CDROM Writer General Info and Setup

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CDROM writer are very popular now. A good kit with CDROM writer, great software, and controller cards cost less than $370. Cadillac versions are under $1000. The big reason for the popularity surge is simple enough: media is cheap. Premium quality media is less than $1.65 with a jewel case. At that price CDROM media looks great for everything from making custom music CDs to backing up the hard drive's critical files.

What hardware and software to you need? The real questions is,"What do you want to do with it?"

Most of the hardware is SCSI based, although some of the newer units are IDE. SCSI has the advantage that is has the ability or potential to do its job without loading the PC. More importantly, it can do its job without being affected by the PC's other tasks. This fact can be critical.

When making or copying a CD, you might have to transfer over 600MB of data without a single error. You only get one chance, since most drives and media are write once. If you have a standard CDROM burner, it writes at 2x and reads at 6x. This is the 2x/6x designation. At 2x speed, even an audio CD would still take 30 minutes to copy. Even simple mouse movements during this time can upset the data transfer buffers in WIN95. Don't even think of launching Word or Excel. The extra I/O traffic is too much for IDE or simple SCSI controllers. You make a mistake -- you get a Frisbee. It is that simple.

The Smart and Friendly kit, SAF777, contains a 2x/6x writer, the Adaptec suite of duplication software, and a 15xx ISA based SCSI card. this kit sells for $355. The drive is currently a JVC product. Older units were made by Sony. Although they do give you a SCSI controller, it is ISA based, and it doesn't do bus mastering. It is not a good choice for audio or high speed data transfers. A PCI controller, such as the Adaptec 2910 or 2940, are much better choices.  Some of the new Plextor CDROMs are now bundled with PCI controllers. Plextor makes two main CD writer kits, the PX-R820TI and the PX-R412TI. Both can be purchased with the PCI controller option in either internal or external units. These are considerably faster and cleaner for audio work than anything else on the market.

The 2910 can't control hard drives, but it does and excellent job with tape drive, JAZ, scanners, and CDROMs. It's half the cost of a 2940UW at $100, does bus mastering, and is PCI PnP. This means that the MB's BIOS will auto detect the card and its settings.  It will get an IRQ assigned, and then WIN95 will load the necessary drivers. This processes is completely automatic.

Free SCSI cards belong in the junk box

The 15xx (AHA-1505, 1510, 1520) card that comes with the SAF kits is legacy ISA. It is also pretty cheesy. It has no rear output connector.( Heck, some don't even have and end plate bracket! This makes it worthless for driving a scanner, for example.) Legacy means that you must MANUALLY set the card jumpers. It is not PnP. Then you have to get into the PCI BIOS and block that IRQ out from the other cards. The PCI PnP manager doesn't even see legacy cards. The ISA card is also slow and can't buffer much of the load of the CD writing session. It isn't worth the time to put it in the box. It is very poor for audio CDROM copying. It does work, but you can't even breathe on the PC while burning a CD. Buy a 2910 or 2940 and be done with it.

In either case, you might have to do some system IRQ management when adding a SCSI controller. Interrupts are a precious resource in a busy PC. Please check the IRQ map page on this site for help. It is not trivial!

Audio CD Copying

If you use the burner for data CDs, backing up files from your PC's HD for example, you can use the kit as is. If you want to make CD audio copies, however, then you have to pick the correct CDROM as the player ( source ).

Most of the newer IDE and SCSI CDROMs will pump the digital audio data into the data bus. That doesn't mean that they do it well or quickly.

The Toshiba 6000 series IDE CDROMs are very popular. They range from 16x to 24 or even 32x data speeds. They only play back audio at 1x, 150KB/sec. The NEC IDE units will play back at 10x, but the data isn't synchronized properly. You get 1.5MB/sec of garbage. In general, IDE CDs are not good choices for audio.A lot of the CDROM copy programs won't even run without a SCSI source and a SCSI writer. This is especially true of the old versions of EZ CD Creator. Because of bus loading issues, poor playback audio speeds, and the fact that you will not have enough IRQs left to run an IDE and SCSI CDROM in your PC, the source should be SCSI. Even SCSI CDROMs, however, are not created equally.

Loading the PC's bus and CPU

To make a CD up to 650MB of data must be pushed from one source to the CD writer. Whether it comes from another CDROM, the HD, or a via a network card, this is still a lot of data. ( Incidentally, a floppy drive can't read fast enough for CD writers to work properly. So don't even try to add info from a floppy directly. Copy it to your HD first and read it from that location. ) While the CD writes the data stream can't be disrupted, at least not for very long.

All systems have some disturbances, however. Even if you don't launch a huge, new application, the mouse gets moved or a screen saver might kick in, for example. Some setups can't even take the extra load of a screen saver. This is especially true of IDE CDROM writers because the IDE controller can't multitask. It is standard procedure to disable all screen savers while burning CDs. These programs do take a lot of CPU cycles to keep complex, changing shapes whizzing around your screen. The CPU needs to spend time managing the data write cycles not making pictures on the CRT.

Most CD writing software will either ask the user to disable or will automatically disable WIN95's Auto Insert Notification. By default, Microsoft scans all CDROMs every few seconds to see if a new CD has been inserted. This is nice for day to day data CD installation, but it takes a few seconds for the insert scan to complete. If the system buffer runs out of new bits for the writer in that time, your new CD will turn into a Frisbee. 

A good, SCSI, CD burner with a good, SCSI controller is the best way to minimize CPU and bus loading effects on the CD write cycle. The key word here is good. As mentioned earlier ISA based SCSI cards are better than a sharp stick in the eye but not by much. ISA cards are only 16 bits wide at 8MHz at best. PCI will retrieve data at 33MHz with 32bit words. That is an 8:1 difference in just the bus interface. Good SCSI controllers offer the one feature that is essential for making reliable CDs: an onboard CPU.

