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This file comes with the Star Commander and explains the various cable types
that the Star Commander supports. VC1541 only supports the X1541 and the
XE1541 cable.
For more information about the Star Commander point your webbrowser to:
http://ludens.elte.hu/~sta/sc.html
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  THE X1541 INTERFACES:

  Here is the description of the X1541 interfaces, with which you can  connect
a Commodore drive to your PC to use with the Commander.

  The mode of your parallel port is  a vital  feature  that  determines  which
cables you can use with your machine so try to find out all the modes of  your
parallel port. Older I/O and parallel port cards only have the  unidirectional
SPP mode, most Pentium and newer 486  motherboards  have  integrated  parallel
ports and allow you to set the port mode in the BIOS  setup,  with  the  usual
choices of SPP, EPP and ECP.

  You can convert unidirectional SPP parallel port cards into a  bidirectional
PS/2 port by disconnecting pin 1 of the data latch  74LS374  from  ground  and
connecting it to one of the output pins on the control latch 74LS174. This pin
can be any of pins 2, 5, 7, 10, 12 or 15 and must  not  be  connected  to  any
other chip on the board. The corresponding input pin (3, 4, 6, 11, 13  or  14)
must be connected to bit 5 of the data bus. If this is not the  case  on  your
card then you can access this bit from the data latch. Find out which  one  of
its output pins (2, 5, 6, 9, 12, 15, 16 or 19) is connected to pin  7  of  the
parallel port connector and get bit 5 from the corresponding input pin (3,  4,
7, 8, 13, 14, 17 or 18).

  It's possible that, when changing the mode of the integrated  parallel  port
in your BIOS setup, you won't find the necessary modes as they are  called  in
this documentation. Some BIOS setups have different names for the port  modes:
Compatible, Normal and Standard usually refer to SPP, Extended  possibly means
PS/2 or EPP and Enhanced stands for EPP or ECP. Please, note that the EPP mode
cannot be reliably detected by SCSETUP on some machines: PS/2 is reported even
if the port is not really in  PS/2  mode.  Use  PS/2,  if  available,  or  ECP
instead.

  The advices below, telling you which cables to use  with  a  given  parallel
port mode and vice versa, are based  on  the  fact  that  most  SPP  and  PS/2
parallel ports support the X1541 cable and most EPP  and  ECP  parallel  ports
don't. However, because of the lack of strict standards, there are  exceptions
to these rules. There exist SPP and PS/2 parallel ports that don't support the
X1541 cable and it's also possible that certain EPP and ECP parallel ports  do
support it. You have to determine the true capabilities of your parallel  port
before choosing the cables to use.

  If you have a unidirectional SPP parallel port then you can  use  the  X1541
cable and, optionally, the XH1541 hybrid cable, for the highest speed possible
on SPP ports. If you have a bidirectional PS/2 parallel port then you can  use
any of the cables but, for maximum speed, you're  advised  to  use  the  X1541
cable and the XP1541 parallel cable together. Unfortunately, since  the  X1541
cable doesn't work with most parallel ports in EPP and ECP mode, you will have
to configure them to SPP mode with the BIOS setup program or with jumpers.  If
the Commander still doesn't work then you have two possibilities:  you  either
use the XE1541 cable, a substitute for the X1541 cable,  or  buy  a  secondary
parallel port card, plug the X1541 cable to it and optionally use  the  XP1541
parallel cable on the EPP or ECP port.

  The X1541 interface is the easiest of all, you only need to connect  certain
pins of the serial port of the Commodore drive and pins of the  parallel  port
of the PC. You need some plugs, some wires  and  some  soldering  skills.  The
XE1541 interface is not much harder, it only needs some additional diodes. The
XH1541 and XP1541 interfaces are a lot harder to build because you need to  do
some modifications inside the Commodore drive. If you're  not  experienced  at
soldering then don't even think about doing them yourself.  In  addition,  the
XH1541 interface also needs some diodes.

  The following tables may help you to decide which  cables  suit  your  needs
best. Depending on your parallel port hardware, your soldering skills and your
patience, you may choose the cables that will work best for you.

