Path: utzoo!utgpu!watserv1!maytag!xenitec!tirith.ocunix.on.ca!ggk From: ggk@tirith.ocunix.on.ca (Gregory Kritsch) Message-ID: Date: 24 Feb 21 22:11:13 EST Newsgroups: comp.sys.amiga.hardware Subject: Re: Serial Cards In-Reply-To: greg@bronze.ucs.indiana.edu (Gregory R. TRAVIS) References: <1991Feb22.015548.21157@bronze.ucs.indiana.edu> greg@bronze.ucs.indiana.edu (Gregory R. TRAVIS) writes: >I just bought an ASDG dual serial board, which is nice but the performance >is disappointing. It does not seem to perform as well as the internal Amiga >serial port. This is an A2500HD/30 system. I bought it over >the Commodore card because I could not get confirmation that the >Commodore card would drop DTR when the device was closed, which >I absolutely need. As I recall, the board has a small buffer (256 bytes?) only, no processor, and so counts entirely on your motherboard processor to do its magic. The internal serial port has a single byte buffer, but has a fairly high priority interrupt associated with it. >I am not using ASDG's SDB tool (which allows you to use their board >even with exceptionally stupid software which has serial.device >unit 0 hard-wired) and use VLT's device selection requestor. Still, >the ASDG software seems to start up a task called SIOSBX-RA which >runs at very high priority. Setting the priority of this non-CLI >task to a reasonable number allowed ProPage to load in under 15 >seconds but made the error rate on transfers go through the roof >and the comm software gave up. Anyone know why ASDG needs this >task to be running, even when not using the DOS Handlers they >provide (i.e. by opening their version of "serial.device" directly)? The high priority setting is quite reasonable. When the buffer on your serial board fills up, the most important thing to your machine should be transferring the data out of that buffer into main memory, right. If it's not transferred, then it becomes lost, which is a transmission error. It normally won't take that long to transfer, so you probably won't notice it a lot. Unless you're trying to do a download at 19200 baud... Did you happen to use something like xoper, which would report CPU loading and the % of time that the SIOSBX task was active? >So, I guess it loads the system pretty heavily, even for a $300 board. I am >using the latest (ver 1.5) ASDG driver software. Yup. Although I'm a bit suprised at how much its apparently loading your 2500/30. I suppose the bus interface isn't helping much though. >Anyone got timings for the Commodore board under the same situations? >I was NOT using the other ASDG port when I ran these tests. No. But I think (I'm not sure of this) the Commodore board has its own processor, which I assume means that it can get the data into memory essentially by DMA, without worrying the main processor about the transfer. (No, please don't start an argument about whether a DMA serial port is better than a non-DMA serial port - this time it should quite obvious at high speed). -- Gregory Kritsch | University of Waterloo Fido: 1:221/208.11110 [1:163/109.30] | 1B Computer Engineering OCUG: ggk@tirith.ocunix.on.ca |---------------------------- UUCP: ggk@tirith.UUCP | The University doesn't get ...!watmath!xenitec!tirith!ggk | a chance to censor me!