From: Vincent Poy (vince_at_victor.MCESTATE.COM)
Date: Sun Oct 03 1999 - 16:09:48 EDT
On Sun, 3 Oct 1999, Mark Bell wrote:
> 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).
Yep, a modem doesn't even use up 5% of the bandwidth of the ISA
bus.
> 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).
That alldepends since I think there will still be atleast 1 or two
ISA slots since there are some cards that are still ISA now like my
Terratec EWS64 Soundcard which is supposed to be high-end.
> 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 " " " "
You forgot that there is half duplex and full duplex.
> 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..."
The bottleneck isn't in the bus but with the speed of Hard drives
since no HD can write at 12.5MBytes/sec sustained. 3Com never warned
anyone about the 10/100Mbps not giving any speeds better than 10Mbps for
the PCMCIA version.
> 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.
Yep, that was why I sent my 3CCFEM556B which is PCMCIA and got
a 3CCFEM656B after a year. I actually made $100 from 3Com in doing that
since the PCMCIA version costed close to $400 last year and the CardBus
version is $229 with rebates.
> 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.
I'm actually a fan of Telebit more than USR since the PEP days
back in 1987 when I was one of the first persons who tested Telebit, USR,
Hayes modems before there was even a 9600 standard. Telebit was more
robust and 18k compared to HST which was only 9600. That's why even in
Austraia when there were regulations that all modems were Telebit.
Concord was the one who came out with v32 in 1989 or 90. I agree with you
that RealPort is a neat idea except for the size of the thing and also the
modem isn't as good as 3Com's. Intel has the best networking cards though
but the only problem is that their PCMCIA offerings are based on Xircom's
guts and their modems are Xircom's as well.
Cheers,
Vince - vince_at_MCESTATE.COM - vince_at_GAIANET.NET ________ __ ____
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