Vanishing hard drives

[Amiga_Always]

Here's a puzzler for you!

I recently revived my old a1200 and powered it up to find the hard drive made some very odd noises and refused to boot. I changed the drive for a cf adapter I had with 4gb card, booted from floppy, partitioned the drive fine, rebooted and no partitions came up to format. Tried this 3 times, then tried a real hard drive, same thing. I've changed the cable and power supply in desparation with no joy.

Any ideas anyone?

[Phantom]

Ensure that your hard drive is being recognised by the A1200 at the Early Startup-Mouse (by holding both mouse buttons at startup). Also what program do you use? I suppose the original HDToolBox what came with Workbench? Does this recognises your hard drive?

[Amiga_Always]

No sign of it in Early Startup, yet HD Toolbox sees it no problem. I have set up tons of drives in the past so I'm pretty sure it's not me. Are thrre any other partitioning tools you recommend?

[Phantom]

Try HDInstTools from Aminet. Easy to acquire. I never had problems with HDToolBox, as it's my prefered method instead of HDInstTools (while it seems and feels better allowing big partitions, actually it's not as it seems), but try with that if you have success.

[Amiga_Always]

Solved it! My CD drive was causing the problem, as soon as I disconnect it I can boot to the hard drive no problems, just need to get another CD drive now! Thanks for the suggestions, it's good to know there is someone out there! :D

[Harrison]

Was the cd drive also on the same internal idea port? if so, the port can only run one device unless you add a buffered ide interface, and even with that you need to use the software idefix before you can use the HDD and cd together.

[Amiga_Always]

Ide ports have 2 channels, master and slave, so can run either 2 hard drives or 1 hd and 1 cd on the same cable as long as it's a reasonably short one!

I've been playing around with the cables a little more and got both to work together again, only strange thing is the hard drive (master) is on the slave plug on the cable and vice versa, it won't work at all the other way round, wierd but true!

[Harrison]

Not in the A1200 and A600 they don't. The A1200's internal IDE port is a single channel unbuffered IDE interface and will only directly support 1 drive/device as a master and does not support a slave drive. Commodore only ever intended this port to be used for a single internal 2.5" IDE HDD, so cut costs by doing this. You need to use a buffered IDE interface connected to this port to reliably use more than one drive at a time. You can buy one from Amigakit for about £11.

[Amiga_Always]

I'm not going to argue with you over this, me being new and all, but I currently have a 40Gb HDD and CD-RW running from the internal port of an A1200 Rev1B using a 44pin to 2 x 40pin cable with no problems. What you are saying could well be correct under OS 3.0, but not for 3.9 which I am now running!

[Phantom]

I'm not going to argue with you over this, me being new and all, but I currently have a 40Gb HDD and CD-RW running from the internal port of an A1200 Rev1B using a 44pin to 2 x 40pin cable with no problems. What you are saying could well be correct under OS 3.0, but not for 3.9 which I am now running!

I understand you, as I used to use my A1200 with exactly the same cable 10 years ago, using the A1200 internal IDE, so I had my 3.5" HD together with a CD-ROM back then working without any problems AND I was running AmigaOS 3.0!!! Of course to take it into account I had to use a program (I don't recall its name now).

[Harrison]

OK, let me try to explain it a little better.

Yes the A1200's internal IDE port can theoretically support 2 devices, just like any other IDE port, but it is non-buffered and only supports PIO 0 mode. POI mode requires that every byte of data transferred between the disk and the CPU must be sent through the CPU's IO port bus (not the memory), and so it uses a huge amount of CPU resources to access any IDE devices in this mode, and as the A1200's port is unbuffered it doesn't have any way to cache data during this process so the A1200's CPU has to dedicate all its CPU time to HDD access when requested, which slows everything else to a halt whilst doing this.

By added a buffered IDE interface to the A1200's internal IDE port it provides the much needed buffer to avoid this problem, and also allows drives to run in DMA mode, which allows for drives to read and write data directly between the drive and the ram, and no longer requiring all data to need to be sent through the CPU's IO port bus. This therefore stops the CPU needing to dedicate many CPU resources at all to this process, so it can continue processing other tasks instead.

Therefore it is highly recommended not to try to run 2 drives from a standard A1200 internal IDE port as you will just slow the system down to a halt every time the OS tries to access the drives. And it is worse with a CD drive because of the volume of data it needs to read from the CD when accessing it, which is why CD drives can suddenly vanish from the system when trying to run them with such a setup. Running a CD drive in DMA mode instead avoids this problem completely and stops the drive crashing or locking the system up whilst accessing the drive.

You can test this out on a PC if you have an IDE CD or DVD drive connected. In windows switch the IDE mode being used by the drive from UltraDMA to PIO and reboot the system. After rebooting insert a CD into the drive and watch the system's CPU usage shoot up to 100% and the system slow right down whilst it accesses the drive. Switch it back to UltraDMA and reboot and insert the CD again and the CPU will now show hardly any increase in CPU usage, maybe 2-5% at most, and the system will remain responsive and usable. This is because in PIO mode it is having to dedicate CPU time to transferring all data from the drive, but in DMA mode it is now directly transferring it to ram and bypassing the CPU.

I hope that makes sense and explains it a bit better?

I think the program Phantom is remembering was one of the CD device systems needed to be able to access a CD-rom drive on the Amiga. Many of these added their own software IDE modes to try and emulate DMA and buffered cache modes to try and get better performance out of the system and let the drives work better without dedicated software.

IDEFix'97 is currently still the best software to utilise if you wish to add a CD/DVD drive to an Amiga IMO as it has the best CD drivers I've tried.

[Phantom]

Yes Dave, IDEFix was that program (although unregistered back in the those days, but still done its job well).