Serial Port Questions

Greetings:

I am running an Amiga 2000 with a GVP accelerator (I believe 040 in this machine) and it has a multi-port serial card as well. The software side is ROM 2.04 and Kickstart 2.1/WB 2.1.

I have been transferring files from my old Pentium 120 PC to the Amiga fine using the built-in 25 pin serial port with NComm 3.06 on the Ami and PCPLUS DOS on the PC. The files seem to transfer fine with this scenario without errors. (The transfers were done with Zmodem).

Recently, I decided to hook the Ami up to my Mac G5 via a USB to Serial Adapter (which has worked flawlessly with many other computers) and the terminal on the Mac is Zterm. I started getting multiple errors (CRC, header too long, etc) and ended up with corrupt files, again using Zmodem on both ends.

Has anyone successfully used a PPC Mac to transfer files to their Amiga? If so, I would love to figure out what setting I could be missing. Also, I seem to recall that there were better serial device files for the Ami, perhaps this is a route to explore as well. It seems to be just a problem from the PPC Mac to the Ami only... though I have not tried my older 68K Mac with this setup. The PC however (which is actually running OS/2) works flawlessly so I am a bit at a loss for what might be happening.

Help is appreciated!

BTW: The goal is to setup this particular A2000 as a BBS using DLG Professional.

Thanks,

Mike

[prowler]

Originally Posted by iainnitro

Greetings:

I am running an Amiga 2000 with a GVP accelerator (I believe 040 in this machine) and it has a multi-port serial card as well. The software side is ROM 2.04 and Kickstart 2.1/WB 2.1.

I have been transferring files from my old Pentium 120 PC to the Amiga fine using the built-in 25 pin serial port with NComm 3.06 on the Ami and PCPLUS DOS on the PC. The files seem to transfer fine with this scenario without errors. (The transfers were done with Zmodem).

Recently, I decided to hook the Ami up to my Mac G5 via a USB to Serial Adapter (which has worked flawlessly with many other computers) and the terminal on the Mac is Zterm. I started getting multiple errors (CRC, header too long, etc) and ended up with corrupt files, again using Zmodem on both ends.

Has anyone successfully used a PPC Mac to transfer files to their Amiga? If so, I would love to figure out what setting I could be missing.

Hi Mike,

Have a look in this thread:

Copying from Mac to Amiga via serial cable

It might give you some ideas...

Thanks Prowler. I am not sure what the take away was going to be after reading your linked post. I have a regular serial cable (PC Style) which is a 9 to 25 pin... this is coupled to a 25 pin null modem adapter which is plugged into the Amiga Serial Port. The other end hooks to my USB to Serial Adapter on the Mac G5.

This in mind, it should be okay for the flow control to be on? It is currently turned on.

Again on the Miggy, it is Ncomm 3.06 for the term program. I have the settings set at 38400 currently then of course N81, but did try cutting the baud to 19200 and had no improvement of the transfers (this was before my original posting). Everything else seems to be setup similarly to the thread you posted.

Again I am not sure if the device file on the Amiga is setup right or not. I know the GVP Serial device exists for the expansion card (multiple serial port card) and I suspect the original Ami driver for the on-mainboard ports is also present, but not sure if there is a better choice.

Thanks again for posting the thread link and I did read it... but it seems that I have actually tried the fixes presented. And I know that the serial cable is good, the null modem adapter is good and the USB to Serial Adapter is good... they work with a bunch of other machines I have such as my Apple IIe and IIgs.

Still a little at a loss on what I could tweak to fix the issue.

[Jope]

Can't be arsed to look at the link, so I'll be my unhelpful self and suggest you look into handshaking.

Many USB rs232 adapters suck at hardware handshaking (RTS/CTS). Try XON/XOFF instead.

[Ed Cruse]

Originally Posted by Jope

Can't be arsed to look at the link, so I'll be my unhelpful self and suggest you look into handshaking.

Many USB rs232 adapters suck at hardware handshaking (RTS/CTS). Try XON/XOFF instead.

With Z modem you shouldn't be using any handshaking, especially not XON/XOFF. XON/XOFF should never be used for binary data, only ascii, because the serial port will detect them but will also eat them. As long as the serial receive buffer is larger then the packet size you don't need or want any flow control.

[Jope]

It just occurred to me that I meant to say flow control, but you understood so it isn't so bad. :-)

Ok, good reasoning behind avoiding XON/XOFF. I always used RTS/CTS back in the day, even with ZModem and didn't have issues with that.

