'd expect to see some good
stuff in Simtel or where ever.

 
>> If you are certain that the other simms are OK, you could pull them out
>> to speed things up,
>
>I guess you mean "speed up the memory checking". 

Indeed.


>> but if the problem has any contribution from things
>> like bus loading, that may give you a false positive...
>
>Ain't life a bitch!

Mr Hizenburgs revenge...

 
>> Does adding an extra wait state in your bios config help ?
>
>My Award bios has a setting for dram speed - the options are slowest, 
>slower, faster, fastest. The default is faster. Any idea what these refer 
>to in real access time?

No, that sounds astonishingly innumerate !


>  (I've set it to slower to see what happens.) 
>Default wait-state is 1, left it at that for now.

Do those wait states refer to memory access ?  It would seem odd to offer
configuration of the number of wait states as well as this slowest, slower,
faster, fastest stuff.


>> Did you get the right type of RAM ?
>
>Is there a wrong type? (see above)

Absolutely.  There can be.

Once you've got the number of pins right there is write per bit, static
column, page mode, fast page mode, EDO and EDRAM variants to worry about.

Many of these are backwards compatible to each other but some OEMS have
frequently strayed off the path of bog standard DRAM in the quest for a
little extra performance. ( AST spring to mind ! )  Most 3rd party developers
don't do this as it makes them vulnerable to obsolescence and glitches in
supply.

-- 
John Beardmore