Message-ID: <232@intelca.UUCP>
Date: Tue, 20-Mar-84 15:23:50 EST
Article-I.D.: intelca.232
Posted: Tue Mar 20 15:23:50 1984
Date-Received: Thu, 22-Mar-84 01:17:25 EST
References: <17662@sri-arpa.UUCP>
Organization: Intel, Santa Clara, Ca.
Lines: 26

>> HOW DO YOU CONTROL THE HALF-STEPPING ON THE APPLE II DISK DRIVE?

Briefly,
    It has four phases controlled by:
C080 = stepper motor phase 0 off
C081 = stepper motor phase 0 on
C082 = 1 off
C083 = 1 on
C084 = 2 off
C085 = 2 on
C086 = 3 off
C087 = 3 on

Timing is very critical, I suggest you adapt the DOS routines at:
B9A0-B9FF SEEKABS routine
BA00-BA10 Delay routine
BA11-BA28 Delay table

A good discussion of the Apple ][ disk (including stepping motor) is in:

"Beneath Apple Dos", Don Worth and Pieter Lechner

^ ^     Glen Shires, Intel, Santa Clara, Ca.
O O     {pur-ee,hplabs,ucbvax!amd70}!intelca!glen
 >
\-/    --- stay mellow