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23 Geos Applications
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GETPIT.ARK
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GETMAC.DOC
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1987-05-28
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Conversion of Packit-compressed Macpaint pictures.
This document will explain the use of the files in this ARK file in
preparing compressed Macpaints for conversion to geoPaint, or other CBM graphic
formats.
Requirements:
C128 with current CP/M system
Mac Attack (LIB 13 MA2V12.BIN), or other Mac->C= converter
CP/M supported disk device large enough to hold .PIT file and component files
Contents:
UNPIT.COM - unPackit program
UNPIT.DOC - Doc for UNPIT
UNPIT.C - C source for UNPIT, dialect unknown
C128LOAD.COM - CP/M to CBM transfer utility
C128LOAD.DOC - Doc for C128LOAD
GETMAC.DOC - this file
UNPIT and C128LOAD are PD CP/M programs, and were not written by me.
UNPIT:
UNPIT is a general CP/M program for uncompressing Macintosh files stored
with Packit II format. It should work correctly with Packit III files,
assuming they have not been password protected. It is reasonable to assume
that the vast majority of BBS and commercial network files will not have any
password protection. It is unknown whether or not this program can handle
Packit I format files, which were not compressed. It does not work with
Stuffit-compressed files, commonly stored with a .SIT extension.
C128LOAD:
C128LOAD is a rather ingenious C128-specific CP/M program for transferring
CP/M files to C= disks. It loads the CP/M file into Bank 1 memory. The user
then immediately CTRL-Enter's out of CP/M, enters MONITOR mode, and saves the
appropriate area of memory to disk. While this places an absolute restriction
on the file size, it means that the file can be saved to any device supported
by the 128. It is, of course, only possible to save one file per iteration of
this cycle. If many files are to be transferred, many boots and exits of CP/M
will be required. Construction of a boot disk for this purpose is advised.
The procedure:
1. Download a Packit-compressed file to a CP/M disk, using whatever
technique works best for you.
2. From CP/M, unpack the file. Command syntax is:
UNPIT -D ufn
Unpit does not accept ambigous file names. It does not support any query
of the contents of the .PIT file, nor any partial extractions. It will
attempt to extract all contents of the .PIT. Be sure your disk has enough
free space to permit this. If available, a 1581 is suggested.
The -D parameter will cause the program to extract only the "data fork" of
each file, and to not translate CRs to CR-LF pairs. The "resource fork" is of
no value to you.
3. C128LOAD a component file. The starting address will always be 1C00.
Note the ending address. Note also that, although these are Bank 1 addresses,
the program's author has chosen not to preface them with the Bank number.
4. Place a formatted C= disk, with no boot sector, in drive 8, and
CTRL-Enter out of CP/M. This procedure will not disturb the contents of the
area of memory used for the file, nor will it destroy the contents of the REU
CP/M disk, if used.
5. Press F8 to enter the MONITOR.
6. Save the file. If the starting address reported by C128LOAD was 1C00
and the ending address was 7A80, and the desired file name was MACPIC.DAT,
the command would be:
S "MACPIC.DAT",8,11B82,17A80
The reason for the unusual start address is as follows. UNPIT strips off
the 128-byte Macbinary header that the Mac->C= converters expect to find at the
beginning of a .BIN type Macpaint download. The address 11B82 is 126 bytes
before the start of the Macpaint data placed in memory by C128LOAD. Using the
MONITOR S function will cause the first two bytes of the saved file to be the
load address. These two bytes, plus the 126 bytes before the data, will
function as a garbage Macbinary header, which will be skipped by whatever
conversion program you are using.
7. Type X to exit the MONITOR.
8. Repeat steps 1 - 7 as needed.
9. Convert the files to your desired format.
10. I am unaware of any means of returning to CP/M from GEOS without
turning off the computer.
Ed Flinn - 09/11/88
revised - 03/30/89
revised for Mac Attack II - 11/13/89
minor revision - 03/25/90
addendum: For those with access to an MS-DOS machine.
Primarily for the use of VCO users, there are Unpackit and Unstuffit
utilities available for MS-DOS machines. To the best of my recollection, the
MS-DOS Unpackit utility does not strip the Macbinary header, so the file can be
processed as-is. The MS-DOS unStuffit utility produces a file with a different
header than the Unpack utilities. With the advent of Joe Buckley's Mac Attack
II, which supports two header sizes, it became practical to convert these to
geoPaint. This program also permits the conversion of geoPaint files _to_
Macpaint format.