  This table is a compatibility chart between different  parallel  port  modes
and different interfaces:

                +---------------+---------+---------+---------+
                | Compatibility |   SPP   |  PS/2   | EPP/ECP |
                +---------------+---------+---------+---------+
                |     X1541     |   yes   |   yes   |   no    |
                +---------------+---------+---------+---------+
                |    XE1541     |   yes   |   yes   |   yes   |
                +---------------+---------+---------+---------+
                |    XH1541     |   yes   |   yes   |   yes   |
                +---------------+---------+---------+---------+
                |    XP1541     |   no    |   yes   |   yes   |
                +---------------+---------+---------+---------+

  This table shows the ways to achieve different speeds on a  single  parallel
ports in different modes:

            +-----------------+-----------+-----------+-----------+
            |   Single port   |    SPP    |   PS/2    |  EPP/ECP  |
            +-----------------+-----------+-----------+-----------+
            |  Minimum speed  |   X1541   |   X1541   |  XE1541   |
            |                 |    (1)    |    (1)    |    (2)    |
            +-----------------+-----------+-----------+-----------+
            |  Medium speed   |  X1541+   |  X1541+   |           |
            |                 |  XH1541   |  XH1541   |           |
            |                 |           |    (1)    |           |
            +-----------------+-----------+-----------+-----------+
            |  Maximum speed  |           |  X1541+   |  XE1541+  |
            |                 |           |  XP1541   |  XP1541   |
            |                 |           |           |    (2)    |
            +-----------------+-----------+-----------+-----------+

  Notes:
    (1) This is not the maximum performance for your parallel  port,  you  may
        want to use another cable configuration.

  These tables show the ways to achieve different speeds on two parallel ports
of different modes. The first cable refers to the primary parallel port, whose
mode is indicated by the table title, and the second refers to  the  secondary
parallel port, whose mode is indicated by the column  title.  Note  that  when
you're advised to swap your parallel ports then it's meant  to  be  a  logical
swap, not a physical one:

          +---------------------+-----------+-----------+-----------+
          |     Two ports,      |    SPP    |   PS/2    |  EPP/ECP  |
          |   primary is SPP    |           |           |           |
          +---------------------+-----------+-----------+-----------+
          |    Minimum speed    |   X1541   |   X1541   |   X1541   |
          |                     |   (1,2)   |  (1,2,3)  |   (1,2)   |
          +---------------------+-----------+-----------+-----------+
          |    Medium speed     |  X1541+   |  X1541+   |  X1541+   |
          |                     |  XH1541   |  XH1541   |  XH1541   |
          |                     |    (2)    |  (1,2,3)  |   (1,2)   |
          +---------------------+-----------+-----------+-----------+
          |    Maximum speed    |           |  X1541 +  |  X1541+   |
          |                     |           |  XP1541   |  XP1541   |
          +---------------------+-----------+-----------+-----------+

  Notes:
    (1) This is not the maximum performance for your parallel ports,  you  may
        want to use another cable configuration.
    (2) You don't need two parallel ports for this  cable  configuration,  you
        can hook the indicated cables up to the primary parallel port.
    (3) This is not the maximum performance for your parallel ports. Swap your
        parallel ports and try again.

          +---------------------+-----------+-----------+-----------+
          |     Two ports,      |    SPP    |   PS/2    |  EPP/ECP  |
          |   primary is PS/2   |           |           |           |
          +---------------------+-----------+-----------+-----------+
          |    Minimum speed    |   X1541   |   X1541   |   X1541   |
          |                     |   (1,2)   |   (1,2)   |   (1,2)   |
          +---------------------+-----------+-----------+-----------+
          |    Medium speed     |  X1541+   |  X1541+   |  X1541+   |
          |                     |  XH1541   |  XH1541   |  XH1541   |
          |                     |   (1,2)   |   (1,2)   |   (1,2)   |
          +---------------------+-----------+-----------+-----------+
          |    Maximum speed    |  X1541+   |  X1541 +  |  X1541+   |
          |                     |  XP1541   |  XP1541   |  XP1541   |
          |                     |    (2)    |    (2)    |    (2)    |
          +---------------------+-----------+-----------+-----------+

  Notes:
    (1) This is not the maximum performance for your parallel ports,  you  may
        want to use another cable configuration.
    (2) You don't need two parallel ports for this  cable  configuration,  you
        can hook the indicated cables up to the primary parallel port.

