Thursday, September 10, 2009

Comcast Internet: save yourself $10/month on a modem

(Original post 10 Feb 2009) It's simple.

Buy your own cable modem. Here's a list of sanctioned Comcast cable modems and another similar list of approved cable modems for Comcast. These URLs were hard for me to find from the main comcast site.

Hunt around and you can find one for $20-$40, which beats paying $10/month or so. I used Craig's list and got one for $20 (the guy was asking $15 but all I had was a $20 bill). I got a Thomson (RCA) DCM425. Works great. Has several blinky lights. Got this back in Feb 2009.

I should really pick up a second one in case the first one dies.

In fact, I told this tactic to the Comcast service guy setting up our connection and even he was paying the monthly rental for his modem. After our little talk, he was going to rectify that situation immediately. The guy's not an idiot. Huzzzah.

(Update: 07 Sep 2009) My RCA modem died suddenly on me the other night. I thought it was a Comcast outage but the next morning when it was still out I called Camcast and after a bit of reseting the line and power cycling at my end, we decided it was likely a bad modem. To my chagrin, I discovered, I really miss being connected. So we rented a modem from Comcast (a new Motorola SB5120) and sure nuff, it was bad modem. That night I couldn't get the rental modem to actually connect without going through some dubious download of McAfee software so I called Comcast back up and the woman said "I don't know why they (the earlier Comcast rep) don't tell you (the customer) that you have to call back when you get your new modem". After a bit of trial and error we finally got it working.

The moral was:
  1. Power cycle the modem with it unconnected to any ethernet but with it connected to the cable. Wait for it to get a connection.
  2. Hook up your router or computer to the modem.
  3. Go from there. And be careful your brower isn't serving a cached page if you get something unexpected.
The following day I hunted down another modem on craigslist and went down to Santa Clara to pick it up. Seems like prices have gone up as this was $40 (for a Moto SB5120 too) and this was the lowest price around.

I'll hook this up sometime when we can afford to not have internet so we can return the rental unit.

Thursday, May 28, 2009

Low-end DSLRs: Canon XT Rebel versus Nikon D40

If you are considering moving up to a low-end digital SLR, but are not really sure, the choice often boils down to the big two, namely Canon and Nikon.

I use my dSLR as a glorified point-and-shoot. I don't fiddle too much with aperature or shutter priority. I just want to get good photos of things happening around me quickly and not miss out. The one area I push my camera is low-light since I prefer not to use a flash if possible. So I'm often adjusting the ISO.

Another of my quirks is I don't baby my dSLR. After all it is only a $400 item these days, and so long as you don't abuse it, it will last. Over the last 4+ years ....
  • I always leave it on (which seems to not use any power, though people who borrow my camera are always turning it off, which annoys me when I then try to take a picture).
  • I never use my lens cap. I have put on a UV filter protector, but that has never been broken or even scratched.
  • I just throw it in my backpack or luggage. I don't have a camera bag since I just have that one lens.
  • I've never had any problems with
If you are a higher-end photographer who needs to take very-high resolution shots for blowing up bigger than 2' x 3', spend lots of time tweaking photos afterwards, are a professional photos, or simply want to have a better camera than a low-end dSLR, then skip this post.

Back in 2006, I had had a Canon Rebel XT for a few years, but wanted to try the Nikon D40. So I gave away my Canon as a holiday gift and got the D40 with the kit lens and an SB400 flash ($120). Both cameras came with a 18-55mm f/3.5-5.6 kit lens, non-IS. How do they compare?

