-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* 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 -*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-* 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.