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

Fred Cisin cisin at
Fri Jun 3 16:15:43 CDT 2016

>> How many station wagons full of 9-track tapes would fit into a (20)
>> cigarette box filled with microSD cards?

On Fri, 3 Jun 2016, Swift Griggs wrote:
> 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.

That should be 130.9 ft^3  CUBIC feet, not square feet.

> 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

How are you calculating that??
If it were "square", then it would be length * width * height
quite a bit more than you came up with.
If round, then PI * R * R

However, round objects waste some space.  So, assume the square or 
hexagon that circumscribes that circle (that they would fit in).

I would not leave the back seats in.  If we pack the tapes in tightly, 
then there is no need for any seat except driver.  (Shall we assume that 
we do not have convenient access to an autonomous car?)
I'd try to avoid that tub on the roof - gas mileage is already pretty 

> take the space in the wagon (130.9 ft^3) and try to get my units 
aligned, that means 1570.8 in^3.
130.9 cubic feet (if correct) is most certainly not 1570.8 cubic inches.
There are not 12 cubic inches in a cubic foot, there are 12 * 12 * 12
Therefore, 130.9 cubic feet would be 226195.2 cubic inches.

> 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.
I was unaware of that.

> 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.
BUT, the original was MICRO-SD.  Those will pack into the cigarette pack 
with far less wasted space.

> 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.

agreed.   Those are currently at a good price point.
BUT, we will go with MICRO-SD[HC], which has more than 4 times the data 
capacity to physical volume, at least whe considering the more efficient 
BUT, if we hold tightly to the original wording, Micro-SD (V Micro-SDHC) 
tops out at 2G each.

> That's 2816 GB.

> So what did I screw up?  :-)
cubic feet to cubic inch conversion
calculation of volume of a tape
use of SD[HC] instead of MICRO-SD[HC]

Seagate makes a 2.5" 2TB (1.81TiB) SATA hard drive.   They're a little 
hard to find right now, but readily available (and cheaper) if you buy 
their Backup-Plus-Slim, and throw away the external drive housing.  Two 
of those is about a cigarette pack in size.  I sometimes carry two of 
those in my shirt pocket.

But, further considerations:
Is this going to be a one shot transfer, or an ongoing operation?
Where are the endpoints?
If we assume about 50 hours to drive cross the USA, that provides a long 
data transfer time, whereas a cigarette pack of Micro-SDs could be in your 
pocket on a plane (if TSA will let you through)  How many cigarette packs 
can you fit into an accepted carry-on bag? (Nobody wants to pay excess for 

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