I haven't used my old 390X in the past 2 or 3 years. I decided this week to either sell it or make it useful. I ended up opting for the latter, by maxing the RAM to 512MB, replacing the HDD (Samsung Spinpoint M5 160GB), and installing XP SP3. That will take care of the major issues.

It once had two batteries, both of which died long ago and were dropped off at a recycling center a couple of years ago. However, this still leaves the issue of the gaping hole where a battery once was. (Having designed this so a 2nd battery can go in the UltraBay, I can't for the life of me understand why they didn't engineer the battery bay as an UltraBay.)

I could buy a 2nd-hand battery cheap on eBay, but would prefer something lighter. I don't really need or want a battery. It is dead weight, as I will use it strictly off external power. I could just leave the hole, but am concerned about a spider walking in and making a suicide pact with the PC. It also looks a bit broken with the hole in it. Anybody here know of a dummy filler made for that hole?

Other issues include:

Ethernet:
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The computer has a Xircom 10/100 network card bought around Y2K, whose chief virtue is the actual ethernet port is on a dongle whose connector to the card is as slim as the card. (Unlike the typical card I see today that sticks up an inch or so from the top of the PC) The main issue is it seems to be limited to 10 Mbits thruput. I don't know if the limiting factor is the device or the PC. Can I get faster ethernet to work on this box? The Xircom is fast enough for internet use, but on big file tranfers at home, it uses only 1% of my gigabit LAN. Surely, the 32 bit bus can handle 100Mbits. Or can it?

USB
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Is there any hope of adding full data rate USB 2.0 to the 390X? I have some Seagate FreeAgent Go drives. They require USB 2.0 at full power load. I am dead certain the 390X will not supply sufficient power, so I will certainly need to buy an independent-powered 2.0 hub. However, USB on the 390X is limited to a single USB 1.0 port. So, I am also looking at getting a PCMCIA card with USB 2.0 ports to plug the powered hub into. Anybody have experience with this, or a different solution than both a PCMCIA card and a separate powered hub?

The bottom line is, will the 390X move data fast enough for the Go drive?

One of my 390X units came from a scrapper. The previous owner had gutted the battery and left the shell installed so it looks stock but weighs much less (could tell when I picked it up before poking around).

Your best bet is to buy a dead battery on ebay for a few dollars and tear it open to remove the cells (recycle those).

160GB HD seems excessive, what do you plan on installing and running on that unit?

Wiki says:
"The speed of CardBus interfaces in 32-bit burst mode depends on the transfer type; in byte mode it is 33 MB/s, in word mode 66 MB/s, and in dword mode 132 MB/s." Speed also depends on if BUS mastering is used or not.

I plan to run XP. But, the prolog to your question requires a much longer explanation.

The fact is I generally buy the drive with the greatest capacity I can afford within my budget for that computer. Why I do that takes some understanding of computer performance in general, and HDD geometry in particular. (I have some professional expertise in both areas. I will spare you my lecture on the importance of the HDD to overall system performance. )

As your question suggests, it is unlikely I will use even one quarter of the space. The drive in question goes for $55 at NewEgg. It is a new drive, with a 3 year warranty. That amount was within my budget for upgrading the 390X.

The drive under consideration has a specified seek time of 12ms and latency of 5.6ms. If I could alternatively get a 40 gig drive for (say) $40, with identical seek time and latency, the question then comes down to whether an extra $15 is excessive. Or, maybe I could do a lot better by buying an old-tech used drive on eBay with the same specs?

Assuming a new drive, why throw away even $5 for space I will never use? That question is based on the assumption that the only thing that matters about HDD is space. Why pay extra for more space than you need? Indeed.

What many people fail to understand about large capacity drives is that they provide much more than capacity. In particular: The greater the capacity of a drive, the greater the recording density. The greater the density of a recording medium, the less time it takes to access a unit of information. IOW, capacity = performance. Seek times and latency are handy, but give a false impression to many. Drive capacity is super cheap today, which makes for very interesting performance equations.

Latency is simply the time for a half-rotation of the spindle, so is the same for all drives of a given number of RPMs. All 5400 RPM drives have a latency of 5.6 ms. I would not put a drive with greater RPMs in a laptop not specifically designed for it, because of vibration. So, 5.6ms latency is pretty much a given for the 390X. However, it is highly likely that the next unit of information you need immediately follows the last unit you read, so the greater the amount of information available the more data. Higher capacity drives have more data per rotation, hence, faster average access time. The 8MB cache on this drive improves that even further. Not to be had on older drives.

The specified seek time of a drive is not a constant like latency. It is based on using the entirety of the space reachable by the head. My guess is that most computer users have a system partition that comprises the entirety of the HDD, which makes these seek times reasonably accurate because Windows allocates space from both ends. However, I do not partition drives that way. What I will do with this drive is create a 12GB C partition on the outermost tracks of the drive. 12GB is more than enough to run XP and the apps I have in mind. If an average seek over the entirety of the drive is 12ms, what is the average seek time over 7.5% of the drive capacity? Not as easy a question to answer as it looks. Consider first that the arm will travel less distance than 7.5% of the drive surface because there is more information on the outer tracks of a drive than the inner tracks. (The circumference is greater) Second, you need to break down seek time into constituent parts to understand how much of the 12ms time is travel time, how much is just overcoming inertia, etc.. I haven't done the necessary testing to determine this precisely, but all in all, I would be surprised if seek times in the resulting partition exceed 2ms.

Bottom line: How much price differential would you consider "excessive" for a drive with 2ms seek time versus one with 12ms seek time? I could get a 250 GB for about $30 more, but that is about it. In this case, the Samsung seems to be at the "sweet spot" for my 390X, given my budget.

I was thinking more on the lines of what speed the built in IDE controller can do (the bottleneck is there), so I never bother with anything over 40GB for a Thinkpad that old and tend to use Win2k instead of XP.

Yea, I understand the price points of new drives, which is why I just get used drives (they are used laptops after all).