Re: TFE - C64 Ethernet Cartridge

From: Adam Dunkels (
Date: 2002-04-13 08:08:09

  • Next message: Adam Dunkels: "Re: TFE - C64 Ethernet Cartridge"
    On Saturday 13 April 2002 02.18, you wrote:
    > > Embedded Ethernet board from Systor Vest AS
    > > ( 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 Dunkels <>
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