Q: Why 1541EMU does not support the XA1541, XE1541 or X1541 type of cable?

A: PC LPT port I/O operations are too slow for that. It certainly would be possible to support these at the stock serial bus speed, but fastloaders would not work.

Q: I don't want to buy a PCI bus LPT port card. Is there anything that I could do to improve the performance of an ISA bus or motherboard integrated LPT port?

A: There are a couple of BIOS settings that can be of use:

Q: Why is this a DOS program? Isn't DOS an obsolete operating system?

A: 1541EMU has exceptionally hard realtime requirements in the microsecond range. Multitasking operating systems are obviously out of question because of this.

Q: Where can I buy the cable needed for 1541EMU? Can I manufacture and sell those myself?

A: The type 1 cable is available from the X1541 Shop. Anyone can freely manufacture and sell those.

Q: It seems to me that 1541EMU does not work with some fastloaders no matter how carefully I try to adjust the timing by trial and error. Why is that?

A: Some Commodore 64 fastloaders use the serial bus /ATN signal for timing purposes. Each active edge of this signal generates an LPT port IRQ on the PC computer. Acknowledging these hardware interrupt requests is a relatively slow operation from the viewpoint of this application. It can happen that a high rate of these interrupts causes the disk drive emulation to temporarily fall behind so much that fastloader data transfer can get out of sync. This is a limitation of the PC hardware and avoiding it by using the Automatic-EOI mode of the PC interrupt controller would make it necessary to make modifications into the DPMI provider (currently 1541EMU uses CWSDPR0.EXE) and I am somewhat hesitant to do that.