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