Station wagon full of tapes vs cigarette pack (was Re: thinking of the "ultimate" retro x86 PCs - what bits to seek/keep)

Swift Griggs swiftgriggs at
Fri Jun 3 15:21:45 CDT 2016

On Fri, 3 Jun 2016, Mike Stein wrote:
> How many station wagons full of 9-track tapes would fit into a (20) 
> cigarette box filled with microSD cards?

Station wagon full of tapes = 51 GB
Pack of stogies full of SD  = 2816 GB

It's not fair using 9-track tapes, but let's go with it.

Let's consider the Ford Focus SE station wagon which has 95.7 cubic feet 
of passenger space and 35.2 cubic feet in the back with all the seats up. 
So, that's 130.9 ft^2 total.  We'll keep the seats up so we can use them 
as pillars to strap down mounds of tapes. We don't want them sliding 
around, being damaged, or flying up and smacking the rear of our head. 
That volume probably includes the driver, but let's assume we can make up 
for the driver's volume by shifting some tapes to the top of the vehicle 
in a plastic tub and strapping them down. Also, screw having a passenger. 
This is a Fear and Loathing in Las Vegas style cross-country escape from 
the weasels kinda drive. Solo, baby.

Now, let's consider a 9-track tape, at 3600 feet (longest one I could 
find), with a density of 6250 CPI. That should give us 220MB according to 
multiple sources, but hey, spot check me. Now that reel should be a 10.5" 
wide by 5/8" thick. If my math is right, that's 6.56 cubic inches. If I 
take the space in the wagon and try to get my units aligned, that means 
1570.8 in^3. Thus, after division = 239 tapes (even!). So, @220MB that's 

Now for the cigarette box. I'm going to assume you mean the dimensions of 
a *pack* of cigarettes, and since we are all really cool enlightened 
smoker-people, we don't smoke 100s. So, we'll go with the standard size. 
That's @ 6.51 cubic inches, methinks (2 1/8th wide x 3.5" tall x 7/8ths 
thick). A standard SD card is 32mm x 24mm x 1mm. Because of the dimensions 
of the cigarette box doesn't quite factor out to hold the SD cards 
perfectly square, you're not going to be able to pack it completely full. 
If my math is right, you could fit two columns in there with about a 1/4th 
inch of slack. You can, unfortunately, only get two rows stacked in there 
because you end up with about 16.6mm worth of slack at the top (about 
5/8ths of an inch). Now, with the cigarette pack being 7/8ths thick (about 
22mm), we can fit 22 SD cards in one stack and we can shoehorn four stacks 
in our pack. Yeah, the extra plastic is probably bigger than 1mm and it's 
going to bulge a bit, but that's cool. That means we can get 88 SD cards 
in there. Now, we smoke Marlboros, like freakin' John Wayne. Thus, we 
can't really afford the fancy schmancy 128G cards, plus we aren't sure if 
our destination drive can read that huge size card, so let's stick with 
cheap-az 32G cards. That's 2816 GB. 

So what did I screw up?  :-)


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