De600.xif

From SpareMiNT Wiki

Some notes on the DE600 driver.

[edit] Hardware

You need the TUW hardware (HPGL layout and hardware description available from fortec.tuwien.ac.at by anonymous ftp) to connect the DE600 to the cartridge port.

The driver is interrupt driven and does *not* poll for input packets during the VBL interrupt (like the original tuw-tcp driver), so you MUST MUST MUST connect the interrupt wire to pin 11 (BUSY) of your centronics port. Otherwise it will not work!

[edit] Usage

Setting up the driver is rather simple: MintNet must be installed and copy de600.xif to c:/mint/ or c:/multitos/ and reboot. Then issue the following two commands:

ifconfig en0 addr 141.2.1.99
route add 141.2.1.0 en0

and all should work fine. Of course 141.2.1.99 must be replaced with your local IP address, 141.2.1.0 with the network address of your local IP address (ie host portion set to zero) and en0 with the interface name the DE600 driver shows in its startup message at boot time.

[edit] Performance

First some speed rates on a 16MHz ST (on an otherwise idle network):

ftp send: ~88 k/sec (ncftp 1.7.5 -> wu-ftpd 2.0)

ftp recv: ~85 k/sec (ncftp 1.7.5 <- wu-ftpd 2.0)

tcp send: ~90 k/sec (tcpcl -> tcpsv)

tcp recv: ~90 k/sec (tcpsv <- tcpcl)

nfs read: ~50 k/sec (nfs 0.51: rsize=1200, wsize=2048)

nfs write: ~45 k/sec (nfs 0.51: rsize=1200, wsize=2048)

Receiving data on a DE600 is very critical because it has only two receive buffers and reading a packet from the adapter is slower than packets arrive from the net. So to achieve any receive performace the number of packets that are sent to the de600 in fast succession must be limited in some way. For TCP this is easy, the adapter tells the TCP to limit its receive window to 1500 bytes. But the trouble starts if you have multiple TCP connections over the de600 in which case limiting the receive window doesn't work...

Problems occur for applications using UDP (like NFS). They often receive packets larger than the interface MTU (1500 bytes), so they get fragmented by IP into many packets and flood de600's receive buffers. When you mount a filesystem you must therefor tell NFS to limit the receive packet size to MTU - 300 bytes (the 300 bytes are used for NFS protcol headers...), ie you would say:

mount -o rsize=1200 remote:/dir /nfs/dir

[edit] Extra notes

The driver was written and tested on a 16MHz ST, so if you run it on substantially faster machines, there may occure timing problems.