CARPENTR@SERVAX.BITNET (RALPH=CARPENTER) (10/01/89)
Mike Wertheim (mw22+@andrew.cmu.edu) asks: |I recently bought a used Unidisk (no documentation) for my //c. I |attached it to the external drive port, and it appears as S5,D1. | |I would like the drive to appear as S7,D1 so that it will boot |instead of the built-in drive. Is there any way to do this? Matthew Lee Stier (sun!mstier or mcnc!rti!sunpix!matthew) replies: > >>>>>>>>Take the disk out of the internal drive. <<<<<<<< > >Really. The Boot code for the UniDisk 3.5 compatible Apple //c's >will boot the first Smartport drive if it can't find anything in the >internal drive. (In your case the first Smartport device is your >UniDisk 3.5 @ S5,D1) The following info was posted on this list a few months back; unfortunately, I neglected to retain the name of the contributor (may his tribe increase). I've been happily using this method of booting my //c's 3.5" since. It's fractionally faster than Matt's omit-disk trick, since it deliberately turns off the internal drive motor instead of waiting for it to time out. This method is useful for those older //c's (ID=$FF and $00?) that don't have the Unidisk ROMs. =================================================================== Re: making a disk to put in slot 6, to automatically boot slot 5 There are a couple of tricks to this. First, make sure that the first byte of block 0 is a 1. The actual code begins at relative byte 1 of block 0. (The 1 indicates how many sectors, that's right, SECTORS, to read in. The disk controller has the capability to read the entire track into memory, on bootup, but Apple never used the capability for some reason.) Next, make sure you deactivate the 5.25" drive's motor with an access to $C088,X. (If you're always booting from slot 6 you can just access $C0E8.) This might not be necessary on the IIgs, but it sure is on the IIc, because the IIc waits for the 5.25" drive to turn off before it will turn on the 3.5. (That's because both devices use the same softswitches for different purposes.) After that, just jump to $C500, the PR#5 entry point. So the complete code for block 0 should be: 00: 01 01: 2C E8 C0 04: 4C 00 C5 ====================================================================== _______________________ / \_____________________________________________________ | Ralph Carpenter \ | Dept. of Psychology InterNet: CarpentR%SerVax.Bitnet@MITvma.MIT.EDU | | Florida Atlantic U. Bitnet: CarpentR@SerVax SoBell: (407) 367-2616 | | at Boca Raton GEnie: Ralpho CI$: 74015.644@compuserve.com | \_____________________________________________________________________________/ CC : SMTP@INTERBIT CC : RALPHO@FAUVAX