Table of Contents
ALLCF, Compact Flash or Disk-On-Module board for RC2014
ALLCF is one of many CF & DOM boards for RC2014. The main difference is ALLCF is designed to interface with all brands of CF disks.
- Compact Flash or Disk-on-module interface
- Programmable EPM7032S controller
- Four jumper selectable base addresses, 0x10, 0x18, 0x90, 0x98
- RC2014 compatible
Theory of Operation
ALLCF enhances the standard RC2014 CF board with three improvements:
- IORD signal termination and filtering. Some fast CF disks can generate significant noise when its data are all switched from low to high, enough to cause ground bounce of sufficient magnitude to glitch its IORD line resulting in more data being clocked out of its FIFO buffer. A low-pass filter of 100 ohm resistor and 100pF capacitor can significantly reduce the effect of ground bounce on the IORD control line.
- Proper setup time from chip select to read/write. Many CF disks requires setup time from CF chip select asserted to CF read or write signal asserted. ALLCF inserts one clock period delay from chip select asserted to read/write asserted.
- Data bus isolation. The ground bounce mentioned above is caused by simultaneous switching of multiple data signals driving into capacitive RC2014 backplane. By isolating the RC2014 data bus from CF data bus, the CF disk no longer drives a capacitive bus and the corresponding ground bounce effect is mitigated.