SCSI itself isn't anything magical. Only recently has Ultra Wide, 16 bit, SCSI become popular. Standard Ultra SCSI is only 20MB/sec with an 8 bit bus. UDMA33 IDE HDs have burst rates higher than that by quite a margin and sustained rates nearly as high. What makes it work faster under load is the ability to multitask. To do that function a SCSI card must offload work from the PC's main CPU. This is where the term Bus Mastering controller comes from. A Bus Mastered SCSI card, a 2910 or 2940 for example, takes only basic instructions from the PC. On older SCSI controllers you could actually see the 80186 or 80286 chip on the controller. Now the CPU is in the custom ASIC and is not visible. The card itself does the heavy work, minimizing the load to the rest of the PC. Conversely, while an IDE devices reads or writes, the PC can't do much until the drive finishes.

A benchmark test on 32X CDROMs proved interesting. The test used a PII 350 PC on WIN98 with 128MB of RAM. The test was to see the effects of CPU loading. The IDE CD was a Toshiba 32x model 6302. The other CDROM was a Plextor 32x, SCSI, model PX-32TSI with an Adaptec 2910 controller. Under 100% CPU availability, both drives read at 32x, just as the manufacturer claimed. But what happens at only 60% CPU availability? 60% of a PII 350 is still a lot of CPU. The Plextor was still running close to 32x. The IDE Toshiba was now under 10x, however. By 40% the IDE CDROM is almost dead at 2.5x. IDE can't multitask.

Part of the IDE CDROM's loading problem has to do with the size of the buffer. IDE drives, even good ones, are designed to be low cost. The designers save some money by using small amounts of cache buffer RAM in the drive. Car stereo CD players use large amounts to eliminate skips and jumps in the music. A 10 second audio buffer is very common. The standard PC, IDE drive only has 256K of cache, however. That is 1.4 seconds of audio data or 0.7 seconds of a 2x data copy session. It isn't much. The UltraPlex. 32X has 1MB, four times the amount. The 4x and 8x Plextor writers use 2MB. With the large cache buffer, a small system wink doesn't correspond to a bad CD. The software has plenty of time to catch up and repair any bad data.

If a the PC has a 2910 or 2940 controller, SCSI CDROMs are much better and reduced bus loading than IDE. The Toshiba 6201B, a 32X SCSI unit, makes flawless audio CD copies when used with the SAF777 kit. Yet, it still copies audio at 1X. This is over 1 hour for a full audio CD. Ick! NEC makes a few SCSI CDROM players that only work at 1x with an audio CD. I tried one 8x SCSI, NEC unit. I made several audio CDs. Some of them had a second or two of repeating audio at the beginning of tracks. It sounds just like a record skipping. It is annoying at best. The best solution so far is the Plextor CDROM family. They also make 4x/12x and 8x/20x writer kits. These are higher end than the Smart and Friendly kits.

Plextor makes a 12x-20x, and a new 32X SCSI CDROM, the UltraPlex. The UltraPlex. is the first CDROM player to support Ultra SCSI, 20MB/sec burst rates. The drive's true transfer rate is a maximum of 32 x 150KB/sec =  4.8MB/sec. Still this number is huge compared to other CDROM players, and it will not melt as the CPU load increases -- the true joy of SCSI bases hardware.

All of the Plextor drives have a large internal cache buffer, excellent mechanics, and will play back digital audio at over 10x perfectly for all models. Audio and data playback is flawless. You will not hear any skipping on your audio tracks. They are not cheap, but they are the perfect choice for audio work. The prices are as follows:

PX-20TSI $139 12x to 20X Internal tray
PX-32TSI $149 14/32X UltraPlex., Int tray
PX-32TSE/PCI $309 14/32X UltraPlex. EXT. w/PCI controller, cables
PX-32TSE $229 14/32X UltraPlex. EXT. no controller
PX-32TSI/PCI $235 14/32X UltraPlex., Int tray w/PCI controller
PX-R820TI/PCI $568 8x Writer/20x read SCSI w/PCI controller
PX-R820TE/PCI $630 8x Writer/20x read SCSI EXT. w/PCI control
PX-R412CE/PCI $555 4x Writer/12X read SCSI EXT. w/PCI control
PX-R412CI/PCI $490 4x Writer/12X read SCSI Int w/ PCI controller

A Toshiba 12X SCSI 5701B is $100. This is a little cheaper than even the 20TSI Plextor. If you want to do audio work, however, the Plextor is drive of choice.

Buying a unit with a controller isn't such a bad idea, but it's really the same cost delta as a separate Adaptec 2910 or 2940U unit. Certainly it would be better for the external unit, since you get an expensive SCSI, external cable for free. You know the cables will fit, too! Although, only buy one with a PCI controller. The ISA controller is cheaper but much too slow for serious work.

The Plextor UltraPlex. kits sold with SCSI controllers ( /PCI in the part number ) use the Adaptec 2940AU PCI model which does support hard disk BIOS. Ultra SCSI controllers, with good drives, will do 20Mb/sec burst rate. It is identical to the 2940UW without the WIDE SCSI interface. This is a very nice PCI SCSI controller, oodles better than the ISA models shipped with most CDROM writer kits. This is an excellent match for any quality, SCSI, CDROM system and comes with wonderful software.

The Plextor 8x writers are about $75 more than the 4x kits. An 8x writer can burn an entire 60 minute audio or data CD in less than eight minutes. If your company has a lot CDs to make, a 4x or 8x burner can pay for itself rather quickly over a 2x kit .

Make sure you use the Adaptec drivers instead of the default WIN95 set. Otherwise your SCSI controller will not function properly.

11/27/98

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