NOTE: Jokes about dialup connections and questions about "why would you still use dialup in 2009" are not relevant to this thread. Keep the snarky comments to yourselves, please.


I started a thread here about problems I was having connecting to the Internet using dialup, that I marked as "solved" because I am now able to connect.

However, the problems are not really solved, I just found a workaround that I can use (changed modems). There are still some serious problems with the serial driver on the Sam and with the dialer program. I'll limit this post to the bugs I suspect are in ppc440ep_serial.device.


1. The serial port driver doesn't raise Data Terminal Ready (DTR). It appears as though some modems cannot be used with the Sam and OS4.1 because they require a DTR signal from the computer. My two US Robotic modems have switches on them that allow me to get around this problem, but I suspect that this is also a problem with GVC modems and they don't have a switch for this.

2. There is a problem with sending data through the serial port. It seems as though it is not possible to use serial port speeds higher than about 30kbps and also be able to upload files and send sizeable e-mails successfully. If I set my serial port speed to 28,800bps my e-mails go out OK, but at 38,400bps YAM has to do a lot of retries. At 115,200bps I can't send e-mails at all or upload files, unless they are very small (less than 2K?). Yet I can set my serial port to 115,200bps and connect with my 28,800bps modem and surf and download without much trouble.

Last edited by robo-ant on 17-May-2009 at 09:02 AM.

@robo-ant
Apparently the SAM serial device has inherited the problems of OS4Final+ a1serial.device on the µA1 (& A1??). The symptoms are the exactly the same. On the µA1 the problem can be solved by reverting to earlier releases of a1serial.device or using a 28,800 modem as you have done. If you have a PC, maybe some serial breakout software like that mentioned at: http://www.taltechnologies.com/news/breakout.htm could be of some use in diagnosing the problem. I only have one computer (µA1) right now or I would try it myself. I have a SAM Flex on order and am looking for a 28.8 modem but haven't found one yet. When I get my SAM I will immediately try my derial dialup and let you know if I have any problems.

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X1000 with 2GB memory & OS4.1FE

@robo-ant

Quote:

2. There is a problem with sending data through the serial port. It seems as though it is not possible to use serial port speeds higher than about 30kbps and also be able to upload files and send sizeable e-mails successfully. If I set my serial port speed to 28,800bps my e-mails go out OK, but at 38,400bps YAM has to do a lot of retries. At 115,200bps I can't send e-mails at all or upload files, unless they are very small (less than 2K?). Yet I can set my serial port to 115,200bps and connect with my 28,800bps modem and surf and download without much trouble.

Sounds to me like the serial port is sending data to the modem faster that themodem can receive it / pass it on. Some kind of buffer overflow issue?

But what is there to be gained by setting the serial port to a higher rate than the connection anyway?

I can see where the problem might arise though with a 56k modem as the up speed is less than the download speed.

It's ages since I've used dialup. I do rememebr I never had issues, unfortunatly I can't rememebr what modem I used that worked!

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BroadBlues On Blues BroadBlues On Amiga Walker Broad

@broadblues
Quote:

Sounds to me like the serial port is sending data to the modem faster that themodem can receive it / pass it on. Some kind of buffer overflow issue?But what is there to be gained by setting the serial port to a higher rate than the connection anyway?

Most modern modems recommend sending the data to the modem as fast as possible. Some of the modem speed is achieved through compression and the quicker the modem gets the data from the computer the sooner it can compress and send it. Modern modems use hardware flow control so when the modem buffer fills it signals the serial port to stop sending. This all worked for 56k dialup users until OS4 Final. On my µA1, I am able to use the OS4 Pre4 serial device with no problems (no matter what the serial port speed setting is). Unfortunately, SAM users have no earlier version of the serial driver to revert to.

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X1000 with 2GB memory & OS4.1FE

@broadblues

Quote:

Sounds to me like the serial port is sending data to the modem faster that themodem can receive it / pass it on. Some kind of buffer overflow issue?

Yes, but the modem is supposed to signal that its receive buffer is filling up, and the computer connected to it is supposed to notice the signal. Question is where this signalling goes wrong.

Does the modem signal anything (this could be an initialization command issue)? Does the computer see the modem's signal (this could be a cable issue)? Does the driver notice and report the modem's signal (this could be a software issue)?

@robo-ant
My SAM Flex system just shipped so I'll let you know how dialup/serial connection is working on my SAM. I've been looking for a 28,800 modem just in case I have the same problem. Unfortunately, the modems seem to be listed by the protocols they support rather than max speed. My 56k modems are v.92/v.44. Can you tell me what protocols your 28,800 modem uses??

Last edited by Xenic on 18-May-2009 at 03:58 PM.

