A   standard   X(E)1541  cable  won't work with _this_ driver. In
fact, there will probably never be a multitasking OS which  works
with  one   of  these, that's why we call it XM1541, M for Multi­
tasking. Anyway, if you have a XE1541, the necessary modification
is simple:

         Exchange pins 5 & 6 on the Commodore DIN plug
         ---------------------------------------------

The ACK line is the only line on a PC parallel port that can gen­
erate a hardware interrupt. This way, we get  an  interrupt  when
the  device  releases the DATA line to signal "ready to receive".
Without an interrupt, you would have  to  poll  for  this  signal
about  every  100us,  which  is inacceptable for any multitasking
system.

Be sure to have your parallel port configured to use an IRQ, usu­
ally 7 or 5, but both are often also used by soundcards.

(ASCII art taken from the StarCommander README :))


The PC parallel plug (male DB-25 connector):

        PaperEnd   Busy
    SelectIn   |   |   Ack        Data 7 - Data 0       Strobe
           |   |   |   |   +-------------+-------------+   |
           V   V   V   V   |                           |   V
        +------------------------------------------------------+
        | 13  12  11  10   9   8   7   6   5   4   3   2   1   |
        |  o   o   o   o   o   o   o   o   o   o   o   o   o   |
        +-+                                                  +-+
          |  o   o   o   o   o   o   o   o   o   o   o   o   |
          | 25  24  23  22  21  20  19  18  17  16  15  14   |
          +--------------------------------------------------+
             |                           |   ^   ^   ^   ^
             +-------------+-------------+   |   |   |   |
                        Ground          Select   |   |   AutoFeed
                                              Init   Error

The Commodore drive serial bus plug (male 6-pin DIN connector):

                                 Reset
                                   |
                                   V
                          +-------+ +-------+
                        +-+       +-+       +-+
                        |     5         1     |
               Data --> |     o    6    o     | <-- SrqIn
                        |          o          |
                        |     4         2     |
                Clk --> |     o    3    o     | <-- Gnd
                        |          o          |
                        +-+                 +-+
                          +-----------------+
                                   ^
                                   |
                                  Atn


This is the XE1541 cable (won't work with this driver):

    CBM drive serial port   PC parallel port

        2  Gnd ---------- 18-25  Ground
        3  Atn --------+---- 13  SelectIn
                       +->|-- 1  Strobe
        4  Clk --------+---- 12  PaperEnd
                       +->|- 14  AutoFeed
        5  Data -------+---- 11  Busy
                       +->|- 17  SelectIn
        6  Reset ------+---- 10  Ack
                       +->|- 16  Init


This is the XM1541 (pins 5 & 6 on the CBM end exchanged)

    CBM drive serial port   PC parallel port

        2  Gnd ---------- 18-25  Ground
        3  Atn --------+---- 13  SelectIn
                       +->|-- 1  Strobe
        4  Clk --------+---- 12  PaperEnd
                       +->|- 14  AutoFeed
        6  Reset ------+---- 11  Busy	
                       +->|- 17  SelectIn
        5  Data -------+---- 10  Ack
                       +->|- 16  Init


For more information about the different cables, please check out
the StarCommander homepage on <http://sta.c64.org/sc.html>


Have fun,
Michael Klein <nip@c64.org>