Modem speeds

Modem speeds

Post by Colin Ferri » Tue, 31 Jul 2001 18:01:39



After some info on Modem to Computer speeds.

Most moderm stand alone Modems seen to be able to talk to the computer's
serial port/Atomwide serial card  at 115k, some seem to have problems
and have to drop to half that speed.

Are there any stand alone Modems out there that can use more than 115k
with Atomwide's serial card.

What speed does the 28/33k Acorn Podule modem use?

What does the RiscStation/Mico internal modem use?

What do the TA's use?

Many thanks

--
Colin Ferris Cornwall UK

 
 
 

Modem speeds

Post by Jess Hampshir » Tue, 31 Jul 2001 21:37:31




Quote:> After some info on Modem to Computer speeds.

> Most moderm stand alone Modems seen to be able to talk to the computer's
> serial port/Atomwide serial card  at 115k, some seem to have problems
> and have to drop to half that speed.

That would probably be a limit of the port rather than the modem.
Modern modems need to talk to the computer faster than to the phone line
to allow data compression to work properly.

Quote:> Are there any stand alone Modems out there that can use more than 115k
> with Atomwide's serial card.

> What speed does the 28/33k Acorn Podule modem use?

> What does the RiscStation/Mico internal modem use?

> What do the TA's use?

> Many thanks

--
Jess

icq 91353267        http://www.kentwebnet.com     Using RISC OS 4

 
 
 

Modem speeds

Post by Mark Quin » Wed, 01 Aug 2001 02:41:47


I wouldnt worry too much about the speed between the modem & computer as
your only going to get a maximum of 56K from the modem to ISP

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.265 / Virus Database: 137 - Release Date: 18/07/01

 
 
 

Modem speeds

Post by frui » Wed, 01 Aug 2001 03:33:44





>> After some info on Modem to Computer speeds.
>> Most moderm stand alone Modems seen to be able to talk to the computer's
>> serial port/Atomwide serial card  at 115k, some seem to have problems
>> and have to drop to half that speed.
> That would probably be a limit of the port rather than the modem.

Erm... but that limit is set by the UARTs both in the computer and modem.

Quote:> Modern modems need to talk to the computer faster than to the phone line
> to allow data compression to work properly.

Agreed, but they're limited by the UART speed.

Quote:>> Are there any stand alone Modems out there that can use more than 115k
>> with Atomwide's serial card.

In a recent search the only one I could come up with was a Hayes business
model (Optima IIRC) that was rated at 230400. Hayes have now been taken
over by Zoom IIRC, so I'm not sure on current availability.

I guess it should work OK on the card.

Quote:

>> What speed does the 28/33k Acorn Podule modem use?

At a guess 115200?

Quote:>> What does the RiscStation/Mico internal modem use?

Pass

Quote:>> What do the TA's use?

If they're connected via serial it'll be 115200.

Andy

 
 
 

Modem speeds

Post by Stuart Paintin » Wed, 01 Aug 2001 04:11:03






> > After some info on Modem to Computer speeds.

> > Most moderm stand alone Modems seen to be able to talk to the computer's
> > serial port/Atomwide serial card  at 115k, some seem to have problems
> > and have to drop to half that speed.

> That would probably be a limit of the port rather than the modem.

Not necessarily. Some years ago I was the proud owner of a Motorola
modem that talked quite happily to the serial port at 115200. Sadly,
the modem (and the serial port) suffered damage during a thunderstorm,
so I bought a new modem and a new Atomwide serial port.

The old modem would still accept AT commands at 115200 (despite the
telephone-line circuitry being burnt out) but the new modem didn't
respond at all until I dropped the DTE rate to 57600.

The name of the speed-limited modem: Diamond SupraExpress 56e Pro.

Quote:> > Are there any stand alone Modems out there that can use more than 115k
> > with Atomwide's serial card.

In theory: yes. In practice: probably not :-(

stuart

 
 
 

Modem speeds

Post by Mike » Wed, 01 Aug 2001 03:43:38




Quote:> Modern modems need to talk to the computer faster than to the phone line
> to allow data compression to work properly.

Around four times faster, if memory serves me correctly.