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X1000 with 2GB memory & OS4.1FE

@robo-ant
You think you got problems; my SAM Flex arrived and it won't get me online at all. I'm using the exact same settings and modem that work on my µA1. The modem makes a connection (usually 28,800) but Dialer can login to my ISP. It just times out and throws up an error message "Reaource allocation failure ...". If I leave the modem on when I turn on or reset the computer UBoot seems to access the modem and causes it to start making connection sounds. If I wait until the computer has booted to turn on the modem, the system sometimes freezes (locks up). Does anyone have any suggestions??

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X1000 with 2GB memory & OS4.1FE

@Xenic

One problem here I see with the Sam is only one serial port unless you somehow expand it to get the others mentioned in the specs. When I used dial up with my A1 I had the same problem of Uboot "talking" to my modem, though not as severe as making crank phone calls, at best it might have confused it. I had the luxury of another serial port right there unused by Uboot which I used to solve that problem. So right now perhaps leaving the modem switched off until you connect might be one solution. But if this causes a freeze that is a bigger problem.

At this stage I would run Snoopy and whatever else you can to track the problem down.

I take it the A1 serial driver would not work on the Sam as it is embedded in the CPU? So probably not using the same "off the PCI bus" type arrangement even if the same chipset or programming were the same.

@Hypex
Quote:

At this stage I would run Snoopy and whatever else you can to track the problem down.

I might give that a try but I don't think the problem is in the system software. Someone just told me in an Amigans.net forum that the SAM Flex has a 4 wire serial port with no DTR/CTR lines. I don't remember reading that in the specs. If I can't find a way to get it working without DTR/CTR then I will have a very expensive paperweight for my desk.

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X1000 with 2GB memory & OS4.1FE

@Xenic

Quote:

I might give that a try but I don't think the problem is in the system software. Someone just told me in an Amigans.net forum that the SAM Flex has a 4 wire serial port with no DTR/CTR lines. I don't remember reading that in the specs. If I can't find a way to get it working without DTR/CTR then I will have a very expensive paperweight for my desk.

Then that is not good, but it explains a lot. IIRC those lines and and hardware handshaking are needed for 56,000 bps. Without that the Sam is not much better than the serial port on an Amiga! One thing you could try is setting the UBoot serial speed to a lower one like 9,600 bps. Or what your modem is set as.

I don't think the Workbench Serial settings will affect it!

@Hypex
Quote:

Then that is not good, but it explains a lot. IIRC those lines and and hardware handshaking are needed for 56,000 bps. Without that the Sam is not much better than the serial port on an Amiga!

I now have a half-assed solution and you're right; I have to use the kind of settings needed for the builtin serial port in a 15 year old classic Amiga! The hardware handshake doesn't appear to work with either of my modems. I now have one modem working using XON/XOFF and a serial to modem speed of 38,400. Even my old GVP serial card in my A4000 could use 115,200 serial to modem speed with hardware handshaking. I'm a litle ####ed off to say the least.

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X1000 with 2GB memory & OS4.1FE

@Xenic

But XON/XOFF doesn't limit your transmission or reception speed: if the modem can only get up to 38k4 baud, then that's the limit, not what the port can deliver.

_________________
cheers
tony

Hyperion Support Forum: http://forum.hyperion-entertainment.biz/index.php

@tonyw
Quote:

But XON/XOFF doesn't limit your transmission or reception speed: if the modem can only get up to 38k4 baud, then that's the limit, not what the port can deliver.

It's not quite that simple. There is a certain amount of processing overhead involved in sending/receiving data. If the DTE speed (serial port to modem) is the same as the modem connection speed then the serial.device must constantly be active sending/receiving data and hogging CPU time. If the DTE speed is significantly higher than the connection speed then the serial.device can grab data faster than it's coming into the modem; freeing the CPU for further incoming/outgoing data processing and for other tasks on the system. All my modem manuals recommend setting the DTE speed to at least twice the modem speed for accurate results and system stability. XON/XOFF was invented for 1200 baud modem connections. Hardware handshaking has been the standard since 9600/14,400 baud modems were introduced and Internet access was commonplace. Why do you think there were so many different serial I/O cards made for classic Amigas? So people could use hardware handshaking for the fastest possible serial I/O and lowest CPU load. At this point the SAM Flex serial port appears to have about the capability of an A500 Amiga using the builtin serial port.

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X1000 with 2GB memory & OS4.1FE

@Xenic

If the modem is limiting the bit-rate, then the CPU to modem connection's speed doesn't affect the CPU time used. This is because the serial port has a buffer that is cleared periodically. An interrupt is triggered when the buffer reaches a certain fill level, which tells the CPU to read it. As such, if 28kbps are being transferred, then the same number of instructions are used per second regardless of whether these 28 KiB are transferred at 28 kbps, or 115.s kbps.

