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

Paul Berger phb.hfx at
Fri Jun 3 15:29:30 CDT 2016

On 2016-06-03 5:21 PM, Swift Griggs wrote:
> 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
> 51.34GB.
> 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?  :-)
> -Swift
Lets not forget that there was no improvement in density of 1/2 inch 
reel since the early 1970s, if they applied modern recording techniques 
the capacity of 1/2"  reel would be greatly improved, the raw capacity 
of LTO cartridges is up to about 8TB per cartridge (they quote 16TB 
compressed but usually that is based on an unrealistic 2:1 compression).

2400 ft reels where more standard the extended length tapes used thinner 
media that was problematic in some drives.


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