Abstract: A magnetic bubble memory based floppy disk emulating system is provided which is capable of emulating available industry standard floppy disk drives with a simple, microprocessor controlled system in which direct memory access techniques are used to free the microprocessor to perform the control functions necessary to emulate single/double density and floppy/minifloppy disks.

Abstract: An electronic circuit module and a compatible module holder are provided which are particularly suitable for magnetic bubble memory applications. The holder has power-down warning and write-protect circuits utilizing light emitting diodes (LEDs) and photo-transistors to detect motion prior to removal of the module, and to detect the presence of a reflective sticker to write enable, respectively. Moreover, the module has separate ground buses for each power supply voltage to prevent circuit damage due to relative polarity reversal in case of ground non-connection upon insertion or removal of the module from the holder.