Re: Cisco AX.25 support (was: Gracilis card question)

["Matti E. Aarnio [OH1MQK]" <mea@mea.cc.utu.fi>]

> > But how many 4Mbps interfaces exist for the 486, and how many of them
> > could it support? Would you be interested in the project if you could
> > have T1 or better over the radio? (There is local interest in such a
> > product.)
>
> Well the PI/2 can allegedly do 2Mb/sec, and I'd put a bet on it being
> cheaper to design and build a fast I/O driven 4Mb/second board based on
> a 68302 than to buy a Cisco. [Im not saying you dont get good things from
> a Cisco, just its the wrong approach]

        Actually I don't believe you can push more than 2Mbps (aggregated)
        thru 68302's serial units.

        I had a design with MC145488 (DDLC), however those serial chips
        (HDLC only) were discontinued.  It was able to push 2Mbps per
        channel.

        High-speed (Mbps) serial chips exist from  Rockwell (cisco uses
        them, but with external DMA..), Zilog, Motorola, Intel, AMD...

        Some of them come to my mind (I have datas):
        - i82586, i82596 (Ethernet AND HDLC)            Mono channel, costly
        - MC68360, MC68EN360                            Quad channel, costly
        - Z16C32 (aka Z16C320, markings appear to vary) Mono channel, cheap

        Those all have internal DMA controllers, so a board with internal
        buffer, or (heaven forbid!) busmaster DMA are possible..
        I do like the internal buffer style :-)

        You may be able to rework an ethernet board with i82586 into
        a mono-channel FDX HDLC interface with speeds up to 20Mbps.

> With an ISA bus 4Mb/sec boards are going to be a problem at about 2 or 3
> from gut feeling, with PCI it won't be an issue.

        Right.  Do you have any good references on building PCI boards ?
        Must I call Intel ?

        /Matti Aarnio   <mea@utu.fi>    OH1MQK