 The magazine of the Melbourne PC User Group NEC CDR-74 CD-ROM Reader Ash Nallawalla ash@melbpc.org.au |
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NEC is well-known for its range of electronics products. Most of us are familiar with the MultiSync range of monitors; some of us use NEC PCs or laptops; so it is no surprise that NEC has been making CD-ROM readers (drives) for some time. I took a look at the CDR-74, a desktop device that is powered from the 240 vac mains but its operational features are shared by an internal model called the CDR-84, which fits in an accessible half-height bay inside your PC.
Description
The CDR 74 can be mounted flat or on its side. It is a SCSI (Small Systems Computer Interface) device. I used the NEC SCSI interface kit, which is a rebadged Trantor unit, but I could have used some others instead. SCSI in simple terms gives you the ability to connect up to seven SCSI devices in a daisy chain manner while taking up only one slot in the PC. Other SCSI devices can be tape drives, hard drives or more CD-ROM readers. Note that other brand SCSI interface cards may not come with the requisite driver software.
It is one of the fastest readers on the market, with a 280 millisecond access time (others are at the 800 millisecond end), 300 kB data transfer rate, and a 64 kB cache. The data transfer rate is achieved by NEC's 'MuitiSpin' technology. It comes with a manual, cartridge ('caddy'), and a vertical mounting kit. The literature claims that it is MPC compliant for multimedia applications and is 'XA-ready.' The reader is compatible with IBM or clone PCs, ATs and Macintosh.
The MultiSpin features let the disc spin at variable speeds depending on the type of data being read and the amount of error correction needed. At most times it spins at twice the usual speed. It becomes noticeable with large, multimedia flies, which are buffered better than previous models, which used to give choppy animation.
Cautions
Installing any CD-ROM reader can cause some a problem, not confined to this brand or model. You may have to detune your PC to make the reader compatible. Some PCs will not be compatible at Turbo settings. With Dos 5.0 you will need to exclude the SCSI card's memory space from the memory manager. Some non-standard 16-bit video cards might need to run in their 8-bit mode. Some PCs might need to have their shadow RAM and all caching disabled. I didn't have any such problem with the CD-ROM reader but it helped to solve another. (I found I had left my bus mouse jumpers at the wrong setting.) A minor inconvenience is that if the reader is not switched on then the PC's boot up sequence is paused until I press the Enter key.
In Use Installing the SCSI adapter card was very easy. The Microsoft CD extensions (MSCDEX) and the NEC driver were the latest, so I had no problems with them. The reader has an additional dust flap so you need two hands to insert a CD-ROM. The three controls are on the front panel, which is another plus.
The reader became Drive "E" on my PC because my last drive was "D". Other than that it is accessed just like a conventional disk. You can use all non-destructive DOS disk commands with it. For example, you can use Norton Desktop and browse through its contents; install CorelDRAW! from it; run a knowledge base on it using some components that lie on your hard disk, and the like.
Reading Photo-CDs
Kodak offers a service where one can take ones slides and negatives to a bureau and have them transferred to a special CD-ROM called a Photo-CD. I don't have one to test but on Usenet there have been a few messages claiming that the CDR-74 will not read them. Some of these people had existing, non-NEC SCSI cards and the problem seems to lie there. The Adaptec 1542B card is one of these.
Then there have been replies pointing out that the CDR-74 will indeed read Photo-CDs. Some users who had the
CorelSCSI card said that the /XA switch in its driver must be set. A person from the Philips
Consumer Electronics headquarters in Eindhoven, Holland gave a definitive answer. the problem really lies with Microsoft's
MSCDEX (the CD-ROM extensions for DOS). It does not have XA capabilities yet Readers will need to have firmware
changes - it is not a hardware problem - to read multisession CD-ROMs.
He added, "The CDR-74 indeed is a single session device. It can read multisession (multivolume, or hybrid) discs, but only the first validated ('fixated') session. I tried reading blocks beyond the first lead-out area on a multisession CD (written by the Philips
CDD 521) and it wouldn't do that The problem is that a Photo-CD is a CD-ROM-XA. A
CD-ROM-XA contains mode 2 blocks instead of mode 1 blocks as on normal yellow-book
CD-ROMs. The NEC CDR-74 (I use a CDR-84, an internal version of the CDR 74) can read mode 2 blocks ('raw blocks') and I wrote a program to read the directory of a
Photo-CD, talking directly to the device driver, i.e. bypassing MSCDEX. That worked perfectly. The problem is
MSCDEX, which doesn't support CD-ROM-XA discs, asks for mode 1 blocks and runs amok when getting error messages from the device driver when it finds mode 2 blocks."
Plays Audio CDs Too
You may wonder why one would want audio CD playing facilities on a CD-ROM drive. So did I, until I
tried it. The CDR-74 has a headphone socket and volume control on the front panel and a
DOS-based Music Box utility that gives you the same controls that a CD player does. A set of stereo earphones is supplied.
My PC is not near my conventional CD player, so my CDs rarely get used. Music Box can be run in memory-resident mode, so I now listen to CDs while I type away. The audio is quite clean and loud enough for me. You may prefer to hook up a stereo amplifier to the CDR-74 through the audio jacks provided on the rear panel.
Availability
The NEC CDR-74 has a RRP of $1169 and the SM Interface Kit retails for $263. The CDR-84 is $1054 and the CDR-37 is $768. Street prices are usually lower and/or you often get a few
CD-ROMs thrown in.
Conclusion
The NEC CDR-74 reader is a fast, well-engineered, reliable device. I have used it for a month at this point with no problems. Several PC Update
personalities have the same or related NEC readers and they have not reported any problems with them either. You pay a bit more for a fast reader,
particularly if you intend to play with multimedia. The cheaper, slower drives might be fine for installing software onto your hard disk but they are quite a pain for using software that needs to access the
CD-ROM frequently. I recommend the CDR-74 to you.
Reprinted from the December 1992 issue of PC Update, the magazine of Melbourne PC User Group, Australia
