This is done by copying the contents of track 34 (at byte offset 156672) from one disk image to the other. While pillaging the Ballyhoo image, also copy over the boot track code. two tracks, eighteen 256-byte sectors each) from one disk image to the other:ĭd if=ballyhoo.dsk of=newgame.dsk conv=notrunc bs=1 count=9216 This is done by copying the first 9216 bytes (i.e. Next, copy the Z machine interpreter from Ballyhoo to the new disk image. So, let's start by using the Toolshed decb command to create a clean disk image called "newgame.dsk": Starting here, I will presume that you have a "version 3" Z machine story file available called "newgame.z3" and an image of the original Infocom Ballyhoo diskette called "ballyhoo.dsk". more features and fewer bugs) causes me to select to use the "COCO VERSION D" interpreter taken from the Ballyhoo disk image. My personal preference for starting via the DOS command and my (baseless?) presumption that higher versions are later and hopefully better (i.e. The "VERSION A" interpreters are not started via the DOS command, but instead require either the standard "LOADM : EXEC" combo or a BASIC program to do the same. Given the above, a decision must be made as to which interpreter version to use. If you get different results than shown in the table above, then _PLEASE_ let me know in the comments below or however else you may know to reach me! If you have an original Infocom game disk for the CoCo, please boot it up and issue the "$VERSION" command. Were the CoCo versions released in a different order than the original game release order? Or perhaps the diskettes imaged on the Color Computer Archive were purchased in random order over a period of time, while the diskettes sold were sent with whatever version of the CoCo Z machine interpreter was current at the time? Was a version "B" ever released? What about a version "E" or other later version? Also, if we relate the alphabetical version order to the original release dates of the games above, the release order of the games does not seem to match the version order for the CoCo Z machine interpreters. Oddly enough, no interpreter found reported anything like "VERSION B". As shown in the table below, at least three interpreter versions were shown to be used by Infocom to package their games for the CoCo! After starting each game, I issued the $VERSION command in order to collect version information from each interpreter. I loaded each of the Infocom games from the disk images at the Color Computer Archive. Care must be taken to preserve the contents of track 34 if use of the DOS command is required to start the game. The DOS command loads data from track 34 of the disk into a fixed location in memory, checks for a simple signature at the head of that data, and then jumps into the loaded program if the proper signature is found. Many CoCo games (including some versions of the Infocom Z interpreter) depend on being started by the DOS command in DECB. However, at least some versions of the Infocom Z interpreter rely on being loaded via LOADM and therefore require a valid directory to be present on track 17 of the disk image. how programs are started), a valid directory may not be required. The Disk Extended Color BASIC (DECB) code on the CoCo reserves track 17 of the disk for storing the disk's directory. This simple, sequential data layout makes reading and writing specific track data by offset into the disk image very simple. In its simplest form, this format is merely a sequential arrangement of sector data arranged sequentially by track, yielding a 161280 byte file representing a single-sided disk with 35 tracks, 18 sectors per track, and 256 bytes per sector. This post will focus on producing what is known as a " JVC" diskette image. Choosing and following the appropriate process for any of the above will be left as an exercise or the reader. The resulting image can be used as-is in MAME or another emulator, it can be loaded on a real CoCo with a CoCoSDC device or using DriveWire, or it can be used to write an actual physical diskette. The outcome of this whole process will be to build a diskette image. In this post, I intend to tie-up some loose ends and to detail the actual process involved. In the previous posts in this series, I have discussed pairing original Infocom Z interpreter software with new Z code story files in order to enable new interactive fiction games to run on the CoCo.
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