USB Flash Disk on DOS – July 01, 2008

No, you aren't reading the Internet Wayback Machine - this is 2008, and the National Institute of Mental Health still uses DOS for testing subjects.  (If it isn't broken, don't fix it...  And they can be much closer to real-time accuracy with DOS rather than Windows.)  However, as the data sets get larger, and floppy drives become increasingly less common, it is harder and harder to get the data off of their testing machines back to the experimenters' desktops to analyze the data.

This is where Lime Daley comes in - using FTDI's VDRIVE chip, we created DOS applications that could talk to the chip via the serial port.  Due to the limitations of serial buffer sizes, and a design flaw in the vinculum chip, the speeds aren't that great (FIFOs have to be turned off in some instances) though a baud rate of 115200 is achievable on most systems.

It was a fun project, starting with dusting off our 6.22 install 3.5" floppies and popping them into a VMWare install on a Linux machine.  (Any of you remember installing MSDOS 6.22 and being excited about the DriveSpace or new memory managers that it came with?  Or maybe you were cooler than that, and had already been using third-party tools like DoubleSpace and QEMM...  Don't forget to set your STACKS variable in the config.sys if you are going to be doing heavier work.)  Once we were taking over the keyboard and ctrl-C interrupt handlers, VMWare wasn't so happy, so we had to dual boot to DOS fairly often.

Look for this project in the May 2009 issue of Circuit Cellar.