New interface xu1541
What is the xu1541?
The xu1541 is the modern way to connect CBM IEC bus devices to todays USB equipped PCs and it is meant to replace the printer port solutions based on the so-called originalx1541 cable. The xu1541 interface allows you e.g. to attach a VIC1541 disk drive to your desktop PC as depicted below. This allows for easy transfer of disk images from and to the old units and helps you preserve your ancient data.
The xu1541 is a proprietary interface. It doesnottransform the VIC1541 into a standard usb mass storage compliant device. Instead it provides a means to send low level IEC commands forth and back via the USB. PC software developed to support this interface may then directly access the disk drive and the contents of a disk inserted. It should also be possible to access other IEC devices like printers. Currently e.g. the git version of theOpenCBMsoftware supports this interface.
This project is still under development. It works with a variety of CBM disc drives (1541, 1541-II, 1570, 1571, 1581, SX-64's internal floppy). There have been also some tests on different brands and types of PC, running on Windows, Linux, and Mac OS X.
However, the xu1541 is currently only recommended for people who are willing to cope with glitches and will perhaps even do some testing and bug hunting. For example, you should be able to flash a new firmware on your own.
We hope to have a end-user-proven version, soon. Stay tuned!
The xu1541 was designed to be made of easily obtained parts, easy to assemble and cheap. In order to avoid having to write all the necessary PC software, the xu1541 was designed to easily integrate into existing software developed for the original x1541 parallel cable family.
The xu1541 is not meant to be the all-in-one cable. It is meant to connect the PC to CBM IEC serial periphery like the VIC1541 floppy disk drive. It cannot act as CBM IEC client and can thus not be used to emulate a floppy disk drive with the PC. Furthermore it does not support the so-called nibblers, meaning that the cable cannot be used to transfer copy protected disk images from and to the VIC1541. These limitations are due to the simplicity of the design. A CBM IEC floppy emulation requires an interface to respond faster to incoming requests from the C64 than the xu1541 currently can do with the software USB implementation. Nibbler support requires a 8 kilobytes (one VIC1541 disk track) buffer which exceeds the 1 kilobytes RAM present in the Atmega8 used on the xu1541. These options are left for future and more complex and more expensive USB to IEC solutions.
The xu1541 is fully compatible with all tools delivered with the OpenCBM package. Therefore, it fully supports e.g. the It allows to control the disk drive (e.g. read the drive status or the directory), it allows to format a disk, to copy single files from and to the disk, and to copy entire not-copy-protected disk images (d64 images).
The xu1541 was developed on and for a Linux PC and the cbm4linux toolset, the linux version and predecessor of OpenCBM. In the meantime, it has been fully ported to OpenCBM, that is, it runs on Windows and Linux now. There is also a port of OpenCBM to MacOS (cbm4mac) which should finally be able to bring cheap and simple c64 file transfer to the MacOS platform..