How about option #4, a dedicated CD-ROM ISA card because the controller is so weird? 😁

My Philips / LMSI CM-205 and LMSI CM-250 ISA card to run it. (I'm still salty about throwing away my Mitsumi LU005S 1x-speed drive 20+ years ago, but this is pretty cool as a stand-in)

For a more serious answer, it depends entirely on the PC it's installed in. Primary IDE is always a bad idea because the hard drive and CD-ROM sharing one cable never goes well which I'm sure we all found out the hard way long ago.

2nd controller is really the best option for Pentium or late 486 motherboards that support it and is the best option in most cases.

The sound card option is one of those things that was important for a brief time in the 90s and then not long after. Specifically 386/486 PCs usually had an ISA / VLB super I/O with just one IDE channel because why bother with two? Then along comes CD-ROM and now we need both, but most controllers or motherboards only have one channel (386 > 486 DX2-66 era) so soundcards come along and provide the proprietary controller for the CD-ROM drive. Not long after that, CD-ROM drives moved to being IDE / ATAPI only and the extra IDE provided by the soundcard wasn't around for too long after that.
It's really fun to set up a soundcard and proprietary CD-ROM that has to be run through the sound-card's CD-ROM connector though 😀 I think the most fun I had setting up an old PC was getting the Panasonic / Matsushita CR-563-B going on my SoundBlaster 16. Not exactly quick, but definitely enjoyable to see it all working.

Hatta wrote on 2023-11-30, 00:16:

Primary IDE slave, 2nd IDE master, or sound card?

Does it matter?

It does not really matter - as long as it is not on the sound card.
However, the newest drives like 80 pin wires.
Basically I prefer secondary master.

Thermalwrong wrote on 2023-11-30, 00:29:

How about option #4, a dedicated CD-ROM ISA card because the controller is so weird? :D LMSI - CM205 Drive & CM250 Card.JPG My P […]
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How about option #4, a dedicated CD-ROM ISA card because the controller is so weird? 😁
LMSI - CM205 Drive & CM250 Card.JPG
My Philips / LMSI CM-205 and LMSI CM-250 ISA card to run it. (I'm still salty about throwing away my Mitsumi LU005S 1x-speed drive 20+ years ago, but this is pretty cool as a stand-in)

For a more serious answer, it depends entirely on the PC it's installed in. Primary IDE is always a bad idea because the hard drive and CD-ROM sharing one cable never goes well which I'm sure we all found out the hard way long ago.

2nd controller is really the best option for Pentium or late 486 motherboards that support it and is the best option in most cases.

The sound card option is one of those things that was important for a brief time in the 90s and then not long after. Specifically 386/486 PCs usually had an ISA / VLB super I/O with just one IDE channel because why bother with two? Then along comes CD-ROM and now we need both, but most controllers or motherboards only have one channel (386 > 486 DX2-66 era) so soundcards come along and provide the proprietary controller for the CD-ROM drive. Not long after that, CD-ROM drives moved to being IDE / ATAPI only and the extra IDE provided by the soundcard wasn't around for too long after that.
It's really fun to set up a soundcard and proprietary CD-ROM that has to be run through the sound-card's CD-ROM connector though 😀 I think the most fun I had setting up an old PC was getting the Panasonic / Matsushita CR-563-B going on my SoundBlaster 16. Not exactly quick, but definitely enjoyable to see it all working.

SCSI controller, of course. This avoids lame PIO transfers, as long as you don't have a non-DMA HBA turtle.
But the dedicated controller of the first Mitsumis supported DMA transfer, whether the controllers on the sound card did not!
Sound card would have been an option when you have had 2 hard drives on your only IDE channel, like in 286, 386 and old 486 PCs.

It depends on what works. I have a 486 with one IDE port on the motherboard (ATAPI drives don't work with it). I use a sound card's IDE connector for two ATAPI drives.

On my Pentium MMX computer, I use the secondary controller for two ATAPI drives.

On my Core i7-2600k, I actually use both of the SATA3 ports (mapped as the Primary IDE Master and Slave in the BIOS) for my optical drives. Those ports work better with internal drives (short cables) than the external SSD's I use for my experimental builds. The software I use doesn't care.

Im guessing we are limiting ourselves to ATAPI CD-ROM drives.

I have one thats set up on the only ATA connector that is set as the master because the hard disk is SAS. I have another set as the secondary master because its an OEM system thats set up to be like that.
Otherwise if using a "normal" motherboard with 2 ATA connectors then I would probably set it as the secondary master, but it space is a problem then the primary slave.

Hatta wrote on 2023-11-30, 00:16:

Primary IDE slave, 2nd IDE master, or sound card?

Does it matter?

Depends on the CDROM model. Need more info. If IDE / ATAPI still need more info....

A single IDE CDROM drive? Secondary Master or Slave (depending on other devices on the bus).

Multiple drives where one could be source and one used to write an image of the source? One on each channel regardless of master/slave.

On certain systems, I sometimes saw reduced transfer speeds when copying files from the CD-ROM to the hard disk if both were on the same IDE channel.

For example, HDD = Primary Master and CD-ROM = Primary Slave resulted in slow transfer speeds. In contrast, HDD = Primary Master and CD-ROM = Secondary Slave produced much faster transfer speeds. IIRC, this mostly happened on VIA chipsets.