Hans

_________________
http://hdrlab.org.nz/ - Amiga OS 4 projects, programming articles and more. Home of the RadeonHD driver for Amiga OS 4.x project.
https://keasigmadelta.com/ - More of my work.

@Hans
I don't know enough to argue your point but there must be a reason why serial ports and modems were switched to hardware flow control a long time ago. I can only tell you that sending data through my modem with my SAM Flex is painfully slower than it was with my A4000/GVP I/O card using the same modem. It's also noticably slower than my µA1.
Right now I have more serious problems. Once a day or more the video output from my SAM goes off and I have to reboot. If just happened 15 minutes ago while I was reading an email with YAM. This time the keyboard light was still on so I think the computer was still functioning. Since I see you work on Radeon drivers, I'm wondering if others have reported this problem. Is there a way to restart the video output without rebooting?

_________________
X1000 with 2GB memory & OS4.1FE

@Xenic

Quote:

Xenic wrote: @Hans I don't know enough to argue your point but there must be a reason why serial ports and modems were switched to hardware flow control a long time ago. I can only tell you that sending data through my modem with my SAM Flex is painfully slower than it was with my A4000/GVP I/O card using the same modem. It's also noticably slower than my µA1. Right now I have more serious problems. Once a day or more the video output from my SAM goes off and I have to reboot. If just happened 15 minutes ago while I was reading an email with YAM. This time the keyboard light was still on so I think the computer was still functioning. Since I see you work on Radeon drivers, I'm wondering if others have reported this problem. Is there a way to restart the video output without rebooting?

Hardware flow control is more efficient, there's no doubt about it. As for the Radeon drivers, I'm not working on the ATIradeon.chip drivers that everyone is using. My RadeonHD.chip driver is completely independent, and supports a different set of graphics cards. I did notice someone else on amigans.net mentioning that he had his monitor switch off. See the thread here.

Hans

Last edited by Hans on 25-May-2009 at 05:44 AM.

_________________
http://hdrlab.org.nz/ - Amiga OS 4 projects, programming articles and more. Home of the RadeonHD driver for Amiga OS 4.x project.
https://keasigmadelta.com/ - More of my work.

@Xenic

Quote:

...there must be a reason why serial ports and modems were switched to hardware flow control a long time ago...

I don't think they were "switched". I remember having the choice of RTS/CTS or XON/XOFF handshaking back around 1970, when modems were 300 baud if you were lucky and 1200 baud was only possible in half duplex mode! The disadvantage of XON/XOFF handshaking was then (and still is) that to send a "Stop!!" message across to the other end of the channel, always adds the overhead of sending and receiving a character (one to two whole character times). At high transmission speeds, the sender at the other end might have sent several more unwanted characters before he hears your XOFF and shuts up.
If you used RTS/CTS, on the other hand, you only had to send a change in level, which is much faster.

That was a problem in the early 1970s before UARTs and USARTs with built-in FIFOs became available. Nowadays the problem is trivial and dealt with in the hardware. XON/XOFF are still used at a higher level.

To get back to your problem though, we still don't know the cause - as Olaf said, it might be any of several causes, not the fault of the Sam or the driver at all.

I/we/someone needs to do some proper tests on the Sam/serial.device combination to ascertain if there really is a problem, and if so, how to fix it. If there is a software (driver) problem, it is likely to be in the A1 version as well.

_________________
cheers
tony

Hyperion Support Forum: http://forum.hyperion-entertainment.biz/index.php

@Xenic

Another solution is to use a router to dial up! I have seen a NettComm that was a router with a modem conbined. It allowed four computers to be connected via ethernet and when it got the command would dial out and connect to the internet. This would solve your serial problems and allow you to have more than one machine online! I don't know if they can still be found but not long ago I found this to be a very useful device.

I saw one at my Amiga club. And we even used it to share internet by hooking it into the phone line. But four people using a 56k connection was a challenge!

Pitty it seems if modern ADSL routers don't have the backwards ability to dial up. Surey the hardware is there.

@anyone with serial port connectable Wacom tablet & SAM

Does that combination work?

(I'll try it one day...)

_________________
- KimmoK
// For freedom, for honor, for AMIGA
//
// Thing that I should find more time for: CC64 - 64bit Community Computer?

@Hypex

Quote:

Another solution is to use a router to dial up!

Interesting. I was not aware of these devices. It seems they are called "LAN Modems", and there is an example here:

http://www.amazon.com/3Com-3C886-OfficeConnect-56K-Modem/dp/B00000JBAC

Not exactly cheap but it might solve someone's problems.