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appdos31_notes.txt

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+
+Apple DOS 3.1 Source Code - Notes
+****************************************************************************************
+
+
+* The initial release of DOS 3.1 had a handful of bugs, two of which were particularly 
+  frustrating for users. The first bug prevented the ability to successfully run the
+  MASTER.CREATE program. You could INIT a slave disk just fine, but not a master
+  disk. Indeed, I've confirmed this with every DOS 3.1 disk image that I could find.
+  Apparently, a patch was published by a user group that fixed the issue, and that
+  patch was at some point incorporated in some of the later DOS 3.1 disks that were
+  distributed by Apple (it seems they didn't change the 3.1 revision number when they
+  released the updated disks). Try as I might, I haven't found any differences in the
+  RAWDOS binary or DOS/boot sectors on any of the disk images that I have located,
+  and I haven't located any documentation that provides any details on this particular
+  patch.
+
+  With that, I studied the source for a bit and pretty quickly found what the problem
+  was, and applied (what turned out to be) a simple two byte patch.
+
+  The second bug prevented Applesoft from READ'ing or WRITE'ing lines numbered greater
+  than 255. The patch that addressed this problem, while apparently not on the initial
+  release of DOS 3.1, WAS found on every disk image that I have located.
+
+  This source file, the included boot disk image, and the RAWDOS binary on the disk
+  image, all incorporate these two simple patches (thus the 'Patched Release'
+  reference at the top of the source file).
+  
+* This source file obviously includes the Apple DOS RWTS low-level subroutines
+  written by Steve Wozniak and Randy Wigginton. The original source listing file is
+  posted on the CHM website and named "Apple_DOS_RW_30May1978.txt".
+  
+  The object code for this part of the source was compared to sectors extracted from
+  an Apple DOS 3.1 master disk, as well as the RAWDOS binary distributed with DOS 3.1,
+  and somewhat surprisingly only a single byte was changed. The change occurs at
+  appdos31.asm source line number 4877. The delay byte in the original is $5F, and
+  with DOS 3.1 it's $FF.
+  
+  Note that this source not only contains the RWTS low-level subroutines that were
+  made available, but also the necessary RWTS main entry point routines.  The original
+  source listing for this part of RWTS has not been made available as of this writing.
+  With that, I took a stab at commenting that part of the disassembled code.
+  
+* This source file will produce a binary that is identical (with the one exception
+  noted at the top of the source file) to the RAWDOS binary image that was included
+  on the DOS 3.1 master disk.
+
+  The resulting binary was placed on a DOS 3.1 master disk image and named as RAWDOS,
+  the disk was booted, and then the MASTER.CREATE program was run (because we have the
+  necessary patch! :)) to create a new master disk. The new disk (INIT'ed with the
+  newly assembled RAWDOS binary) was tested and found to be working perfectly.
+  
+  And (just for the fun of it :)), I also placed the various components of this binary
+  directly on the appropriate sectors of a disk image, set some of the initial EC3, IOB,
+  and various 'MISC BUT REQD CELLS' values that are required to boot, and it also boots
+  and runs just fine.
+  
+* The disk image (Apple DOS 3.1 Master - AFS.nib) included with this archive is the
+  result of running MASTER.CREATE with the assembled RAWDOS binary, and then copying
+  (loading/saving) the additional files that were distributed with the DOS 3.1 master
+  disk from an original 3.1 master disk image. It is in the 'nibblized' image format,
+  which should be supported by most (if not all) Apple II emulators.
+
+
+
+  Scott LaBombard
+  labomb@rochester.rr.com
+  12/07/2013
+  
+  