Mike

--
"I'll think of it all tomorrow, at Tara. I can stand it then. Tomorrow, I'll think of some way to get him back. After all, tomorrow is another day."

S O'Hara

A messy kitchen is the sign of a lazy slave.

 
 
 

Modem speeds

Post by Jess Hampshir » Wed, 01 Aug 2001 05:50:28







> >> After some info on Modem to Computer speeds.

> >> Most moderm stand alone Modems seen to be able to talk to the computer's
> >> serial port/Atomwide serial card  at 115k, some seem to have problems
> >> and have to drop to half that speed.

> > That would probably be a limit of the port rather than the modem.

> Erm... but that limit is set by the UARTs both in the computer and modem.

> > Modern modems need to talk to the computer faster than to the phone line
> > to allow data compression to work properly.

> Agreed, but they're limited by the UART speed.

I've never heard of a 28K or higher modem that didn't work at 115k, but
I have heard of acorns that couldn't

Quote:> >> Are there any stand alone Modems out there that can use more than 115k
> >> with Atomwide's serial card.

> In a recent search the only one I could come up with was a Hayes business
> model (Optima IIRC) that was rated at 230400. Hayes have now been taken
> over by Zoom IIRC, so I'm not sure on current availability.

> I guess it should work OK on the card.

> >> What speed does the 28/33k Acorn Podule modem use?

Is it aclually a serial port and modem on a card like a PC one?

Quote:> At a guess 115200?

> >> What does the RiscStation/Mico internal modem use?

> Pass

> >> What do the TA's use?

> If they're connected via serial it'll be 115200.

> Andy

--
Jess

icq 91353267        http://www.kentwebnet.com     Using RISC OS 4

 
 
 

Modem speeds

Post by Brian Howlet » Wed, 01 Aug 2001 05:33:51


On 30 Jul, Stuart Painting stripped and revealed the following:

[snip]

Quote:> Some years ago I was the proud owner of a Motorola modem that talked
> quite happily to the serial port at 115200. Sadly, the modem (and the
> serial port) suffered damage during a thunderstorm, so I bought a new
> modem and a new Atomwide serial port.

> The old modem would still accept AT commands at 115200 (despite the
> telephone-line circuitry being burnt out) but the new modem didn't
> respond at all until I dropped the DTE rate to 57600.

> The name of the speed-limited modem: Diamond SupraExpress 56e Pro.

Interestingly enough that's exactly the same type of modem I've been
using at full pelt on my RiscPC for well over a year now. It more or
less worked straight out of the box, although a little tweaking was
done using some of the AT commands from the manual on CD-ROM and
!Connector.
--
Brian Howlett
--------------------------------------------------------------
Windows has detected that the mouse has been moved.
You must restart Windows for the new setting to take effect...
 
 
 

Modem speeds

Post by druc » Wed, 01 Aug 2001 06:25:29


[Lack of quoting corrected]






>>> Most moderm stand alone Modems seen to be able to talk to the computer's
>>> serial port/Atomwide serial card  at 115k, some seem to have problems and
>>> have to drop to half that speed.

>> That would probably be a limit of the port rather than the modem.
>> Modern modems need to talk to the computer faster than to the phone line
>> to allow data compression to work properly.
> I wouldnt worry too much about the speed between the modem & computer as
> your only going to get a maximum of 56K from the modem to ISP

That is incorrect, when dealing with compressible data such as downloading
news, email and HTML, the modem can achieve up to 4x the line speed. In this
case the serial port speed is the limiting factor, and running the serial
port at over 200KB/s would be desirable. However whether the modem and
computer can support higher speeds reliably depends on both the hardware,
and the OS and applications.

---druck

--
 _   _  _   _  _   _   _   _  
|_)|(_ / ` / \(_  ' ) / \ / \ /|  The Prestige RISC OS Show, 20-21 October
| \| _)\_, \_/ _)  /_ \_/ \_/ _|_   Blue Mountain, taste the difference

 
 
 

Modem speeds

Post by Jeremy C B Nicol » Wed, 01 Aug 2001 11:09:46




Quote:> That is incorrect, when dealing with compressible data such as
> downloading news, email and HTML, the modem can achieve up to 4x the
> line speed. In this case the serial port speed is the limiting factor,
> and running the serial port at over 200KB/s would be desirable. However
> whether the modem and computer can support higher speeds reliably
> depends on both the hardware, and the OS and applications.

