Compro 7503 8W/20R CD-R - Page 2

Here's a list of the features found in the Compro 7503 8W/20R CD-R drive.

  1. 8x Speed Writing and 20x Speed Reading CD Recorder
  2. Capable of Reading, Writing & Decoding and Encoding Error Correction Code in real time through SCSI interface
  3. 2MB built-in data buffer
  4. Support CD TEXT reading & writing
  5. SCSI-2 Interface
  6. Major CD-ROM formats are supported


Item Specifications
Interface SCSI-2
Media CDR - Orange Book Part II
Data Capacity 656MB(mode 1)
748MB(mode 2)
Record/Read Speed Writing (CD-R):
1X speed (real-time), 2x speed, 4x speed, 8x speed
Playback: 8 - 20X speed [Max] (partial CAV)
Data Transfer Rate 20xS: 3000KB/sec
8xS: 1200KB/sec
4xS: 600KB/sec
2xS: 300KB/sec
1xS: 150KB/sec
Burst Transfer Rate 10.0MB/sec (record asynchronous, Max)
5.0MB/sec (read asynchronous, Max)
Data Buffer Size 2MB
Loading Tray
Audio Out
(Normal Speed)
Frequency range: 20~20,000Hz (Line Out)
Output Level 0.6Vrms (Line Out)
Dimensions 146 x 41.3 x 203mm
Weight 1 kg
Writing Methods CD Audio , CD-ROM (mode 1 & mode 2), CD-ROM XA (mode 2, Form 1 & Form 2) CD-I (mode 2, Form 1 & Form 2) CD-I Bridge, CD-I Ready, CD-Extra, Photo CD (single & multi-session), CD-G CD-TEXT
Supported Format CD Audio , CD-ROM (mode 1 & mode 2), CD-ROM XA (mode 2, Form 1 & Form 2) CD-I (mode 2, Form 1 & Form 2) CD-I Bridge, CD-I Ready, CD-Extra, Photo CD (single & multi-session), CD-WO (fixed and variable packets) CD-RW CD-G, CD-TEXT

Wait A Minute, What Does 8/20 Mean?
The Compro 8/20 actually means the drive has a 8X Write capability and a 20X Read capability (normal CD-ROM drives are at least 32X nowadays). You will find this quite a standard naming convention across other CD-R drives. You may have encountered other notations e.g. the Yamaha 6416S. Now, this simply means the Yamaha drive is a CD-RW, supporting a 6X Write, a 4X ReWriteable and 16X Read. Simple huh?

How Fast Is 1X?
1X is actually equivalent to 150 KBytes/s. We know that a normal CD can hold 74 minutes of audio CD or roughly 650 MB of data. By applying simple arithmetic, we can deduce how long a 1X drive takes to burn a disc and how fast a 8X drive is in comparison.

Record Speed Record Time (mins)
1X 74
2X 37
4X 18.5
6X 12.3
8X 9.25

From the chart above, we can see that if we are to burn at 1X, it will take 74 minutes to copy a CD! Fortunately, with the advances in technology, we are currently enjoying speeds like 4X and 8X on our CD-R drives. 

However, I would like to point out that burning at high speeds like 8X requires not only a drive capable of doing it, but also high quality CD-R media. Most CD-R media in the market today only allows you to burn reliably at speeds like 4X and 6X. You will need to scout around for special CD-R media in order to support 8X.

Buffer Overruns
By now, you should have heard about the dreaded phrase, "Buffer Overruns". Why we get this error is simple. In a CD-R drive, once the laser is initiated, data must be consistently streamed down from the source drive to the CD-R drive. The reason is simple. The laser will continue to write (until terminated by a "switch-off-laser" command) regardless of whether there is data in the buffer. 

So what happens when your source drive is unable to feed enough data to your CD-R drive? Well, you get a buffer overrun and your CD-R disc will become what we affectionally call a "coaster" (Thus termed because it can now be used as a coaster for your coffee cups).

With a 8X drive, it's important to note that your source drive needs to be at least capable of performing a read of 1,200 KB/s. As a rule of thumb, your source drive needs to be able to read at least 3 times the writing speed of the CD-R drive (i.e. for a 8X CD-R drive, you need at least a 24X drive as your source).

To prevent buffer overruns, most CD-R drives come with an internal buffer. The Compro 7503 comes with a 2MB buffer to prevent buffer overruns. Personally, I find the 2MB a little too close for comfort. For a 8X drive, 4MB of buffer is recommended. At a rate of 1,200 KB/s (8X), it will only take a mere 2 seconds before the 2MB buffer runs out. At 4X, it allows a greater level of tolerance and will take roughly 4 seconds before the buffer overruns. 


So, what's in the package?

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