(Maarten ter Huurne, Mari v/d Broek, MSX Mailinglist)

You can easily replace a 8250/55/80 drive with a standard PC disk drive. The only modification you need, is to place a jumper over pin 33 and 34 of the second drive connector on the main board. Pin 33 is ground and pin 34 is /RDY, the ready signal, a signal that modern PC drives no longer have. Connecting the pins will tell the 8250/55/80 that the drive is always ready, the 8250/55/80 DiskROM has no problems with that.

For the pin numberings, refer to the connector section.

Troubleshooting:

• Drive doesn't work and LED of it keeps lit: you put the connector on the drive upside down. Reverse the connector and try again.
• The drive only works when I access it as drive B: (by e.g. FILES "B:". Check if there is a D(rive)S(elect) jumper on the diskdrive... Many diskdrives do not have jumpers but are soldered (SMD-resistor!). Be sure that DS=0 for drive A en DS=1 for drive B. If there is no jumper, or you can't solder SMD it is possible to solve the problem... Open the connector at the side of the drive and remove the flatcable from it... With a sharp knife you can split the cable between wire 9 and 10 en 12 and 13 (over a length of about 4 cm!)... If you turn this piece of cable (3 wires) 180 degrees and put it back in the connector, DS0 and DS1 are switched from there place and it should work then.
• Errors occur when a HD drive was put in: you cannot use the drive as a HD drive. So use only floppies formatted as Double Density. Sometimes you need to put a piece of tape over the HD hole in the disk to make it work. Better is to short the sensor that checks for the HD hole.

Note that it's possible to put two drives on one cable, as long as one reacts to DS0 and the other to DS1.