Re: C64 cluster

From: Jim Brain (
Date: 2007-11-07 01:29:51

Ethan Dicks wrote:
> On 11/7/07, Jim Brain <> wrote:
>> My thought was the cost of finding the connectors.  For a user port, you
>> could rob an old modem (though I generally discourage hacking antique
>> CBM items, I can make an exception for any 1660 variant).  The cassette
>> port is a bit harder to find, though game carts exist in the plenty.  As
>> well, a small PCB with just the card edge is a mere buck to produce and
>> sell for those who want a nice looking setup.
> I don't recall either the 6-pin  (cassette port, single-sided) or the
> 24-pin (user port, double-sided) connectors being particularly
> difficult to find.  They aren't as inexpensive as, say, a DE9 or DB25,
> but they are still being made, AFAIK.
> The usual places I start with are Jameco, Digikey, and Mouser.  The
> connectors are ordinary 0.154" spacing edge connectors.
DigiKey has them in stock, it's just the minimums from places like 
DigiKey that thwart many a project.  I suppose that if you were building 
this, you'd buy a handful of them and hit the minimums.

To carry the consensus feeling forward, how would folks use the user 
port for networking?  I know Centipede 128 used a simple 1-1 connection 
to hook two machines together, but I've not seen other uses.

Hooking all 8 data lines across 64 machines will not work due to fanout, 
so you have the following options:

    * Use SP1/CNT1 as an input, and SP2/CNT2 as an output.  Transfers
      are limited to CLK/32 bytes/sec or 31K theoretical.
          o This allows a 4 wire data connection, though one might want
            to add an ATN wire to denote commands on input and output.
    * Use 4 bits of PB for inputs, and 4 for outputs.
          o More bits, but CLK/8 speed max.

Any other ideas?

Jim Brain, Brain Innovations                                      (X) 
Dabbling in WWW, Embedded Systems, Old CBM computers, and Good Times! 

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