Help with Amiga 500 and TF536 lockups

[insanity213]

Hey everyone, I could use some help trying to figure out why my system keeps locking up.

Hardware:
Amiga 500 Rev 5
Escom Kickstart 3.1 ROM
TF536 / 030 / 64MB ram
8 Gig CF card / IDE - CF adapter
A501 trapdoor memory
A520 Video adapter
External floppy
Internal Gotek floppy

Problem:
When downloading a file larger than a few hundred KB directly to the CF card, the system will hard lock within a few minutes. No mouse movement, no guru errors, no flashing lights. The system just locks. I am using MiamiDX as the TCP/IP stack and connected PPP to a Raspberry Pi via the serial port. The RPi has IP routing enabled and is running pppd. I've tried downloading via FTP from a server on my LAN and HTTP from the Internet.

I can download to the ramdisk without a problem and then copy the files over to the CF.
I can run large pings saturating the serial port at 115200 for hours without a problem.
Long telnet sessions aren't a problem. Ran a 'show tech' on a Cisco router, no problems or text corruption.
I can use Amiga explorer to write large files directly to the CF card at up to 115200 baud.
Baud rate doesn't seem to matter, I've tried 9600, 19200, 38400, 57600 and 115200.
I've disconnected the A501, A520 and both floppys.
I've swapped the odd/even CIAs.

The problem seems to only happen when using a TCP protocol and writing direct to the CF card.

The only other idea I've got is that the ROM hack for the A500 rev 5 has known stability problems in some cases. People have added resistor packs to the ROM chip to fix this problem. I ordered a Kickstart socket with the resistor packs for the rev 5 motherboard hoping that it might help.

Any other ideas for things to try? I wish it at least puked an error at me, the hard freeze with no explanation is frustrating!

Thanks!

[Tomswork]

Is it tcp or udp downloads the packet size very from 8 byte udp to 60byte maximum with tcp. Tcp has more traffic overhead and large packets can overflow buffers causing lots of retry and lockups. If you can adjust the tcp packet size down to 20byte and try again

Tom

[insanity213]

Hey, thanks for the fast reply Tom. Are you talking about layer 2 max transmission unit (MTU) on the serial port config? Or is there a setting somewhere for actual layer 3 TCP packet size?

[terriblefire]

Immediately I suspect the max transfer

[Tomswork]

I'm not sure we're in the amiga setting this would be but I would think the layer 2. Also it could be the speed setting just causing trouble.

Tom

[insanity213]

MTU was at 1k, I dropped it to 256 and had the same problem. Dropping to 64 seemed to stabilize things. I was able to download for about 40 minutes straight.

Now I'm curious why the contention between serial port overhead and IDE writes? I'm not very familiar with the CPU architecture in the Amigas, I guess they share a CPU interrupt or something? I wonder how much more performance I'd get with one of those parallel port network interfaces.

Thanks guys, much appreciated!