Product Reference
Floppy Disk Interface
The onboard floppy disk controller and ROM BIOS support one or two floppy disk drives in any of the standard DOS formats shown in Table 2–22.
Table 2–22. Supported Floppy Formats
Capacity | Drive Size | Tracks | Data Rate |
| | | |
360K | 5-1/4 inch | 40 | 250 kHz |
| | | |
1.2M | 5-1/4 inch | 80 | 500 kHz |
| | | |
720K | 3-1/2 inch | 80 | 250 kHz |
| | | |
1.44M | 3-1/2 inch | 80 | 500 kHz |
| | | |
Floppy Drive Considerations
Nearly any type of soft-sectored, single or double-sided, 40 or 80 track, 5-1/4 inch or 3-1/2 inch floppy disk drive is usable with this interface. Using higher quality drives improves system reliability. Some considerations about the selection, configuration, and connection of floppy drives to the Little Board/486e CPU include:
!Drive Interface—The drives must be compatible with the board’s floppy disk connector signal interface, as described below. Ampro recommends any standard PC-or AT-compatible 5-1/4 inch or 3-1/2 inch floppy drive.
!Drive Quality—High quality DC servo direct drive motor floppy disk drives must be used.
!Drive Select Jumpering—Jumper both drives for the second drive select (standard on PC drives).
!Floppy Cable—For systems with two drives, a floppy cable with conductors 10-16 twisted between the two drives must be used. This is standard practice for PC-compatible systems.
!The Little Board/486e CPU has a 2mm floppy port connector. The development kit contains an adapter board and a 2-mm cable that can connect the floppy drive to the Little Board/486e CPU. The adapter board has an additional connector that can connect a second floppy drive.
!Drive Termination—Resistive terminations should be installed only on the drive connected to the last interface cable connector (farthest from the board). Near-end cable termination is provided on the Little Board/486e CPU.
!Head Load Jumpering—When using drives with a Head Load option, the drive must be jumpered for head load with motor on rather than head load with drive select. This is the default for PC-compatible drives.
!Drive Mounting—If a floppy drive is mounted very close to the Little Board or another source of electromagnetic interference (EMI), a thin metal shield may need to be placed between the disk drive and the device to reduce the possibility of EMI.
