Path: utzoo!utdoe!generic!pnet91!sb
From: sb@pnet91.cts.com (Stephen Brown)
Newsgroups: comp.sys.apple2
Subject: Re: What is this Rom Routine?
Message-ID: <472@generic.UUCP>
Date: 9 Feb 91 15:21:26 GMT
Sender: root@generic.UUCP
Organization: People-Net [pnet91], Etobicoke, ON
Lines: 26

stc7@cunixb.cc.columbia.edu (Steven T Chiang) writes:
>
>	I was looking at a piece of code the other day, and I ran
>across a jsr to an unfamilar rom routine.  I checked a couple of
>references that I have (Firmware, and Inside the //gs), and couldn't
>find any information on it.
>
>	The routine was $f8fa.  If anyone has any information on it,
>it would be greatly appreciated.  When I jsr it, it will toggle the
>3.5" drive, if there is a disk in it.
>
I checked my WHAT'S WHERE IN THE APPLE (for the II+), and my Monitor Rom
Listings in the Apple IIe Technical Reference (for the Enh. IIe) and F8FA is
not a valid entry point. 

I've got the IIe ref manual here:
F8F9: 06 2D  PRMN2  ASL RMNEM  ; SHIFT 5 BITS OF CHARACTER INTO A
F8FB: 26 2C         ROL LMNEM
F8FD: 2A            ROL A      ; (CLEARS CARRY)
F8FE: 88            DEY
F8FF: D0 F8         BNE PRMN2

As you see, this code is not stable. I would suggest that you not use it.

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