Speed of PCMCIA slot?

[hamburglar]

Does anybody know the transfer rate of the PC Card/PCMCIA slot? Is it over 400mb/s so a firewire would get full speed, theoretically? Thanks

 

[Peter]

You're dreaming. PCMCIA (read: PC-Card 16) is a hot pluggable incarnation of ISA. 2 MBytes/s if you're lucky.

CardBus essentially is PCI, building a CardBus FireWire adapter would make sense.

regards, Peter

 

[Shalmanese]

PCMCIA and CarBus are used pretty much interchangably now so I would be assuming he means CardBus. I think Cardbus is a bit slower than PCI since there was some issues with building a Cardbus Video card.

 

[Peter]

The issue with building a CardBus graphics card is the requirement for VGA legacy compatibility.
I'm not sure, but I think PCI-to-CardBus bridge chips do not have that stupid old VGA resource
forwarding feature like normal PCI-to-PCI or -AGP bridges do. I can check on that if you want 🙂

Other than that, a PCI-to-CardBus bridge chip is essentially a special flavor of PCI-to-PCI bridge, with
hot plug support and an equally braindead backward compatible mode *sigh* for PC-Card-16.

PCMCIA btw is the name of the committee, the name of the standard is PC-Card.

regards, Peter

 

[AndyHui]

Hhmm...I thought I answered this question a few hours ago?

Oh yes, I did. Here's the answer...

<< 16-bit PCMCIA: ISA bus bandwidth (can't remember).

32-bit CARDBUS: PCI bus bandwidth (133MB/s).

Please read the FAQ: What's the difference between PCMCIA/CardBus/Type II/III, etc? >>



The reason why you won't have a PC Card VGA unit is because the PC Card slots require drivers to be loaded before they are active. In otherwords, you need the OS to be loaded before the PC Card slots can be used. You need VGA before the OS is loaded. The only way that you can get around this is by special BIOS support, much like USB Mice and Keyboards. Since no one actually uses PC Card VGA units, BIOS support is never going to happen, especially now that you have relatively high-powered solutions like the GeForce 2/4 Go and the Radeon Mobility.

 

[Peter]

I checked - PCI-to-CardBus bridge chips do have VGA resource forwarding. So technically VGA-on-Cardbus
is feasible. It's not going to happen though, not so much for the lack of BIOS support (that wouldn't be
too hard to add, after all VGA behind PCI-to-PCI bridges is supported already), but much more because
you can't do a useful VGA in a cardbus card. Physical space, power allowance, thermal properties ... you'd
end up with a pretty ridiculous thing easily outrun by the worst of chipset integrated shared-memory VGA
ever done.

regards, Peter

 

[AndyHui]

Hey Peter....

I thought these guys were dead....

Appian Traveler PC Card. I haven't heard from Appian for years.