Sony MINIDISC manual Quick Random Access, Reprogramming the Order of Music

A: Before RearrangingMusic Data and Order are Recorded Area-Wise

Disc Signal Lead in UTOC Only Music Data is Recorded

UTOC Data TNO START STOP

1 A B

2 C D

3 E F

4 G H

B: After Rearranging (No Change of Music Data) Connecting two Tracks:

Rearranged Area

What it is and How it Works

Quick Random Access

Reprogramming the Order of Music

1.	Ordinary Method:
A: Before Rearranging			Music Data and Order are Recorded Time-Wise
	Inner Edge	A	B C	D E	F G		H		Outer Edge
	Disc Signal	Lead in	1	2	3	4		Lead out
B: After Rearranging
		Lead in	1		2	3		Lead out
					Rearranged Area
2.	MiniDisc:

Lead out

	Lead in	UTOC		Only Music Data is Recorded			Lead out
			UTOC Data	TNO	START	STOP
				1	A	D
				2	E	F
				3	G	H
Additional Reprogramming the Order:				TNO	START	STOP
				1	A	D
				2	G	H
				3	E	F

The ease of quick random access was made possi- ble by the development of the Compact Disc (CD). The CD instantaneously provides random access to the beginning of any desired music selection. After using a CD player, the time to reach the music sel- ection of your choice with cassette tape players seems extremely cumbersome.

The MiniDisc provides the same high-speed random access for recordable discs as well as for premaste- red discs. In addition, the recordable MiniDisc has a circumferential microgroove or ”pre-groove”, which is formed when the polycarbonate substrate is injec- tion molded. This pre-groove is the basis for the tracking servo and spindle servo operation during recording or playback.

Address information is recorded at intervals of 13.3 milliseconds using a technology that places infinite- simal zigzags on this pre-groove. Therefore, the disc has all the addresses already notched along the groove even with no recording. The result is a

stable and quick random access, as well as a variety of optional features, including programming of the playback sequence e.g.: rearranging the sequence of the titles recorded on the MD without rerecording of the music information in a matter of seconds.

This is possible because of the “User TOC Area”, located around the inner edge of the microgroove, which only contains the order of the music. This system is similar to the “directory management system” of floppy discs. In other words, starting and ending addresses for all music tracks recorded on the disc are stored in this area, enabling easy programming just by rewriting the addresses. This supports also other features: it is possible to erase a track out of a sequence and during playback no gap in the remaining music will be heard. The era- sed segment is allocated to the free space – it is possible to record a piece of music independent of the number of segments used.

DADC 5

A U S T R I A