del@pilchuck.UUCP (Erik ) (05/03/86)
[eatme] I am looking at an AT or compatible and have a question re: disk controller. My current PC has a 3.5" micro disk attached to it. If I get an AT, I figure I'll need the 1.2M floppy, a 360k floppy, and I would hate to loose my 3.5". Since the AT does not provide for an extra drive connector coming out the back of the thing, the question is: are the hardware select lines there and just no additional connector provided, or is it impossible? I could easily manufacture a cable to connect my 3.5 inch drive if the hardware support is there, but otherwise, what are my options? Thanks.
bmw@aesat.UUCP (Bruce Walker) (05/09/86)
In article <333@pilchuck.UUCP> del@pilchuck.UUCP (Erik ) writes: |My current PC has a 3.5" micro disk attached to it. If I get an AT, I |figure I'll need the 1.2M floppy, a 360k floppy, and I would hate to |loose my 3.5". Since the AT does not provide for an extra drive |connector coming out the back of the thing, the question is: are the |hardware select lines there and just no additional connector provided, |or is it impossible? The IBM-supplied AT controller (manufactured by Western Digital) has drive select (and motor-on) signals for only two floppy drives of either density. The bits in the I/O register that were defined for drives three and four on the PC/XT controller, are marked as "reserved" on the AT controller. If you felt adventurous, you could piggy-back some 7438's on top of the existing circuitry and lash up an extra connector, but it would be the definitive "hack job". In a nut shell, and WRT the "official" controller: no, there are no select lines, and no, there is no additional connector, but no, it is not impossible, just very difficult. Take a look at some third-party disk controllers, someone (maybe Taiwanese) may have built just what you're looking for. Bruce Walker {allegra,ihnp4,linus,decvax}!utzoo!aesat!bmw "Over here is the power supply for my new stereo ... and down here is where we store the spent fuel rods."