Howard’s Blog

I recently bought a SanDisk Cruiser Micro USB Flash Drive. On the package, it mentioned that it was U3 Enabled. When I plugged the drive into my PC running Windows XP, it immediately (and without warning or prompting) came up as two drives (a “CD-ROM” drive, and the regular Removable Disk Drive that I was expecting) and installed the U3 Software on my system.

I was a bit skeptical about this. I don’t necessarily want this software on every PC I plug the USB Drive into, and the time it takes to install on a new machine makes it a pain to use. After reading a bit about U3, I decided that I did not want this functionality, and luckily was able to find a U3 Removal Tool which removed this software from the USB Drive. The removal process is irreversable, but for my purposes, this is fine. It should also be noted that the removal process erases the entire USB Flash Drive, so it’s best to do this before you put data on it.

Additionally, I wanted to format the Flash Drive with the NTFS filesystem. I was unable to do this through the regular Disk Management tools under Windows, even after I changed the hardware properties to “Optimize for speed.” In the end, I found out that I had to use the “CONVERT.EXE” tool, included with Windows, which can be run from the command line as follows:

C:\> CONVERT drive : /FS:NTFS

Now the drive works well, and since it’s formatted with NTFS, I need to go to the “Safely Remove Hardware” taskbar icon to dismount the drive before unplugging it. For me, the added features and performance of NTFS and write caching make this extra step worthwhile. I just wish Microsoft Windows would allow dismounting a volume even if it thinks it is in use, or at least tell me what program is still accessing the volume. Sometimes I have to log out of Windows to get the drive to dismount cleanly.

-Howard

Recently, I was wondering how different the various released versions of CP/M were, relative to each other. I was wondering if CP/M evolved in an organized fashion, or if each release was put together in a haphazard way. I’ve looked at various parts of CP/M source code from The Unofficial CP/M Web Site and I got the feeling, from looking at the contents of each archive, at separate times, that these were “snapshots” of someone’s development directory.

In order to trace the evolution of CP/M-80, I started with the CP/M-80 2.0 sources, and checked them into a fresh Subversion repository. Next, I made a Tag for the CP/M 2.0 sources, so that I could easily return back to those files in the future. Then, I put the CP/M 2.2 sources in my Subversion workspace, and did a file-by-file ‘diff’ comparison using the TortoiseSVN client for Windows. Then, on files that matched between CP/M 2.0 and 2.2, I reverted the workspace copy back to the CP/M 2.0 copy, so that when I checked the CP/M 2.2 files in, I would only update the changed files. I repeated this process for the CP/M 3.0, and for the CP/M 3.0 with Y2K fixes and DRI patches applied. What I ended up with was a history of CP/M-80 from v2.0 through 3.0 (Y2K), and it is interesting to trace the history of CP/M this way, and see how the operating system evolved.

For your hacking enjoyment, I’m providing a ZIP’d copy of the CP/M Subversion Repository (1.25MB) as well as the version of the Subversion for Windows that I used (3.18MB) to create this Repository, and the TortoiseSVN for Windows (7.43MB) that I used.

If you install TortoiseSVN and Subversion (may require a reboot,) and then download and un-ZIP the CP/M Subversion Repository (1.25MB) , and then use the TortoiseSVN extensions to Windows Explorer to browse the repository. This makes seeing the difference between versions of CP/M much easier. In addition, tags are provided for each release of CP/M from 2.0 to 3.0 (Y2K).

I was not able to find much in the way of source for CP/M 1.4, but it would be very interesting to see how CP/M evolved from 1.4 to 2.0. It appears that from 2.0 to 2.2, the primary changes were bugfixes. From 2.2 to 3.0, many new utilities were added. I did do a binary comparison between some of the .COM files provided with CP/M 1.4 and CP/M 2.2, and it appears that a lot changed.

I will leave it as an exercise to the reader, and a challenge to CP/M enthusiasts, to dig up the 1.4 code (or disassemble it based on the binaries, and use the code from 2.0 to try to reconstruct the source as closely as possible.) If more of the CP/M 1.4 source is found, I’d greatly appreciate if this code would be made public, and posted on the The Unofficial CP/M Web Site.

Another interesting exercise would be to try and see where MP/M-I and MP/M-II branched from CP/M, and what files are common between them.

-Howard