Frame buffer and hard disk follow-up.

I investigated a couple of interesting things hardware wise yesterday that may be of interest.

Frame buffer

Frame buffer

Firstly I tried out the Sun Wildcat Expert3d lite frame buffer card I got during this week. To my surprise it does indeed work with my systems, in fact it seems to be hardware compatible with both of them.  For those who haven’t read my earlier posts, I have two more “recent” Sun machines, a Sun Fire R280 and a Sun Fire V440. I tried the frame buffer card in both machines and the ROM not only recognised the cards but displayed boot messages on the screen.

I don’t have any Sun keyboards or mice for either machine so I wondered if I could use a standard HID compliant PC keyboard and mouse. This also surprisingly worked quite well both systems recognised the keyboard as being connected as long as you plugged it into port 0 (the left most bottom connector looking at the back). I wondered what issue people were having with these machines, I didn’t wonder long.

I found the software support for the Wildcat frame buffer was where I would be let down. FreeBSD on the R280 didn’t use the text console at all despite the ROM and boot loader using it happily. After installing X I was informed there was no console device, which was a bummer! So rather than fiddling around to see if I could make FreeBSD co-operate I decided to try Gentoo Linux I have installed on the V440.

The V440 and Gentoo are much happier with the card it seems, I get a nice 125 line text console that I can interact with! I’m in the process of installing Xorg now, and am hopeful of getting basic functionality, but think getting any kind of accelleration out of the card unlikely.

The other thing I investigated actually comes from a few weeks back, when I took photos of my old hard disk drives. I was wondering which ones were working (if at all) and decided to test my older SCSI hard disks.



Most of the drives functioned perfectly, which was _very_ surprising! I was able to read the data on them and even found some of the drives had previously been in old Sun Systems as they had Sun partition tables on them. So I backed up what I thought useful.

One drive however was faulty, one of the Quantum ProDrive LPS drives. I found out those drives are actually 250MB instead of the 200 I thought them to be. This one made some funny unhealthy noises, and couldn’t be recognised by the SCSI card, so I figured it was dead beyond any feasible use. I took it appart and took some photos as a record.

Circuit Board

Circuit Board

The circuit board isn’t really anything to write home about, it has an assortment of Quantum ASIC chips and some other devices. Interestingly there is a chip marked AT&T that I think may be the disk read data processor, which is a chip dedicated to coding/decoding data from the heads and servo control (datasheet). The board also appears to carry some RAM for caching disk data.



Inside we see an optical system for positioning the heads, hard disk manufacturers later moved to putting data on one side of a platter for positioning the heads. This is an earlier system used mostly by quantum as far as I know. Also note in the voice coil motor the rubber stops that would be much the same as those described by Goughlui on the original post for this drive. The rubber in these appears to be intact.

If you look closely at the top platter you can see why the disk failed, it appears to have grooves across the upper surface indicating a possible head crash or bit of dirt in the drive. This drive has two platters with 4 heads in total.



Here is a close-up of the optical positioning system, the clear plastic has tiny markings on it, this helps position the heads. The controller observes the movement in this plastic by looking for pulses on a very narrow beam of light. Note the trim pot in the background, I wonder who or how they calibrated that!

Upper surface

Upper surface

Here’s a closer shot of the upper surface showing the markings that indicate failure. These disk surfaces should look just like a mirror, this one clearly has had a grove cut into it by either the heads or some dirt caught on them. It could have been just a spec of dust!

I took a few more photos but they didn’t really turn out focus wise. My digital camera is an old Canon IXUS 95 IS which was good when I bought it about 6 years ago, but is showing it’s age in the photos it takes. Perhaps it’s just me with bad technique.

1 Response to “Frame buffer and hard disk follow-up.”

  1. 1 goughlui
    November 3, 2013 at 3:55 pm

    Thanks for the post! Very nice to see the optical + voice coil motor set-up that I so very rarely encounter (last time I did, I didn’t get a shot of it). It’s hard to get good disk shots – reflections wreak havoc with focus and flash. Still, a great effort and very lovely to see :).

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