Yup; don't Intelligent Interfaces sell high-speed serial ports (which I
assume are much faster)?

--
Jeremy C B Nicoll - my opinions are my own.

 
 
 

Modem speeds

Post by frui » Wed, 01 Aug 2001 16:49:21



> [Lack of quoting corrected]




[snip]

Quote:>> I wouldnt worry too much about the speed between the modem & computer as
>> your only going to get a maximum of 56K from the modem to ISP

> That is incorrect,

Not entirely, the max modem/modem d/l rate will be 56k...

Quote:> when dealing with compressible data such as downloading
> news, email and HTML, the modem can achieve up to 4x the line speed.

...but as you say this could be data compressed by a factor of 4x.

Quote:> In this case the serial port speed is the limiting factor,

Agreed - this seems to top out at around 11k bytes/sec - easily achievable
using a 33.6k modem.

Quote:> and running the serial port at over 200KB/s would be desirable.

and should double the rate to around 22k bytes/sec.

Quote:> However whether the modem and computer can support higher speeds reliably
> depends on both the hardware, and the OS and applications.

Agreed.

Shame we don't have STAC/lzs which can show d/l rates of around 55k
bytes/sec on a 115k serial line :-\

Andy

 
 
 

Modem speeds

Post by Mark Quin » Wed, 01 Aug 2001 17:41:42


Quote:> That is incorrect, when dealing with compressible data such as downloading
> news, email and HTML, the modem can achieve up to 4x the line speed. In
this
> case the serial port speed is the limiting factor, and running the serial
> port at over 200KB/s would be desirable. However whether the modem and
> computer can support higher speeds reliably depends on both the hardware,
> and the OS and applications.

Hrmmm 200/8=25KB/sec
I never saw my modem get past 5KB/sc when I had one and that had a PCI
interface :/

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.265 / Virus Database: 137 - Release Date: 18/07/01

 
 
 

Modem speeds

Post by Michael Hamble » Wed, 01 Aug 2001 21:37:32




Quote:> On 30 Jul, Stuart Painting stripped and revealed the following:

> [snip]
> > Some years ago I was the proud owner of a Motorola modem that talked
> > quite happily to the serial port at 115200. Sadly, the modem (and the
> > serial port) suffered damage during a thunderstorm, so I bought a new
> > modem and a new Atomwide serial port.

> > The old modem would still accept AT commands at 115200 (despite the
> > telephone-line circuitry being burnt out) but the new modem didn't
> > respond at all until I dropped the DTE rate to 57600.

> > The name of the speed-limited modem: Diamond SupraExpress 56e Pro.

> Interestingly enough that's exactly the same type of modem I've been
> using at full pelt on my RiscPC for well over a year now. It more or
> less worked straight out of the box, although a little tweaking was
> done using some of the AT commands from the manual on CD-ROM and
> !Connector.

Same modem here, worked straight out of the box, what tweaking did you need
to do?  I have had nearly 7k/s with it sustained over a, IIRC, 2MB d/l.
Pity my new ISP isn't as fast:-(

Cheers, Mike.....

--
Michael Hambley


http://www.screamager.fsnet.co.uk

 
 
 

Modem speeds

Post by frui » Thu, 02 Aug 2001 03:02:57




Quote:> > That is incorrect, when dealing with compressible data such as
> > downloading news, email and HTML, the modem can achieve up to 4x the
> > line speed. In this case the serial port speed is the limiting factor,
> > and running the serial port at over 200KB/s would be desirable.
> > However whether the modem and computer can support higher speeds
> > reliably depends on both the hardware, and the OS and applications.
> Hrmmm 200/8=25KB/sec I never saw my modem get past 5KB/sc when I had one
> and that had a PCI interface :/

I think you'll find that PCI modems use similar UARTs to external ones,
but ICBW.