Nikon advantages (most important to least)
  1. External flash for $120. The cheapest from Canon is around $220. Being able to bounce the flash is a huge win, as you can get pretty decent looking photos whereas before you have a semi-ghastly look. Also an external flash has its own AA batteries so it recharges faster and doesn't drain the camera batteries. This is a huge gain, and I would take a D40 + SB400 over any other $1000 dSRL w/o a flash. The first $120 I'd pay is for this Nikon flash, over any lens.
  2. Better folder naming/numbering. The D40 lets me name the suffix of the current folder on the flash card using any 6 letters I want so I can name things like "July4" or "Home" or "SFTrip". I don't offload my photos very often, say once every 2-4 months, and its super annoying to have a numeric ordering.
  3. Much better LCD screen, mostly because the Rebel XT screen sucks. But this is not very important anymore because the newer Canons all have much better screens, though apparently not as bright as the Nikons.
  4. Able to focus quickly more often. Every so often, both cameras would not focus, perhaps due to not enough light or not enough contrast. The Nikon seemed to do this a bit less than the Canon.
  5. Lens feel. Of the 3 Canon Rebel XT kit lenses I've played with (I was giving these away as gifts), only 1 had silky zoom feel. Pverall, I'd give the three Canon kit lenses an A, B+ and a B-. The Nikon kit lens has a A- feel.
Canon advantages.
  1. Faster, sharper focusing. The Canon snaps into focus so fast most of the time it seems like should jerk the camera. The Nikon in contrast is downright slow, though still much faster than point-and-shoot. Note both have trouble if there not enough contrast, e.g. if in a moving car, and the camera is partially aimed at the sky.
  2. Better access to the controls I care about, namely ISO, and resolution. The Canon has one-button access to both of these important fns. The Nikon only let me have a single programmable "Fn" control, for which I chose ISO.
  3. Ever so slightly better image quality, it being 8MP versus 6MP... but really this was very minor.
Other than that they were comparable. Battery life. Weight. Feel. Ruggedness. Lens optic quality.

In short, the fact that Nikon had a good cheap flash was the tie breaker. You can't go wrong with either camera. As of mid 2009, the Nikon D40 is available for under $450, making it hard to pass up. For another concurring opinion about the beauty of a D40, see Ken Rockwell's site.

Were I buying today, I'd probably get the D40 again or wait until a model that took video was under $650. Note too that so far video taken by dSLR cameras is not that great; a good camcorder does better job. I'd really like a full-frame camera with an FX sensor, instead of the DX sensor on lower end dSLRs, but full-frame costs much more at $2500+ and are much heavier. And people would probably laugh at me if I used some crappy kit lens with a full-framer.

Wednesday, May 27, 2009

Automatic login and file vault in Mac OS X

If you cannot enable "automatic login" for a user in Mac OS X Leopard or Tiger, make sure that user is not using FileVault. Although no documentation seems to indicate this will cause problems, it makes sense that auto-login and FileVault conflict.

The purpose of FileVault is to leave a user's files encrypted so if the laptop is stolen, the contents remain unreadable. To read a FileVault directory, you need the login password. However if auto-login is enable for that user, then the laptop will automatically apply that user's password, offering decrypted access to all the files, hence defeating the purpose of FileVault.

My wife found out the hard way, know as trial and error and lots of internet searching, to figure out why she was not getting the option to enable auto-login on her account on her Leopard laptop. Her login was simply missing from the menu of choices for auto-login. It was only after stumbling upon a web page alluding to this issue for Tiger that she thought to try disabling FileVault. Apparently FileVault and auto login were much closer together in the UI for Tiger than they are in Leopard, where now they are in separate System Preferences.

In any case, mystery solved.

Monday, May 25, 2009

Fixing iTunes to get CD track names info once again

On a MacBookPro, iTunes suddenly stopped being to download the track information on a CD I wanted to rip, giving the error "Unable to connect tothe CDDB server". I have iTunes setup so that when I insert a CD, it automatically rips it and then ejects it. Only now it could not get the CD or track info. I had ripped hundreds of CDs (my own of course). ITunes was reasonably upto date at version 8.0.2.

It wasn't the network connection.

Doing a google search, leads one to possibly try an update to the gracenote software, as gracenote is the company that runs the CDDB information service. But the update was for windows, not Mac OS.

And it turned out to be my firewall settings. You have to let iTunes "share" its information. Turn this on via: System Preferenes | Sharing | Firewall | iTunes Music Sharing.

Sunday, February 8, 2009

Who stole my MacBook wifi card?

After upgrading to the latest Leopard release 10.5.6, my wifi connection wouldn't work. Hitting "turn ON" did nothing.

So I rebooted.

And now, the machine states "no airport card". Gah!

A quick Google search showed that resetting your NVRAM (or PRAM) is a solution that usually works. The first time I only hit restart and might have held the keys down too long and that did not work. The next time I shut down and then held the P, R, command and option keys down for exactly two chimes. That did the trick.

