Sun microystem hard disk EIDE & IDE

EIDE is Enhanced IDE.

It was the first boost in IDE drive file transfer speed.

The sequence of revisions went:
IDE
EIDE
UDMA
UDMA 33
UDMA / ATA 66
ATA 100
ATA 133

Generally, things are backwards compatible.
However, many older motherboards cannot recognize the newer large capacity hard drives.

The best work-around for this is a PCI IDE controller card. These sel for around $30, and provide large drive support along with the faster file transfer speed of the new drives.

Sometimes, installing an older drive as a slave with a newer drive will cause the entire IDE channel to run at the data rate of the slowest drive.

Chas

I've an existing Sun system motherboard running on an EIDE disk.Is it possible to put in second IDE drive as a slave.
pls advise
thks

When I visited our Fujitsu (Sun's partner) main service department some years ago for harddrive replacement, their engineer told me that Fujitsu doesn't recommend to put an older IDE harddrive on the same controller/machine with a newer EIDE hard disk(s).
It's OK for temporary connection just for copy purpose though, he added.

You can use any disk that supports Ultra DMA Mode 1 (33mb/s) in a Sun Ultra-based IDE workstation. The Solaris 7 (and above) uata driver negotiates multi-word direct memory access with the IDE controller and targets (disks). Older IDE disks (pre-1995) that do not support multi-word DMA are not recommended. PIO, or programmed I/O, imposes a substantial CPU overhead on a system, as the processor must facilitate each interrupt that is raised by the disk controller (usually 2 or 4 bytes at a time.) DMA allows the processor to queue up a large read/write and have the I/O controller place the data into memory. (It can literally take hundreds of interrupts.)

Yes, any UDMA hard disk has backward compatibility, and it is possible to use any newer UDMA hard disk instead of any obsolete disk, unless large hard drive support problem arises on some of old machines. The newer the disk - the better. Especially if we take into account that the price for the newest IDE disks is not to high. And if you find somebody sells old obsolete disk(s), don’t be surprised: the price would be incredibly high for the unit of space! And I think that the original poster knows very well without our help that it is good to have a new hardware.

But the original question is about the difference between two particular types of PIO-mode drives: EIDE and its direct predecessor – the original IDE, andwhether it is possible to install those two types together on a machine (why to by new if we can use old for some purpose, say for study?) . And it looks like there is a not-new machine, two old hard disks, and there is a question related to that hardware, not about buying a newer UDMA drive.

The answer is: it is possible to install both types of disks, the configuration is workable, but not always recommended though.

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