I have a Panny EH55 and when I put in a RAM disc it shows capacity as something like 4.37GB, when i use a DVD-R its capacity is listed as 4.40GB

Any idea as to why a RAM disc has ever so slightly less capacity than a -R?

any info would be greatly appreciated

Thanks in advance

Its just formatting. All discs technically have 4.7 GB capacity, but thats before taking into account reserved areas needed for DVD player compatibilty and/or rewritability. Eraseable or "VR" mode discs need to keep track of whats been added or erased, and various editing options not available on write-once discs, so they eat up a little extra capacity to do that. On my Pioneers, I can format write-once media to be editable using VR mode: after doing this I note the listed capacity drops from 4.4GB to 4.3GB, which indicates more flexibility eats up more disc capacity. In your comparison of RAM at 4.37 vs R at 4.40, the difference is almost negligible- don't worry about it.:)

Its just formatting. All discs technically have 4.7 GB capacity, but thats before taking into account reserved areas needed for DVD player compatibilty and/or rewritability.
Actually, the reason we can fit only 4.4 GB, of info on a "4.7 GB" disc is simply the difference in figuring capacity: disc mfgrs use the decimal numbering system based on K=1000, while our DVDRs (and computers) use the binary system based on K=1024.

The difference on a DVD is indeed negligible, but the bigger the drive, the bigger the difference. The new Seagate 1.5 TB HDD I just added to my HTPC shows up in Windows as 1.36 TB, a difference of 140 GB. Hey, six or seven years ago, I paid $400 for my first external HDD, which at 120 GB was less than the difference between the space advertised by manufacturers and the actual capacity on the Seagate. I think we should pay for storage capacity in binary dollars. "What, $150 for this drive? Here's $136. Bye."

Any idea as to why a RAM disc has ever so slightly less capacity than a -R?It's because RAM discs have "hard sectors". RAM disks are basically just like hard disks in that any sector can be read and re-written independently of the others. All of the other DVD disks (-R, +R, -RW, +RW) use a sequential recording format that requires a long, continuous stream of data for each "session" on the disk.

Each hard sector of a RAM disk requires a little bit of space - you can see them as a series of marks in a rather odd pattern when you look at light reflected off the disk. So that means there's a little less space available for the data.

Although the analogy isn't perfect (and I'm really dating myself here), anyone who remembers hard- vs. soft-sectored floppy disks will get an idea of the concept.