B
Bob Niland
I'm sure that PCI-E also fixes the voltage problem
TAS: > It's not that they're uneconomical.
I was going to write that at one time, and discovered
that someone had done it. I no longer have a reference.
Agreed, and it also doesn't define hot-swap slots,
but that hasn't prevented people from implementing
them. If the architecture is slot-per-bus, with
local power management support logic, the connector
can include a sensor for the voltage keyways of the
card, and configure itself. Clumsy. Expensive.
But not impossible.
I worked for a computer maker that went all-3.3v
"prematurely" and had to add 5V slots back in later.
There's some dissonant stuff out there yet, like
SCSI-160 cards on 133MB/s PCI 5v/32bit. And we're seeing
it repeated with SATA-160 PCI cards that are only 133
at the backplane.
Tell me about it. I sold my last PCI-4x SCSI cards on
eBay last year, as it became apparent that no consumer
motherboards were ever likely to get 64b or 66MHz PCI
slots.
Like I said, PCI-Express fixes this, but it might not
have been necessary for a few years yet, if Parallel PCI
had had a more compelling migration plan. USB and FireWire
evidently learned from the PCI experience, and avoided
the trap. Presumably PCI-E can eventually grow link speed
as well.
TAS: > It's not that they're uneconomical.
They simply don't exist.
I was going to write that at one time, and discovered
that someone had done it. I no longer have a reference.
The PCI standard does not define universal slots.
Agreed, and it also doesn't define hot-swap slots,
but that hasn't prevented people from implementing
them. If the architecture is slot-per-bus, with
local power management support logic, the connector
can include a sensor for the voltage keyways of the
card, and configure itself. Clumsy. Expensive.
But not impossible.
The intended migration path was ... hosts could switch
to 3.3V signaling. There was never any
intent of offering dual voltage host slots.
...
What has actually happened, ...
I worked for a computer maker that went all-3.3v
"prematurely" and had to add 5V slots back in later.
There's some dissonant stuff out there yet, like
SCSI-160 cards on 133MB/s PCI 5v/32bit. And we're seeing
it repeated with SATA-160 PCI cards that are only 133
at the backplane.
... that consumer boards never even took advantage
of the real no-brainer for PCI performance improvement,
64-bit slots.
Tell me about it. I sold my last PCI-4x SCSI cards on
eBay last year, as it became apparent that no consumer
motherboards were ever likely to get 64b or 66MHz PCI
slots.
Like I said, PCI-Express fixes this, but it might not
have been necessary for a few years yet, if Parallel PCI
had had a more compelling migration plan. USB and FireWire
evidently learned from the PCI experience, and avoided
the trap. Presumably PCI-E can eventually grow link speed
as well.