UAE Support & Analyser Data View

17 March 2002

More talks with Toni about getting UAE to support CAPS images. Toni is thinking along the lines of making UAE support only one simple internal format that supports bit cell timing (and might be similar to the CAPS release format). Any type of floppy image format (CAPS, the various ADF formats, FDI, etc.) will then be converted to this form as they are loaded which will apparently reduce much of the current complexity. However, handling disk images with timing may cause unnecessary slow downs and greater memory requirements, if this is the case the the old internal MFM format will be kept for images that do not need density information.

Obviously this is all just talk at the moment and nothing has been started or is set in stone. We will know more once we are both closer to implementing things.

The internal format may also support multiple revolutions (samples) for the same track. The reason for this is that some disk protections actually expect magnetic noise to be read - i.e. different data read at each revolution on certain parts of a track. These noise tracks by their nature also have random cell timing, not just random data.

A few other bits that are likely to turn up in future WIP’s as they rely on implementation details which are yet to be worked out.

As we keep banging on about a “viewer for unmapped data after analysation” that still needs to be done, we might as well explain it since the work has been started this week.

Okay, remember that the analyser performs the automatic process for investigating disk formats and associates the parts with appropriate descriptors. One task that it does it to map all the blocks on the disk to a known block descriptor.

When we describe a disk format, every single block of data on that disk will have been documented - that is, what it is and what it is used for - the “data type” of the block if you like. Now, lets take early Psygnosis games as an example since a descriptor for those was recent added (see the 28th February 2002 WIP). Most of these games have the same or similar disk format. If we dump another Psygnosis game with exactly the same disk format, then there will be no unmapped blocks after analysation. The disk format descriptor will fit perfectly.

Now if we take another Psygnosis game that has a similar disk format to the one known, but not exactly the same - we will know that it has a slightly different disk structure as (apart from offending tracks not being marked as 100% verified) there will be unmapped blocks.

To aid reverse engineering of these unmapped blocks we needed to implement a way to look at this data. So now we are currently implementing the data view functionality for “uncharted” data (unmapped blocks), so the images can be easily checked by a human.