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Getting .dsk Disk Image files from a PC to a 64k Apple II
ref: PRODOS288blocks.sdk (unshrink to 5.25" diskette using ShrinkIt)
I. Creating a 288-block ProDOS Diskette
Normally, a ProDOS 5.25" diskette has 35 tracks at 8 blocks per track for a total of 280 blocks, with 273 blocks available after formatting. Disk image (.dsk) files typically require 283 blocks.
In order to get the blocks needed to hold a .dsk image file on a 5.25" diskette which can be accessed on a standard Disk ][ drive, you need to ...
1- change FILER or some other ProDOS formatting utility so that it will format 36 tracks
2- edit a couple sectors on the 36-track disk to free up a few extra sectors.
The reason for the 36-track limit is that many Disk ][ drives can not handle more than 36 tracks. Step 2 is necessary because formatting will use up all but 1 block on track 0, which would leave you with 281 free blocks-- 2 short of the required 283.
The PDOS288 disk has a FILER program modified to format 36 tracks and allocate 288 blocks. There is, also, a ProDOS (v1.9) modified to handle up to 288-block 5.25" diskettes. (The basic directions-- for 40-track disks-- come from Beneath Apple ProDOS with some updating from Ross Holmes in Computist #76.)
Running the FILER program and doing a format will get you a 288-block 5.25" diskette with 281 free blocks. To free up more blocks, use the Copy II Plus Sector Editor to modify two sectors:
Track 0, Sector $03: Change the first byte (Byte $00) from $01 to $1D and save the changed sector. (This deallocates Blocks 3, 4 , 5.)
Track 0, Sector $0B: Change the fourth byte (Byte $03) from $03 to $00 and save the changed sector. (This tells ProDOS not to look for or try to use any further root directory blocks.)
The resulting diskette will have 288 blocks with 284 free blocks-- one more than is required for holding a .dsk file!
You can use a 36-track disk copy utility-- such as later versions of Disk Muncher-- to make duplicates of the 288-block diskette.
II. Using the 288-block Diskette for .dsk file transfers.
With a standard NULL modem connection and a telecom utility which runs under ProDOS 8, you can transfer a .dsk file from PC to your 288-block diskette so long as the ProDOS 8 you boot and run under is the one on this disk (or one like it).
The .dsk file can be transformed to disk form using DSK2FILE v3.0 (also on this disk). DSK2FILE v3.0 can run on a 64k Apple II+. As above, you need to be running under the ProDOS 8 on this disk. (Note: the target diskette must be formatted; and, you should pick the correct 'ordering' from the DSK2FILE memu-- usually, this will be DOS 3.3 ordering.)
III. Another Way
A different approach is to use Nulib (e.g. v3.24) on the PC to compress a 5.25" .dsk image file into a .shk file. This file can be NULL modemmed to your Apple II with no need for a special diskette or ProDOS because it will fit on a regular 5.25" ProDOS diskette.
Once transferred, the .shk file can be unshrinked (using the version of ShrinkIt selectable from the disk startup menu) to a 288-block disk. Using DSK2FILE, it can then be transformed into diskette form as discussed above. ShrinkIt and DSK2FILE need to run under the 288-block ProDOS on this disk.
For more info on ShrinkIt and DSK2FILE, see the FAQs and/or post a question to comp.sys.apple2.
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