          +---------------------+-----------+-----------+-----------+
          |     Two ports,      |    SPP    |   PS/2    |  EPP/ECP  |
          | primary is EPP/ECP  |           |           |           |
          +---------------------+-----------+-----------+-----------+
          |    Minimum speed    |    (1)    |    (1)    |  XE1541   |
          |                     |           |           |   (2,3)   |
          +---------------------+-----------+-----------+-----------+
          |    Medium speed     |    (1)    |    (1)    |  XE1541+  |
          |                     |           |           |  XH1541   |
          |                     |           |           |    (3)    |
          +---------------------+-----------+-----------+-----------+
          |    Maximum speed    |    (1)    |    (1)    |  XE1541+  |
          |                     |           |           |  XP1541   |
          |                     |           |           |   (2,3)   |
          +---------------------+-----------+-----------+-----------+

  Notes:
    (1) You shouldn't have an EPP/ECP parallel port as your primary port. Swap
        your parallel ports and try again.
    (2) You don't need two parallel ports for this  cable  configuration,  you
        can hook the indicated cables up to the primary parallel port.

  The following diagrams are pictured as viewed  from  the  solder  end  (back
side) of the plug. It may be of help to you that the numbers are often printed
in small letters onto the plug itself. When wiring the interface cables,  make
sure that they are not too long: a cable longer than  about  two  meters  will
possibly not work, especially if it isn't shielded at all.

  The PC parallel port (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 port (male 6 pin DIN connector):

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

  The Commodore 1541 drive VIA#1 periphery chip:

                     | | | | | | | | | | | | | | | | | | | |
                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                   | 40                                   21 |
                   |)                                        |
                   | 1 2 3 4 5 6 7 8 9                    20 |
                   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                     | | | | | | | | | | | | | | | | | | | |

                       |             |
                       +------+------+
                          PA0 - PA7

  You can find the VIA#1 by searching for a chip on the motherboard  that  has
the type number 6522 on it and none of its pins 2-9 are connected to any other
chip.

  The X1541 interface connects the following pins:

                 CBM drive serial port   PC parallel port

                       2    Gnd --------- 18-25 Ground
                       3    Atn ---------- 1    Strobe
                       4    Clk --------- 14    AutoFeed
                       5    Data -------- 17    Select
                       6    Reset ------- 16    Init

  Although the Commander doesn't make use of it, the original specification of
the X1541 interface requires the short connection of pins  2  and  15  on  the
parallel port plug, since X1541 uses it for autodetection. If  you  intend  to
use other transfer  programs  with  the  interface  or  want  to  access  your
Commodore drive under the emulators, you might want to do this alteration,  as
well.

  You have to connect the X1541 interface to an  SPP  or  PS/2  parallel  port
because the lines used by this cable are not necessarily bidirectional on  EPP
and ECP parallel ports. This interface should work with all kinds of Commodore
drives and their clones.

  The XE1541 extended interface connects the following pins:

      CBM drive serial port   PC parallel 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 interface, unlike the X1541 interface, needs  electronical  components,
namely diodes, to decouple the data lines of the PC parallel port while the PC
receives data from the Commodore drive. You have to solder them  right  before
each of pins 1, 14, 16 and 17, their cathodes pointing towards the pins.  Note
that you should primarily use BAT85 diodes or other Schottky-diodes, like  the
1N5819. If you can only get 1N4148 diodes then you can try them but be warned,
they may make the cable inoperable on certain parallel ports.

  You can connect the XE1541 interface to any type of parallel port and it has
no common lines with the XP1541 interface therefore you can connect them  both
to the same PS/2, EPP or ECP parallel  port,  using  a  Y-shaped  cable.  This
interface should work with all kinds of Commodore drives and their clones.

