sellgren@snow.Berkeley.EDU (Steve Sellgren) (02/12/91)
I'm trying to filter a/d samples through a mac II, coming in through the modem port. The problem is that I need a data rate faster than the 57.6 Kbaud that Inside Mac says is the fastest. Apparently AppleTalk runs around 230Kbaud, but I hear that external clocking can push the SCC to rates around 4Mbaud (not that an application could keep up with that). Looking at the control codes that are passed to the ROM routines, it seemed plausible that a baud rate of 0 might really be external clocking, but that didn't work... If someone could please clue me in on ways to do faster data transfer, especially externally clocked, I'd really appreciate it. Steve Sellgren University of California, Berkeley
mandel@vax.anes.tulane.edu (Jeff E Mandel MD MS) (02/14/91)
In article <40925@ucbvax.BERKELEY.EDU> sellgren@snow.Berkeley.EDU (Steve Sellgren) writes: > >I'm trying to filter a/d samples through a mac II, coming in through >the modem port. The problem is that I need a data rate faster than >the 57.6 Kbaud that Inside Mac says is the fastest. Apparently AppleTalk >runs around 230Kbaud, but I hear that external clocking can push the SCC >to rates around 4Mbaud (not that an application could keep up with that). >Looking at the control codes that are passed to the ROM routines, it seemed >plausible that a baud rate of 0 might really be external clocking, but that >didn't work... > >If someone could please clue me in on ways to do faster data transfer, >especially externally clocked, I'd really appreciate it. > >Steve Sellgren >University of California, Berkeley > 1) The Zilog Z8030/8530 Product Specification (00-2439-01) claims to support "Two independent, 0 to 2M bit/second, full-duplex channels". Not 4M. 2) External clocking appears to be set from a different SCC register from baud rate. Setting registers on the SCC is not for the weak-hearted. 3) The SCC manual will tell you how to deal with the chip, and if you are really clever, you can probably figure out how make the Mac service the SCC at the rates you need, but the Mac will have trouble functioning as a Mac. 4) What kind of awesome device do you have that can generate serial output at those kind of rates? Or are you just generating a pulse stream with a VCO? Recommendation from someone who has been around this block: Get a Nubus card such as the National Instruments NB-MIO 16 or such. Life is too short to spend it writing serial communications drivers. Jeff E Mandel MD MS Asst Professor of Anesthesiology Tulane Unversity School of Medicine New Orleans, LA