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.file extension SDK - ShrinkIt compressed Apple II file archive
File extension SDK description:
A ShrinkIt whole-disk archive is an .SHK file which is usually labeled ".SDK" to show that it is a Shrinked diskette. An .SDK file can archive a 3.5" diskette (both sides) or 5.25" diskette (one side). Most are archives of 5.25" DOS 3.3 diskettes produced by 8-bit ShrinkIt.
A whole-disk ShrinkIt archive retains all data bytes on a diskette, including files, Catalog/Directory sectors, empty tracks, and DOS if present. An .sdk file of a DOS 3.3 5.25" disk created by 8-bit ShrinkIt also preserves volume number-- important for some games and utilities which depend upon volume numbers to identify disks. (5.25" whole-disk archives created by GS-ShrinkIt do not preseve volume number.)
8-bit/IIe ShrinkIt can be used to fully unshrink any Apple II .SHK file _except_ .SHK files which contain files with GS/OS resource forks and .SEA files. For this reason, 8-bit ShrinkIt should not be used to unshrink .SHK file archives containing GS programs unless you know that none of the contained files has a resource fork.
GS-ShrinkIt can handle nearly all kinds of Apple II .SHK and .SDK files. It will not handle shrinked 5.25" DOS 3.3 .SDK files created by 8-bit ShrinkIt. In fact, most users automatically use 8-bit ShrinkIt to create and unshrink .SDK files of old 5.25" wares. (Balloon does not currently support whole-disk archives.)
Naturally, things are somewhat more crowded on 64K Apple II's. On these machines, the functions are separated. SHRINK creates .SHK files and UNSHRINK unshrinks them.
On a PC, the utility NuLib (v3.24) lets you view contents and unshrink most kinds of .SHK files. (There is a handy option to unshrink and convert Apple II text files to PC text format.) It will not unshrink IIgs files with resource forks.
Here is a simple one-line batch (text) file program for easily viewing the contents of .shk files you download to a PC (just double-click on the file name): c:\nulib\nulib v %1 |more
The above is for NuLib.exe located in folder c:\nulib . Save the text as nulibv.bat in c:\nulib and tell Windows to use c:\nulib\nulibv.bat as the 'application to perform action' for doing an Open. (You do this by selecting View--Options in the My Computer window and editing the file type info for .shk files.)
NuLib can also convert 5.25" .SDK files into .PO (ProDOS order) disk images which can be used by Apple II emulators. This works for .SDK files produced by 8-bit ShrinkIt but not for those produced by GS-ShrinkIt.
The unshrinking process is very speedy and the size of a compressed ShrinkIt file is, often, around half that of the original files it contains. This makes .SHK files very handy for archiving your software. And, since a ShrinkIt file also preserves filetype information of contained files, ShrinkIt has become the preferred format for uploading and storing Apple II files on the internet.
Associated applications to file extension SDK:
ShrinkIt
Company / developer:
Andy Nicholas
ShrinkIt is a utility program for archiving files and disks. "Archiving", in this usage, refers to the process of placing files or disks "within" another file -- the archive file. Archiving is usually done to prepare the files/disks for transmission via modem, or for storage purposes. Thus, an archive file, whether created with ShrinkIt or another archiving utility, will be a file which serves as an envelope, containing one or more other files, or complete disks. There are a number of reasons for archiving files before transmitting them with a modem. The principal reason is that an archive provides a means of sending the "attributes" of a file -- its filetype and other information -- along with the file itself. An archive also allows several related files (or an entire disk) to be packed together into a single file. True archiving utilities will also have the capability of compressing the files they contain to minimize the transmission time and disk space the archive requires.
ShrinkIt uses a highly efficient compression algorithm known as dynamic LZW, and creates archive files with a format called NuFX. For technical documentation of the format of NuFX archives, refer to the File Type Note for filetype $E0, auxtype $8002. (File Type Notes are available from Apple Programmers and Developers Association.) ShrinkIt and ShrinkIt-GS are currently the standard archiving utilities for Apple II telecommunications. ShrinkIt can unpack files which have been archived with ShrinkIt, as well as those which have been packed with certain other file-packing utilities, such as BLU and ACU.