I seem to remember that when you have multiple devices on an IDE controller, the transfer speed is restricted to the speed of the slowest device? So if you have a HDD and a CD-ROM on the same controller then your HDD speed will suffer... I think. So on that basis, HDD on one controller, CD-ROM on another.

Secondary master or the sound card. If it's just temporary for testing, I might have it primary slave, but those are strictly "desktop" builds. As in bare on the top of the desk, not in a case.

i have 2 kt133a systems:

system 1
primary master (no slave): udma100 compact flash
secondary master (no slave): udma66 16x dvd
tertiary master (no slave): udma100 7200rpm hdd raid
quaternary master (no slave): udma100 7200rpm hdd raid

system 2
primary master: udma66 16x dvd
primary slave: udma100 7200rpm hdd software raid
secondary master: udma133 7200rpm hdd
srcondary slave: udma100 7200rpm hdd software raid

counter-intuitively, the 2nd system has more even performance than the first. no issues with dvdrom placement in either case.

Back in the day when I burnt CDs this was a really important question. One of the reasons for choosing a CUBX motherboard with ATA-66 controller was so I could make every device single drive/master on a controller, my HDD on the ATA-66, my burner on primary chipset channel, my fast reliable CDRom drive (TEAC iirc) on secondary chipset channel. With this setup I could (fairly) reliably copy from CD to CD, although an upgrade from Win98SE to 2k helped even more. This came after trying to do something similar on my old P60 with CMD IDE controller running Win3.1 and an old version of Nero. Safe to say that never worked, I could only burn from HDD.

These days on retro builds it's all less critical. I hardly use optical media in any event, so the optical drives in my builds are mainly for cosmetics and filling holes in front of cases. Similarly, storage is less of a thing; depending on age of build, CF/DOM/SSD is relatively large vs software I'm running so generally only have one and do all my storage remotely (all systems XT and up are networked and have FTP servers). I do hook up the opticals though, either on secondary master or if I only have one IDE channel, primary slave. Or SCSI if I have SCSI. And I'm going to add my Matsushita/Panasonic proprietary drive to one of my systems one day, possibly from sound card, but I also have the dedicated ISA interface card.

Just like the others mentioned, I put the CD drive into the secondary IDE channel as master in my retro computer. The ones found on sound cards should only be used if the motherboard lacks IDE ports onboard.

I normally have SCSI in my build up to early Pentium, and then its on the SCSI bus.

For newer systems with IDE I put it on the secondary IDE channel as master.

Sounds like secondary IDE master is the clear favorite if it's available. What if it's not?

Thermalwrong wrote on 2023-11-30, 00:29:

Primary IDE is always a bad idea because the hard drive and CD-ROM sharing one cable never goes well which

Disruptor wrote on 2023-11-30, 00:46:

It does not really matter - as long as it is not on the sound card.

Given the choice between primary slave and soundcard IDE, which works better?

dionb wrote on 2023-11-30, 13:12:

I hardly use optical media in any event, so the optical drives in my builds are mainly for cosmetics and filling holes in front of cases.

What do you do for mixed mode games with CD audio? This was pretty popular in the 486 era before codecs were practical. I'm still out here burning CDs.

Secondary master. My Compaqs stock configuration I believe is the cd and floppy on secondary with the hdd on primary, so it must have been the common choice. If all you have is primary then it’s probably fine to do hdd master and cd slave, it just potentially might have the issues listed above, but its probably mostly fine.

Hatta wrote on 2023-11-30, 18:56:

[...]

What do you do for mixed mode games with CD audio? This was pretty popular in the 486 era before codecs were practical. I'm still out here burning CDs.

Tbh, I don't play any. If I did, they would go in that drive. I may put them in mainly for cosmetics, but I make sure they are fully functional just in case.

*Somewhere* I should still have a pile of (original) Wing Commander III CDs which would fall into that category (well, FMV rather than pure audio). But until I find that lost treasure, the CD drives don't do much more than occasionally boot an old version of Knoppix I use to test some hardware (badblocks works so much better for me than Scandisk/chkdsk).

Hatta wrote on 2023-11-30, 18:56:

Disruptor wrote on 2023-11-30, 00:46:

It does not really matter - as long as it is not on the sound card.

Given the choice between primary slave and soundcard IDE, which works better?

Depends on the speed of the CDROM.
You should note that I don't know any soundcard with an IDE port that supports UDMA.
So you should draw the line somewhere at 8x speed.

Basically you want to limit the times 2 devices are using the same IDE Channel.
Most of my builds I'm booting off spinning rust but all my games are installed on a HDD on the Primary IDE of the 2nd IDE channel.
Therefore it makes sense to put the CD drive as a slave on IDE 1

Hatta wrote on 2023-11-30, 18:56:

Sounds like secondary IDE master is the clear favorite if it's available. What if it's not?
Given the choice between primary slave and soundcard IDE, which works better?

I Never use the Sound card IDE port if at all possible, only in some 286/386 configurations when I have no choice.
What motherboard are you using ? What sound card ? What controller ? How many HD's are in this system ?
Vogons (Gibbs) rule #2, always give as much info as possible to aide in getting the best answers 😀