Andy

 
 
 

Modem speeds

Post by Brian Howlet » Fri, 03 Aug 2001 02:23:22


On 31 Jul, Michael Hambley stripped and revealed the following:

[...Diamond Supra Express modem...]

Quote:

>> Interestingly enough that's exactly the same type of modem I've been
>> using at full pelt on my RiscPC for well over a year now. It more or
>> less worked straight out of the box, although a little tweaking was
>> done using some of the AT commands from the manual on CD-ROM and
>> !Connector.

> Same modem here, worked straight out of the box, what tweaking did you
> need to do?  I have had nearly 7k/s with it sustained over a, IIRC,
> 2MB d/l.  Pity my new ISP isn't as fast:-(

Well, by default it reports DTE speed rather than DCE. I much prefer to
see 49333 for example rather than 115200 in ArmTCP's status window. I
also fiddled with the volume settings, and once I had it the way I
wanted I saved the settings with the AT&W command.
--
Brian Howlett
------------------------------------
This .sig deliberately left blank...
 
 
 

1. abysmal modem speed

a few weeks ago i was regularly getting connect speeds of 24000
and 28800 with my internal 33.6 modem (one of those former
Online Media jobbies).  then one day for no apparent reason it
went down to 12000, 9600, 7200 and now 4800. very frustrating.
 - i have wasted an embarrassing amount of time floundering about
messing with this setting and that, not really knowing what all those

 - have had BT check the line and increase its "gain" -- no improvement
(although this helped in a previous episode last summer).
 - have swapped telephone lead from another modem -- no better.

here are lines from my Antsuite log showing the start of recent online
sessions (ATW2\V1 in the modem init string produces this report):
    12:08 < CONNECT 57600/V34/LAPM/V42BIS/31200:TX/4800:RX
    22:36 < CONNECT 115200/V34/LAPM/V42BIS/28800:TX/4800:RX
   984:40 < CONNECT 115200/V32/LAPM/V42BIS/4800
  2172:10 < CONNECT 57600/V32/LAPM/V42BIS/4800
   [reboot]
   142:05 < CONNECT 38400/V32/LAPM/V42BIS/4800
   258:16 < CONNECT 38400/V32/LAPM/V42BIS/4800
   851:37 < CONNECT 57600/V34/LAPM/V42BIS/31200:TX/4800:RX

as i understand it, the first figure is the "port" speed.  the OM modem
came with 57600 recommended; i tried cutting it to 38400 to see if
it made any difference; also tried putting it up to 115200.

i don't know what causes V32 instead of V34 sometimes
(and have only a hazy idea of what they mean anyway).

and i take it that the 31200 and 4800 mean transmit and receive rates.
it would be much more useful the other way round: faster receive.
but how to reverse it?

also, the modem frequently fails to connect at all; after 60 seconds
of telephone time i get this line:
  08:42 "No response from modem - retrying"

i'm on a StrongArm RiscPC, RiscOS 4.00, internet module 5.04,
Antsuite 1.32; the modem reports "Acorn V.34 V1.993 ... rev 44BC".

any expertise extremely gratefully received.

--
  --jim nagel
     Computer Shopper magazine UK, freelance

  on a StrongArm xAcorn Risc Machine. British technik. no tax to Gate$.
  immune from MMillenniu worries: online till 2248 AD

   ... kindly warn before sending fat files
   ... no Microsoft attachments (Word, Office, Excel, M$HTML, ...) please
        keep those viri, worms and trojans to yourself

remove ".spamyourself" to reply -- unless you are a spammer

2. http and server-side "with event" Com object question

3. Does Digital TV affect modem speed?

4. Traversing XML DOM using JSP

5. Modem Speed Takes A Dive!

6. Problems with Symantic C++ 6.0

7. Internet Ready Packs and Low Priced U.S. Robotics Modems ( All Speeds)

8. myodbc and C++ problem

9. Modem connection speeds

10. Speed up you modem - maybe

11. ANT's ISDN modem driver SEGSpdDrgn for the HAGENUK SPEED DRAGON DataBox

12. Serial port speed with Vi modem

13. Speed of 20-30 clients accessing a 28.8K modem.....