When I started at Clarkson in 1978, they had a IBM System/360 65J. Announced in 1965, it was obsolete long before I laid on eyes on it, but it was far faster than anything I had touched, and best of all, it had video terminals with erasing backspaces.
Physically, the machine required five full size frames (hence the term "mainframe") for the CPU and 1 MB main (core) storage. There were also frames for 3 MB of Large Core Storage, which was bigger but slower than the main storage. The IBM System/360 Installation Manual-Physical Planning runs 161 pages.
For disk storage, the S/360 had three IBM 2314 direct access storage facilities with eight online disk drives each. Each drive had 11 14" platters holding a total of 29.2 megabytes. With 24 drives (each the size of a commercial washer) across the 3 banks, the system had 699 megabytes online total. (By the mid-1990s, that storage would fit on a fraction of a single Windows 95 5.25" hard disk.)
Now? CPU, memory, and disk drives are even smaller, to say the least:
|Kingston 240 GB M.2 drive measuring 80 mm by 22 mm
The interesting thing is that these drives are small enough to fit in new places. Formerly, if one wanted to put better drive than an SDXC card on a single board Raspberry Pi, one had to use an external 2.5" drive with a USB cable; that's a tad smaller than a 2314 drive, but still annoying.
But now, people such as Argon 40 are building quality cases for the Raspberry Pi 4b (compare the below to the plastic cases I used for Raspberry Pi 3b units). The Argon 40 cases look great, act as large passive heat sinks, and have thermostatically controlled fans for when passive cooling isn't enough. Better still, they have added similar cases (and adapters for existing cases) that hide the M.2 drive away.
|On the right: An Argon One case exposing the bottom of the installed Raspberry Pi 4b
On the Left: a simple base for the case (no drive)
In the Center: the Kingston M.2 drive from above installed in an expansion case base
|Two Argon One cases, with & without
the higher expansion base for a M.2 drive
|The Argon One expansion base uses a U-shaped USB3 connector
to make the electronic connection between the base and the case.
Note: Click on any of the photographs for a larger image.