how-to.txt

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+ 
+How To Create A Customized Apple DOS 3.1 Master Disk Image
+---------------------------------------------------------------------------
+
+1. Customize the appdos31.asm file as you wish. You may need to change
+   the syntax to suit the assembler that you choose to use. Pay close
+   attention to the overall size of the binary generated, and to page
+   boundaries as per the warnings throughout the comments in the source.
+
+2. Assemble the source to produce a binary. Rename the binary to RAWDOS.
+   You may need to include the file attributes in the name depending on
+   the utility you use to add the binary to a disk image.
+   
+3. Open a DOS 3.1 master disk image in a disk image manipulation utility,
+   and then copy the newly assembled binary to the image, replacing the
+   existing original RAWDOS binary.
+   
+4. Boot the image in an Apple II emulator. Many emulators do not support
+   booting a 13 sector per track image directly, but that isn't a problem
+   (see Note 1 below for more detail):
+   
+	a. Boot a DOS 3.3 master disk image that contains the Apple's
+	   BOOT13 binary.
+	   
+	b. Enter "BRUN BOOT13" and wait for the prompt to enter the
+	   slot number to boot from (default=6).
+	   
+	c. Eject the DOS 3.3 disk and mount the DOS 3.1 image that has
+	   your custom RAWDOS file on it.
+	   
+	d. Press enter.
+	
+5. Once the DOS 3.1 disk has booted, enter "RUN MASTER.CREATE" and follow
+   the directions.
+   
+   
+Note 1:
+
+Apple's DISK II disk controller is outfitted with two 256x8 PROMs. One of
+these PROM's contains the 'Phase 0' boot code that is responsible for
+loading up and running the 'Phase 1' code located sector 0 of track 0 on
+a DOS boot disk. The second PROM is generally referred to as the 'logic
+state sequencer' PROM and is used to control disk accesses.
+
+The initial shipments of Apple's DISK II disk controller were outfitted with
+P5 (boot) and P6 (logic sequencer) PROMs. These versions of the PROMs were
+specific to 13 sector per track disks, which was the format used when DOS 3.1
+(and DOS 3.2) was released. With the release of DOS 3.3, the format changed
+to 16 sectors per track. Apple made newer PROMs available (P5A and P6A) to
+support the new disk format. While you cannot boot a 13 sector per track
+disk directly with the newer P5A boot PROM (it is specific to 16 sectors
+per track), the P6A logic-state sequencer has no issue reading and writing
+both 13 and 16 sector per track disks.
+
+Indeed, that is why Apple provided the BOOT13 binary (and the "BASICS"
+diskette) when DOS 3.3 became available. With a controller outfitted with
+the newer PROMs, it's simply a matter of booting a DOS 3.3 disk, and
+entering 'BRUN BOOT13'.
+
+   
+ Scott LaBombard
+ labomb@rochester.rr.com
+ 12/07/2013

shepdos_vs_appdos31_diffs.txt

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+
+This document summarizes where changes occur in the Apple DOS 3.1 source code
+as compared to the pre-release Apple DOS source written in 1978 by Paul Laughton,
+then an employee of Shepardson Microsystems. 
+
+No attempt is made to explain why the changes were made... that is left to the
+reader to determine :).
+
+
+-----------------------------------------------------------------------------------
+source		source
+line #		line #
+shepdos.asm	appdos31.asm	change to appdos31.asm source - comments
+------------	------------	---------------------------------------------------
+
+ 35		 62		label DR1B moved up a line
+ 47		 75		BNE destination addr changed 
+ 51		 79		BNE destination addr changed
+ 55		 83		'find end of DOS' JSR to a PATCH
+ 382-389			instructions removed
+ 583-584			instructions removed
+ 644-646			instructions removed
+		 663-664	instructions added
+ 654				instructions removed
+ 826-827	 840-841	instruction order reversed
+ 1101				instruction removed
+ 1107-1108	 1120-1121	'verify a file' JMP to a PATCH
+ 1245		 1256-1259	instructions removed, new instructions added
+ 1274-1278			instructions removed
+ 1498				instruction removed
+ 1610				instruction removed
+ 1626				instruction removed
+ 1653				instruction removed
+ 1666				instruction removed
+ 1689-1691	 1688		instructions removed, JMP to AS r/w PATCH
+ 1694		 1691		BMI destination addr changed
+ 1695-1696			instructions removed
+ 1736-1741			instructions removed
+ 2234-2259	 2224-2249	various DB/DW default values differ
+		 2360		instruction added
+ 2406				instruction removed
+ 3670-3675	 3660-3665	various DB/DW default values differ
+ 3688-3699	 3678-3689	various DB/DW default values differ
+ 3720		 3710		DB value differs
+		 3851-3878	'find end of DOS' PATCH code added
+		 3994-4003	'verify a file' PATCH code added
+ 3991-4012	 4021-4042	various DB/DW default values differ
+  
+ 
+ 
+ Scott LaBombard
+ labomb@rochester.rr.com
+ 12/05/2013
+