Oliver Praudisch wrote: > > I would like to use a floppy and/or a harddrive for data acquisiton. Does > anyone have any info on tring to do something like that? This comes up now and then on this list. I doubt that anyone is doing this on a low-end PIC. The PIC of course would be fast enough to connect to a floppy disk controller (a 765 or one of the modern equivalents, or a multi-I/O controller) which only does 500kB/s, but you'd have problems writing disks that another computer would understand. In order to be able to read the disks on a PC, you'd have to have a FAT (MSDOS) file system -- not impossible perhaps, but very difficult because of the simple reason that the FAT and directory are stored in 512 byte sectors. Changing these would require reading them, making some changes, and then writing the sector back. The current 16Cxx PICs come with up to ~370 bytes of RAM or so, sadly not enough for a complete sector. I think there are 17Cxx chips with over 512 bytes of RAM, though. If you don't use a file system, but just write data onto the disk as it is generated then you could probably do it -- keep to the 512 byte sectors so that you can use the BIOS (or Linux kernel, or whatever Windoze has) to read from the disk. If you're prepared to write low-level hardware stuff on a PC, then you can use different sector sizes, of course. The 765 has support for sectors of 128 bytes (or even less, with careful reading of the datasheets) and those can be read by PCs. The main reason for not using floppies is power consumption, access time and environmental problems like dust, water, snow, condensation etc. in most outdoor data-logger-type locations. Depending on your storage requirements, you could use serial or parallel EEPROM or SRAM, or even (with addition of external counters or shift registers to generate all those address lines) PCMCIA cards. Frank ------------------------------------------------------------------------ Frank A. Vorstenbosch Mobile: +44-976-430 569 Wimbledon, London SW19 Home: +44-181-544 1865 frank@falstaff.demon.co.uk Office: +44-181-636 3391