Friday, January 16, 2009

Adventures with Netflix and the postal service

Here are some of the incidents I've had with Netflix and the postal system:

Netflix's fault: I almost always mail 2 DVDs back in the same envelope. This saves them on postage since I use half the number of envelopes. On a few occasions, they indicated they got disk A but not disk B. This is one of the few cases where I know their computers or scanners messed up. They clearly got them both, but missed one. In every case, later that day or the next day they noticed disk B. I assume the scan-in missed disk B but on the scan-out to the next customer they notice the disk and realize it had been returned.

On several occasions I've had disks not arrive on time. I usually wait 3 extra days. It arrives about half the time, but the other half it never arrives. Netflix is really good and has never given me any hassle about lost disks. Probably because they are a small percentage of all my rentals.

I try to rent movies the moment they are released, before the masses realize it.
The most recent snafu was when I got all but one disk on the expected date. Several of the envelopes were partially torn. And of course, the one disk I didn't get was the one I wanted most. I was hoping the disk would arrive the next day, but instead I got mail from Netflix indicating they had received this back from me! Ack. So I've put it back on my queue and probably won't get it for another 6-8 weeks.

And finally, despite the tone of this post, a big shout out to the US Postal Service. I know empirically over 95% of all the Netflix mailings get to me and also get returned in 1 day. It's really first class service.

Friday, January 2, 2009

Linux and the Nvidia GeForce 6050/7050 IGP - getting rid of the X11 flicker

The goal was a new dual core machine that would be quiet and cheap. Oh I like to have 4G of ECC RAM, too.

So, I installed Ubuntu 8.04 AMD64 many months ago and all went. Almost. It recognized the 4G of ECC RAM. In fact everything was perfect except that when I started up X11, the screen would flicker randomly every few seconds. It's a brief tearing as if there is memory contention (recall that an integrated graphics chipset shares main memory with the rest of the system). It made the system unusable. My hardware is an Asus Socket 939 M/B using the Nvidia GeForce 6050/430 chipset; AMD Athlon 64 X 2 3800+, Kingston unbuffered ECC DDR2 PC4200 RAM, Seagate HDD.

I found that Slackware 12.1 which is based on a 32 bit kernel would not recognize any more than 3G of RAM, though it didn't have the flickering. But I didn't install 4GB to only get 3GB. And besides, I was trying to move away from the big Slack.

Back to Ubuntu....I tried the latest Nvidia drivers of which there are many and not labeled in any coherent fashion. I tried reconfiguring X11 fifteen different ways, I tried searching on Google and LKML, I tried looking at header files and everything I could think of. Eventually I just gave up and let that machine sit. And sit.

It's now 8+ months later and as a Christmas project, I installed Ubuntu 8.10 and again all goes well except the screen still flickers. Not as much but it's still there.

Hunting through the internet, somebody finally nails the problem down for me. In a post not on what caused the problem. Thank you, thank you.

When the CPU changes clock speed, the screen flickers.

The recent Ubuntu releases make use of CPU governors, which dictate if/when the CPU changes speed. The dynamic freq governors, which slow down the CPU when there isn't much load and speed it up when there is are "ondemand", and "conservative". The default is "ondemand". AMD desktop CPUs seem to have the following 3 frequencies they can run at: nominal (max performance), 1.8GHz and 1.00 GHz.

So I changed the governor to "powersave" which simply runs at the slowest speed all the time. (If you know anything about CPU performance, you typically don't lose that much normal performance by halving the speed .. say around 30-35%, unless you are doing CPU intensive computations like floating point). And I get a cooler CPU. On a second system based on the BE-2300 (45W) Athlon X2 3800, the CPU heatsink is barely warm running at the slowest frequency.

How to do this


# As root
% cpufreq-selector -g powersave

# As an administrator
% sudo cpufreq-selector -g powersave


To see the available and current both governors and cpu speed look in /sys/devices/system/cpu/cpu0/cpufreq/

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
powersave

% ls /sys/devices/system/cpu/cpu0/cpufreq/
affected_cpus related_cpus scaling_governor
cpuinfo_cur_freq scaling_available_frequencies scaling_max_freq
cpuinfo_max_freq scaling_available_governors scaling_min_freq
cpuinfo_min_freq scaling_cur_freq scaling_setspeed
ondemand scaling_driver stats

$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
userspace ondemand powersave conservative performance