flank@ccwf.cc.utexas.edu (Brett Jacobson) (01/06/91)
After looking at a NeXTStation (I am intent on purchasing one REAL SOON NOW.) I came to the conclusion that the serial port problem was MAJOR, however it is pretty easy to solve. The solution is a serial port system based on the SCSI standard. I have used several such system on a SPARCStation 1+, and they work quite well. By doing this, and implementing a driver for the computer, you should be able to drive 8 serial ports at 115Kbps quite easily without putting too much load on the SCSI port. This means you would need to packetize all transmissions (everybody heard of X.25?), which might cause a little jerkyness depending on how large the packet is, and how long you waited to send something that didn't reach a full packet in size. By doing this, you should be able to support the FULL RS-232C standard, using 25pin ports (or maybe RJ-45 for density), with FULL hardware flow-control. If you are interested in this (I am looking at the design right now with a friend from CalTech), you might want to grab the following data sheets from AMD. (These are SCSI controllers): Pub Number Description 10216 Z85C30 Enhanced Serial Communications Controller 08289 Am5380/Am53C80N SCSI Interface Controller 11853 Am33C93A Enhanced SCSI-Bus Interface Controller With a little luck I should be able to get this thing running. Chris Petrilli petrilli@dogface.UUCP (or this account which will get forwarded to me).