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Digital Storage – How much did they hold? Nostalgia!

February 15, 2018

For those around in the 1980’s for the ZX-81 computer and ZX Spectrum, Commodore 64, you will remember the old audio cassette tapes used to load your games/programs. The evolution from even further back to now has been quite astonishing.

Not only have prices per Gb fallen dramatically, physical size of storage for digital data has dropped dramatically.

Recently, a Facebook friend of mine showed me this and I thought this may be an interesting article to tour down Nostalgia lane of my IT experience. These are 5 Megabyte (5 Million Bytes) Hard Disks being loaded in 1956 onto a truck and plane.

This was my second “computer” / gaming console – the Atari. The first was a Pong type controller / console.

At one point, my father purchased me an overlay that permitted me to program in an old form of BASIC (this was like 1980’s or so) – I tried googling, but I remembered it looking similar to this.

It was too long ago. I can’t remember how much memory it had. It may have been as low as 512bytes or 1024 bytes (ie 1 Kb), but it was my first introduction to programming.

I distinctly remember it was a bubble-type (aka Membrane) add-on keyboard. It may or may not be the exact image depicted, but the colour and format look familiar to my recollection of 35+ years or so ago. It fitted over the top of the Atari game console, however. I don’t recall having the ability to save code. It had some cables that plugged into the joystick ports as well.

Later, we got a ZX81 computer to play with – I think it had 16k or so of memory (the pack at the back was the additional memory) and you could program in BASIC /or assembly language.

Then, my brother got a ZX48k for Christmas – and I basically “claimed it” – it had 48K memory and later they released a 128k model which I never owned as I got a PC.


The ZX range allowed you to use an audio cassette player to store information and load games / programs. [3]

It was a very time-consuming process and data / games was stored from an Audio Cassette tape via a cassette player as below:

These tapes had 30 to 45 minutes of storage on each side (later even C120’s with 60min per side) could (on average) store about 68400 bytes. (about 66Kb) [1]

Some forms of data storage could push a bit more, but these magnetic tapes were prone to stretching and audio quality degradation over time.

Then, in about 1983 or so I got access to an IBM PC (at school) which had “massive” 8″ 180Kb floppy disks, then later in 1987, my own IBM XT compatible clone PC (this had a clock speed of a whopping Turbo 8MHz).

The computer had no hard disks, only 51/4” 360Kb floppy disks. As new PC’s came out these became 51/4” 1.2Mb floppy disks, then 31/2” 1.44Mb stiffy disks.

Some time later, I got a second-hand 10Mb 51/4 Full height Micropolis  internal hard disk or so, then I got my first Seagate ST225 20Mb Hard Disk.

The  51/4” form factor (the size of an old floppy drive stayed around for quite some time, then the  31/2 became more popular, then the  21/2” became the standard for notebooks and super fast SSD’s.

Then came CDROM drives – holding a whopping 650Mb of data. Then DVD’s which looked similar, but had 4.7Gb of storage.

Today, pretty much the lowest size hard disk in PC’s is 1000 GigaByte /or 1 Terabyte, but 500gb is quite popular as well.

Form factor has just become related to speed, with camera’s using SD cards that are the size of a fingernail holding 64 to 500gb of high speed storage, but with PCIE SSD cards, even this line is becoming blurred with exceptionally high speed drives now being the size of a memory chip that just plugs straight into your computer /notebook.

Digital Data Representation / Calculations:
1 BIT (either a 1 or a 0)
8 BITs = 1 Byte, eg. a letter like A, B, or C, etc is a byte of Information.
1024 bytes = 1 Kilobyte
1024 Kilobytes x 1024 = 1048576 Kilobytes = 1 Megabyte
1 Megabyte x 1024 = 1048576 Megabytes = 1 Gigabyte
1 Gigabyte x 1024 = 1048576 Gigabytes = 1 Terabyte

– please note that most manufacturers divide the Kilobytes by a factor of 1000 (instead of 1024), so a 500Gb drive will be displayed as 465Gb in Windows.
Manufacturers just round it off. Computers divide by 1024, not 1000 So, they will go – 1024 x 1024 x 1024 x 465 / 1000 = +/- 500 “Gb”

~ Craven Coetzee / ICT Consultant

this article is a Work In Progress – more to be added.


  1. Audio Cassette Tape Storage – How much could you store? http://www.myprius.co.za/tape_storage.htm
    “Average medium transfer rate is approximately 307 bps (38 bytes/sec) for files that contain 50% of “0” and “1” bits each.”
  2. Tape Decoding – Audio Cassette Storage – http://www.worldofspectrum.org/tapsamp.html
  3. A demo of a program loading via Cassette Tape (Spectrum 128k) – YOUTUBE VIDEO





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