Partial-Response Maximum-Likelihood - this is a method of examining data in the context of its neighbors (in time) and comparing the sequence to those that are possible and selecting the one which is "most likely" based on the coding scheme used (this - of course - is a very short "arm waving" explanation at best).
Partial Response Maximum Likelihood: a technique used to differentiate a valid signal from noise which achieves improved accuracy by looking at entire waveforms rather than just peaks in isolation, using digital signal processing (DSP) to reconstruct recorded data. On magnetic disks PRML uses RLL encoding to provide a ratio of user data to recorded data of 8:9.
A read channel using sampled data, active equalization and Veterbi detection to accurately retrieve the user data off the disk.
Partial-response, maximum likelihood - advanced technology read channel that contributes to a faster data throughput rate.
Partial Response, Maximum Likelihood - technology is used in the read channel of DVD media controller chips.
In data storage, Partial Response Maximum Likelihood (PRML) is a method for converting the weak analog signal from the head of a magnetic disk drive into a digital signal. PRML attempts to correctly interpret even small changes in the analog signal, whereas peak detection relies on fixed thresholds. Because PRML can correctly decode a weaker signal it allows higher density recording.