junod@sunburn12.DAB.GE.COM (11/09/88)
Posting this for a fellow worker: ------------------------------------------------------------------------ Subject: In-use light for 800K drives Ever since I got my MacII, I've wanted to attach an in-use LED to each of my 800K floppies. There are times when certain programs use more than one floppy (ignoring the hard disk), and I'd really like to know what is going on. This is particularly important for me since I frequently use II in a Mac, the Apple II emulator, which will let one or both floppies operate like Apple II Unidisks. For some reason, Apple does not like including in-use lights on their floppy disk drives for the Macintosh. The purpose of these indicators on other machines is to let you know the disk is being used and shouldn't be removed until the light goes out. But it's still pretty important to know when it's in use on the Mac. Apple DOES include an in-use LED on their 800K "Apple 3.5 drive", but that's only because the drive is used on both Apple IIGS and Macintosh. And unfortunately, you can't connect an external floppy to the MacII. I managed to get a "peek" inside the Apple 3.5 external drive at a local dealer. In addition to the standard Sony drive/controller combination used on all Apple 800K mechanisms, the external drive has a "piggy back" board which attaches between the drive controller and the external cable. This board (which has a SONY part #) provides a connection for a drive LED, a connection for an intelligent manual eject button, and a "pass-through" port for chaining additional drives (on the Apple II). Looking up this part in Apple service literature puts its price at ~ $65.00! I've done a little probing with my DVM, but am unwilling to connect an LED without prior knowledge. A friend of mine tried attaching an LED to one of the leads on the IR head sensor pair, and ended up blowing his drive (and spending over $300 to fix his damage). So my question is, has anybody successfully attached an in-use light to their 800K drive? I know there were a set of drawings for doing this on the 400K drives, but the boards for the 800K drives are different. I have the LED's (small rectangular Telefunken brand), but am not willing to play around finding a connection. What I'd like is a set of detailed instructions (including current-matching or other warnings) of where to connect the LED, what other devices (resistor values, caps, transistors?) to attach between the board and the indicator. Thanks in advance! Paul Christensen GE Aerospace/Advanced Technology Laboratories : : : PCHRISTENSEN%ATL.DECNET@GE-CRD.ARPA : : : -------------------------------------------------------------------------------- -- Michael F. Junod (Mike) Domain: mjunod@atl.GE.COM RCA Advanced Technology Laboratories UUCP: ...!mcnc!ge-rtp!ge-dab!junod Moorestown Corp. CTR., Rt. 38 Phone: (609) 866-6622 Moorestown NJ, 08057 DialComm: 8*777-6622