Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!lll-winken!uunet!microsoft!brianw
From: brianw@microsoft.UUCP (Brian Willoughby)
Newsgroups: comp.sys.apple
Subject: Re: what is sweet 16?
Summary: Not so Sweet, no floating point.
Keywords: AutoStart ROM, INTEGER BASIC, 16K Card, early death of Apple hackers
Message-ID: <4015@microsoft.UUCP>
Date: 11 Apr 89 05:10:47 GMT
References: <8904071330.aa29809@SMOKE.BRL.MIL>
Organization: Microsoft Corp., Redmond WA
Lines: 52

In article <8904071330.aa29809@SMOKE.BRL.MIL>, ALBRO@NIEHS.BITNET writes:
> Paul Nakada asks "What is Sweet 16?"
> 
> Sweet 16 is Woz's assembly language machine in the AppleII and /or II+ to
> allow floating point arithmetic.  In a sense, it's the ultimate precursor
> of the SANE routine.

I hate to break it to you, but the Sweet 16 routines do not include floating
point arithmetic by any means! There is a fully descriptive article in an
ancient Byte magazine article which I think was written by the Woz. For
those of you with complete libraries nearby, I'll go home tonight and find the
issue. From memory, the Woz had a thought that BASIC would be much easier to
write with a 16-bit processor, so he simulated one with the instructions he
needed and wrote INTEGER BASIC. The genius of The Woz (in both hardware and
software) never ceases to amaze me! The Sweet 16 routines are available to
anyone who has 64K and the system disk file INTEGER (or an original II, ed.).

Regarding another post, the 50 sector INTEGER is larger because it includes
the Monitor code. It is basically a BSAVE of $D000.FFFF on an Apple II. After
Apple designed the 16K card with the AutoStart ROM on it, they didn't want
the easily frightened nouveau crowd of II users to have the AutoStart disabled
by loading the contents of the old Monitor ROM in the Language Card. Therefore,
the 42 sector INTEGER file is only addresses $D000.F7FF. This is where
LOADER.OBJ0 was born. This code (with the proper Basic calling program) copies
whatever data is in the motherboard ROM at $F800.FFFF into the RAM bank at the
same address. THEN it loads $D000.F7FF with INTEGER Basic. The smaller INTEGER
has all the features (i.e. Sweet 16, Mini-Assembler, HiRes Routines and Basic)
but it lacks the features of the original Monitor ROM (i.e. 6502 Single-Step
and Tracing).

An interesting note, it seems like Apple really wanted to push the AutoStart
ROM. The 16K RAM card with the 24-pin ROM on it permanently disabled whatever
ROM was at $F800.FFFF, and they also tried to prevent it from being overwritten
in the RAM bank. I guess this was a combination of keeping software writers
happy, because they could almost be guaranteed RESET protection, and making it
harder for the hackers to get deep into the guts of the Apple II. In some ways
I feel that this early move started the trend of fewer knowledgable hackers,
and paved the way for the "new generation" of Apple users who learned BASIC
instead of Assembly. Alluding to an earlier post, I can say that my current
software engineering career was built on the struggle I went through with my
Apple II. Before the Plus and AutoStart, you booted into the Monitor without
the fancy "Apple II" title, and I eventually was forced into learning what all
those funny 3-letter mnemonics meant. I can't complain too much now, because I
like the convenience of restarting with RESET. But I still keep the original
non-AutoStart ROM available by a flip of a switch (2732 4K ROMs) for avoiding
the dreaded power-off method of cold-start which wreaks havoc on digital
circuits.


Brian Willoughby                        microsoft!brianw@uunet.UU.NET
                or                      uw-beaver!microsoft!brianw
                or just                 microsoft!brianw