From: Mark Bell (bytehead_at_bellatlantic.net)
Date: Sun Oct 03 1999 - 18:41:30 EDT
At 11:08 AM 10/03/1999 -0700, Vincent Poy wrote:
>On Sun, 3 Oct 1999, James Lai wrote:
>
>> How much faster is Cardbus comparing with 16 bit cards in reality? Anyway
>> numbers or findings??
>
> Well, think of it like PCI (CardBUS) 32bit versus ISA (16bit
>PCMCIA). 16Bit is cable of doing I think 12Mbps max so even if you had a
>100Mbps card, you can only get 12Mbps out of it. The CardBUS 100Mbps card
>will do full speed since 32bit can handle up to 133Mbps. The only thing
>is that modems can run on PCMCIA just fine but FastEthernet is another
>story.
For modems, it doesn't make a difference, as it would never even come close
to using all the bandwidth 16-bit (AT) ISA technology has to offer let
alone even
8-bit (XT) (singular), ISA slots. A 32-bit cardbus modem will not yield better
performance than a 16-bit PC Card device. (A theoretical POTS analog line
connection at 53kbps = .053mbps = .00625MB/sec).
In addition, based upon the PC99 spec whipped up by the WINTEL monopoly <g>,
ISA is slated for total removal in the next wave of PCs (Meaning your next
PC will NOT have ISA slots).
The 16-bit PC Card spec is based on ISA (AT).
The 32-bit Cardbus spec is based on PCI.
Mb = megabit
MB = Megabyte
XT = eXtended Technology
AT = Advanced Technology
ISA = Industry Standard Architecture
PCI = Peripheral Component Interface
Network cards? Ouch time...
10mbps = 1.25megabytes/sec (On a clear day with NO traffic elsewhere)
100mbps = 12.5megabytes/sec " " " "
Now,
32-bit AGP = 66mhz x 32-bit (4bytes) = theoretical 264megabytes/sec
32-bit PCI = 33Mhz x 32-bit (4bytes) = theoretical 132megabytes/sec
16-bit ISA = 8mhz x 16-bit (2bytes) = theoretical 16megabytes/sec
8-bit ISA = 4.77mhz x 8-bit (1byte) = theoretical 4.77megabytes/sec
That 16MB/sec is really like 8MB/sec because of a clock cycle used for
addressing. Real world bandwidth would be ~5MB/sec (40mbps) or potentially
even less, but you have to remember this technology was introduced back
when the IBM PC AT 80286 tower of power was out (6+mhz of breathtaking
speed back in 1983!). That is why companies like 3Com warn you with their
ISA based 10/100mbps ISA cards that don't expect transfer rates even close
to 100mbps. ISA solutions are offered for legacy support, and I've seen
my fair share of corporate users with 486 ISA only IBM/ValuePoints flip
OUT when their network connects seem, "so slow..."
With networking, if you use 10bT only, then 16-bit PC Card technology
is fine (They tried to do away with, "PCMCIA," to replace it with
"PC Card," but I have, "PCMCIA" stuck in my head usually <g>). But if
you have an eye on the future, and your notebook supports 32-bit Cardbus
technology, go in that direction.
Personally, I am a fan of USR's modem datapumps since the HST days, and I tend
to stick with 3com/usr/megahertz solutions for my computing needs. I
used a Xircom IIps PCMCIA 10mbps adapter before, and it worked just
fine, but I've always been a USR zealot. For my modem and network
solutions, I stick with Xjack devices. I think the RealPort is a neat
idea, but I need a Type II slot open because I routinely use a 1480
SCSI Adapter on the go.
Mark
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Mark Bell @ ElectroSoft Consulting
800 College Drive #126 * Vineland, NJ * 08360
Voice: 609-293-9426 =-= Fax : 609-293-9423
Email: bytehead_at_bellatlantic.net
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