From: Mark Bell (bytehead_at_bellatlantic.net)
Date: Sun Oct 03 1999 - 20:46:28 EDT
At 01:09 PM 10/03/1999 -0700, Vincent Poy wrote:
>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.
Let alone even requiring the elder XT bus technology. POTS lines have
serious limitations, and as fast and as furious as modems have advanced, it is
still a drop in the bucket compared to a LAN connection. I routinely go to
gaming conventions, and the one thing I love seeing is people who have never
played games or transfered files on a LAN before (They literally buy a network
card the day before or hope to buy one at the CON). They don't realize how
slow their modems are! :)
>
>> 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.
No, the new spec calls for total abolishment of the ISA slots and only PCI
slots from now on. Now, of course, manufacturers can break rank, but this is
the first time that Microsoft and Intel have officially banished ISA to the
land of dead technologies when drawing up their yearly PC spec. All previous
specs included allotments for inclusion of ISA slots. Yep, ISA cards are
still
produced. My Sportster 128k ISDN Adapter is ISA.
>> 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.
On a good day, no traffic, full duplex, even a switch connection if you
want (non gigabit). Theoretical, maximum bandwidth so we can ascertain if
peak conditions are containable within bus standards. >;P I really was
not targeting differentiating conditions of the NIC vs. shared bandwidth,
switch connection, or duplex mode. If someone wants a breakdown on network
topological design, email me. <g>
>
>> 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.
Sustained vs. Burst. Burst conditions *are* realized from time to time and
the network would feel the pinch during those moments. You can always
construct scenarios to utilize full bandwidth (RamDisk comes to mind along
with burst, and large cache controllers (SCSI)). On a network I consulted,
an Access Database MDB was on the back end (~80megs in size) in a RamDisk for
optimal speed for client access. The point is to realize the maximum limits
and construct
similar, potential loads (load balancing/load min/load max). If we were
to network a bunch of PCI machines running 8-bit SCSI HD adapters vs. 512meg
RamDisks used for optimized network traffic or controllers with large caches,
we could see bandwidth waste vs. full saturation quickly. When I found out
they
opted to cache their entire MDB in a RamDisk on their server for maximum
speed, I was pretty amazed. I thought it was an interesting approach to
client/server applications! (They had a UPS just in case along with a software
controlled procedure to backup the MDB if power went out :)
I always wondered why 3Com never warned users of their PC Card solutions, yet
warned them of the 3C515TX series 10/100 ISA adapters. The 16-bit PC Card
spec has a theoretical limit of ~7.84MB/sec.
>> 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.
Hehe. :) That's an interesting way of doing things! I should look into
evaluation/trade-up programs more closely.
>
>> 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.
Only reason I used Telebits and their PEP protocol was to retrieve
Usenet/email
traffic for a BBS back in 1991-2. Wasn't PEP rated at 19.2k? (Maybe I
missed something, but I wasn't the biggest Telebit fan in the world. You're
probably
way more up on the spec than I....)
My traffic carrier didn't offer HST connections for the traffic, and after
seeing how
LARGE the downloads were, I could completely understand why. I agree with
their
superiority (Telebit), but all the local BBS's and even the LD ones I
called were USR/HST (HST was asymmetrical,
ugh). Wow, that's interesting you were one of the first people to test
early implementations
of their modem products back then. In 1987, I couldn't afford anything
close to
top of the line. To be able to beta test modems from the big boys (Hayes was
huge then, but their Ultra 9600bps proprietary protocol failed badly, IMHO).
I relied on my 300bps modem of power for years until I saved for a more
powerful
USR/HST tower of power. On a BBS level, USR reigned surpreme
for years. I couldn't believe how fast that 2400/9600HST "round light" model
of modem I had was! I've stuck with USR products ever since then. My last
HST dominant connection period was their their 16.8 variant of the protocol.
That was their last hurrah. Heck, I use a Courier V.Everything now when I
have to do modem communications with my desktop.
-------------------------------------------------
Mark Bell @ ElectroSoft Consulting
800 College Drive #126 * Vineland, NJ * 08360
Voice: 609-293-9426 =-= Fax : 609-293-9423
Email: bytehead_at_bellatlantic.net
-------------------------------------------------
Providing MS Access, SQL, Visual C and Basic
RDBMS solutions to satisfy your database needs.
Network and System consultation and installation
--------------------------------------------------
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