  The XH1541 hybrid interface connects the following pins:

          CBM 1541 VIA#1      PC parallel port      PC parallel port

            2    PA0 --------- 13    SelectIn ---->|- 2    Data 0
            3    PA1 --------- 12    PaperEnd ---->|- 3    Data 1
            4    PA2 --------- 10    Ack --------->|- 4    Data 2
            5    PA3 --------- 11    Busy -------->|- 5    Data 3
            6    PA4 ----------------------------->|- 6    Data 4
            7    PA5 ----------------------------->|- 7    Data 5
            8    PA6 ----------------------------->|- 8    Data 6
            9    PA7 ----------------------------->|- 9    Data 7

  This interface also needs diodes, you have to solder them right before  each
of pins 2-9, their cathodes pointing towards the pins. The best diode for this
interface is the 1N4148 or equivalent.

  You can connect the XH1541 interface to any type of parallel port and it has
no common lines with the X1541 interface therefore you can connect  them  both
to the same SPP or PS/2 parallel port, using a Y-shaped cable. This  interface
works with 1541 drives and compatible clones only.

  The XP1541 parallel interface connects the following pins:

                     CBM 1541 VIA#1      PC parallel port

                       2    PA0 ---------- 2    Data 0
                       3    PA1 ---------- 3    Data 1
                       4    PA2 ---------- 4    Data 2
                       5    PA3 ---------- 5    Data 3
                       6    PA4 ---------- 6    Data 4
                       7    PA5 ---------- 7    Data 5
                       8    PA6 ---------- 8    Data 6
                       9    PA7 ---------- 9    Data 7

  You have to connect the XP1541 interface to a PS/2, EPP or ECP parallel port
because the data lines are unidirectional on SPP parallel ports. If you have a
PS/2 parallel port then  you  can  connect  both  the  X1541  and  the  XP1541
interface to the same parallel port, using a Y-shaped cable. If  you  have  an
EPP or ECP parallel port then you can either use the XE1541 cable or build two
separate cables and buy a secondary, cheap, old SPP parallel port card for the
X1541 interface. This interface works with 1541 drives and  compatible  clones
only.

  Please, note that neither the XH1541 interface or the XP1541 interface is  a
substitute for the original X1541 interface or the XE1541 interface, you  have
to connect two cables to the Commodore drive and the PC at the  same  time  to
acquire the extended transfer capabilities. Don't connect the XH1541 cable  or
the XP1541 cable alone to the Commodore drive because neither of them  contain
a GND line: plugging them without the X1541 cable  or  the  XE1541  cable  may
short circuit your machines and damage the periphery chips. Always connect the
XH1541 interface or the XP1541 interface to your Commodore drive and  your  PC
before switching either of them on and switch both  machines  off  before  you
pull them out.

  In 1541 drives nothing is defined to any of the  bits  of  Port A,  you  can
connect the XH1541 interface and the XP1541 interface without any  problem. In
1541C drives, bit 0 of Port A is used for the detection of the head being over
track 1. After stripping this connection off of the chip,  you  will  have  to
change the DOS ROM to that of the 1541 or the 1541-II;  otherwise  you'll  get
strange results when the drive is seeking because the DOS tries to rely on the
detector line which doesn't exist anymore. In 1541-II drives bit 0  of  Port A
is grounded, strip this connection off of the chip. In 1571 drives  there  are
several lines connected to the bits of Port A therefore you  can  use  neither
the XH1541 interface or the XP1541 interface with them.

  If you already have a floppy speeder like Speed DOS or Dolphin DOS  in  your
1541 drive then you probably have a parallel plug at its rear. In   this  case
you have many options of implementing the XP1541  interface.  You  can  create
another cable to connect the drive to the PC with.  You  can  also  split  the
cable between the drive and the C64 into a Y-shaped cable,  one  end  plugging
into the drive, another into the C64 and the third one into the PC,  in  which
case remember not to plug the cable into the C64 and the PC at the same  time.
However, your best choice is creating a small converter imitating the C64 user
port on one side and plugging into the PC parallel port on the other side.

  If your 1541 drive has no parallel capabilities then you might still want to
create a plug at its rear. This way there will be no cable always hanging  out
of the drive and with another cable you'll be able to  use  parallel  transfer
with the C64, too. Please, note that the parallel copy programs  for  the  C64
may require some  additional  connections.  Read  their  documentation  before
soldering so that you can connect the additional pins to the plug, if needed.
