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Old Motherboard - Memory Device

L

lycurgus

Member
I'm looking at a friend's ancient Compaq machine. It's a 486/66 and the mobo only has one socket for a floppy (3.5" and / or 5.25") and one for a harddrive. Is there anyway to install a CD-ROM on this machine? BTW, my friend likes to put together and run 'old junk', so there's no point in suggesting 'get something more modern'.
 
Well, I suppose as long as the hard-drive is set to master and the CD-ROM drive to slave it should work on the same IDE channel (BIOS support depending). I doubt you will get bootable CD ability though.
An alternative would be to get your hands on an old IDE controller card (ISA or PCI depending on what the board has) and plug the CD drive into that, although that would require more boot-time drivers in DOS to possibly get the card working then the normal CD-ROM driver.
 
Thanks for your reply. The card idea is probably not an option. The challenge here is to put something together with the old 'junk' that's available. I'd also be concerned about trying to get it to actually work on that machine. I did install a cable and tried to install the CD-ROM as a slave to the harddrive. When I tried to get Windows (95A) to 'detect newly installed hardware', it didn't see the CD-ROM, even as an unrecognized device. Of course Compaq has that weird pseudo BIOS - O/S program that runs underneath the O/S, so perhaps I needed to 'add' it there first. Also, the CD-ROM was set to slave, but the pins on the back of the harddrive (which is also ancient) were a different configuration from what I'm used to. First there were only 4 pins (instead of the usual 6) and there was no label (SL, MA, CS) as there usually is. Also, the jumper was connecting two pins 'horizontally' rather than the normal veritical. I assume it was already set to 'master', since it was the only device on that channel.
 
As I recall, you will probably need to load DOS CD-ROM drivers before Win95 will "see" a newer ATAPI drive. Try booting from a Win98se boot disk, the generic drivers should work fine, and you can then copy them from that disk to the compaq, and edit the config.sys and autoexec.bat files to load them with the Win95 version of MSCDEX.
 
Thanks for the info. But do you think that I'll have to do something first in the pseudo BIOS program to 'add' the CD-ROM before trying to install it in DOS or Windows?
 
It's hard to say. It may effect the operation of the drive in DOS, but Windows 95 and onwards should scan the IDE bus independant of what the BIOS says is there. Either way it can't hurt, but an old BIOS may not recognise the drive and have an entry for it.
 
OK, thanks again for the help guys. Do you think the age of the CD-ROM matters? Would there be an issue with recognizing a more current CD-ROM, whereas an older might be recognized? Or if it recognizes one CD-ROM should it recognize any CD-ROM?
 
Well, technically if it recognises an old CD-ROM drive, it should recognise just about any. Whether this works in practice is another matter altogether.
 
Very probably the system's BIOS won't know what a CDROM is. But that doesn't keep DOS or Windows drivers from using it anyway - just prepare yourself for PIO mode 0 ...
 
Could you elaborate on your comments Peter. Do you mean that, even if a CD-ROM works the data transfer will be really slow? In that case is there any point in installing anything other than a minimal speed unit (e.g. 2X)? I appreciate any info you can provide.
 
PIO modes are not by definition super slow. There are 4 PIO modes:

PIO Mode 0: The fastest data transfer rate reaches 3.3Mbyte/sec
PIO Mode 1: The fastest data transfer rate reaches 5.2Mbyte/sec
PIO Mode 2: The fastest data transfer rate reaches 8.3Mbyte/sec
PIO Mode 3: The fastest data transfer rate reaches 11.1Mbyte/sec
PIO Mode 4: The fastest data transfer rate reaches 16.6Mbyte/sec

PIO mode 0 will be the minimum it supports, but I actually would think its possible that the machine may support something like Mode 2. Anyway, even if PIO mode 0 is the fastest available that is still enough bandwidth for about a 20x unit.
The biggest problem with PIO mode transfers is what makes Ultra DMA modes so good to have..... the amount of CPU usage is usually far higher with PIO mode.
 
I have had problems with win98 boot disk recognizing older cd-rom drives before.
I used a newer cd-drive to get the OS loaded and then let the OS find the old drive.
www.bootdisk.com has some stuff you might could use.

Good advice from the people above.😀



🙂
 
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