Anyway, I guess it still stands that if you use RTS/CTS with USB to RS232 devices, it might cause you problems.

[Ed Cruse]

Originally Posted by Jope

It just occurred to me that I meant to say flow control, but you understood so it isn't so bad. :-)

Ok, good reasoning behind avoiding XON/XOFF. I always used RTS/CTS back in the day, even with ZModem and didn't have issues with that.

Anyway, I guess it still stands that if you use RTS/CTS with USB to RS232 devices, it might cause you problems.

If receive buffer is somewhat larger then zmodem packets then it shouldn't matter if RTS/CTS is on or off, but flow control of any kind is not needed so shouldn't be used. So yes, turn off RTS/CTS to be safe. My suggestion would be to turn off all flow control and make sure the receive buffer of the receiving computer is larger then the packet size, if not none then make it big.

In case anybody doesn't understand, Zmodem and other error free protocals send a packet and then wait for a response from the receiver to either resend last packet or send next packet. These protocals because of the packets are basically doing their own flow control, therefore they don't need any flow control from the serial port and therefore you shouldn't use any. However for these protocals to work the receive buffer must be at least large enough to hold an entire packet, I usually go for twice or more. When in doubt go for more.

[Jope]

Hmm..

http://www.blast.com/index.php?id=61#ZMODEM

BTW, now that I think about my past life a bit more, the ZModem resends were killing me if I didn't have flow control in place.

[Ed Cruse]

Originally Posted by Jope

Hmm..

http://www.blast.com/index.php?id=61#ZMODEM

BTW, now that I think about my past life a bit more, the ZModem resends were killing me if I didn't have flow control in place.

Hmm. If your serial receive buffer is big enough hardware flow control should never be invoked, if it isn't then it should stop the sender and maybe lock up. My programs tell the serial driver to wait for the whole packet to be received rather then receive one character at a time, this is much faster. However this would hang if hardware flow control actually stopped the sender, so it depends on the program.

If the serial receive buffer is bigger then the Zmodem packet then you don't need any flow control of any kind. Plus hardware flow control slows the serial driver down so it's faster to not use it. For xmodem, ymodem, zmodem, and others, no flow control should be fastest and most reliable way, and always has been for me. The only protocal that I know of that this might not be true is Kermit. I think it sends continuously and deals with bad backets and resends when it gets around to it, not sure though.

[Jope]

If you think about an A500, ks2.04 and 512/512 RAM with a 14.400bps modem connected to the motherboard rs232 port, you're really going to want the flow control. :-)

Perhaps it worked for you back in the day without, but I loved my RTS/CTS.. Calls were expensive in Finland (no free local calls), I preferred a more reliable transfer to constant retransmits..

Having thought about the past and refreshed my memory by reading various docs on the net, I'm keeping my opinion about the positive effect RTS/CTS has on serial transfers (even with ZModem) when you've got slow computers. We'll have to agree to disagree on the general zmodem + flow control subject. :-)

[Ed Cruse]

Originally Posted by Jope

If you think about an A500, ks2.04 and 512/512 RAM with a 14.400bps modem connected to the motherboard rs232 port, you're really going to want the flow control. :-)

Perhaps it worked for you back in the day without, but I loved my RTS/CTS.. Calls were expensive in Finland (no free local calls), I preferred a more reliable transfer to constant retransmits..

Having thought about the past and refreshed my memory by reading various docs on the net, I'm keeping my opinion about the positive effect RTS/CTS has on serial transfers (even with ZModem) when you've got slow computers. We'll have to agree to disagree on the general zmodem + flow control subject. :-)

You are correct in the need for flow control, but xmodem, ymodem, and zmodem are block protocals and as such do there own flow control. The sender sends a block and then stops and doesn't send anymore until receiver replies back with either a send next block or send last block again. As long as serial receive buffer is large enough to hold entire block then you will not have problems. Example, the default Amiga serial buffer size if 4096, this would be no problem with xmodem which uses 128 byte blocks. Zmodem is probably much larger, but as long as the buffer size is larger then the block size then it will work no matter how slow the computer is. Hardware flow control would be used if you are sending a continous binary data steam and not using a block protocal. Xon/Xoff or hardware flow control would be used for continous ascii data stream transfers.

I remember doing 300 and 1200 baud transfers using long distance and it was expensive to download anything big, but I had very few resends on a A1000 using xmodem and no serial port flow control.

OK, I guess we will agree to disagree.