From: Adam Dunkels (adam_at_sics.se)
Date: 2002-04-13 08:08:09
On Saturday 13 April 2002 02.18, you wrote: > > Embedded Ethernet board from Systor Vest AS > > (http://www.embeddedethernet.com/) and a single 74LS139 decoder chip > > mounted on a custom made printed circuit board. > > Which uses the CS8900A > > I've only read the datasheets and app notes a little bit. > > But you can't use interrupts in 8 bit mode, so are you polling? > > (only reason I could see for not being able to use interrupts in 8bit > mode is that, to clear the interupts you have to read the queue, and > that is done in 16 bit mode, but I wonder if you could do your accesses > in eight bit mode, then read the queue to clear the interrupts) Yes, we are polling. Because the interrupts were said to be flaky in 8-bit mode, we didn't even bother connecting the IRQ line from the CS8900a chip to the C64. Interrupt driven use would be advantageous for multitasking systems such as LNG where a task might run for a "long" time (100ms or so) before it is preempted. With interrupts, tasks could be preempted immediately when a packet arrives and the TCP/IP task could be switched in. With event based systems (such as the current uIP implementation), interrupts aren't necessary since tasks cannot be preempted anyway. /adam -- Adam Dunkels <email@example.com> http://www.sics.se/~adam Message was sent through the cbm-hackers mailing list
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