Jan 2025 – 5th Wed – Data Storage

At the Society, the fifth Wednesday of the month (for months that have one) is Show and Tell night; the theme for January was Data Storage:

The invite said: “Who remembers punched cards and magnetic core memory? Tape in all formats, USB sticks, chips, floppy disks, laser etc. ROM … à la read only memory … how does it get there in the first place??? Best display by vote, best story selected by the judge in charge!”

What a night it was!

Emmanuel VK2EMM’s display

• Limited edition “Black Album” by Metallica on vinyl
• Limited edition Somewhere in Time on vinyl
• TI-84 plus CE with games such as Pac-Man, chess, Snake, Tetris, and more!

Emmanuel’s story: “For my new school this year I needed a new fancy TI graphing calculator, which I got a couple days ago. After a bit of tinkering I discovered it could run python, which led me searching around and finding that you could actually flash games onto it! Perfect for playing in boring classes! For those interested: https://www.ti84calcwiz.com/“

Clifford VK2CLF’s display

Clifford’s display was, in order:

• an 85MB IDE hard disk drive
• a 3.5” floppy drive
• a 5.25” floppy drive
• an 8” floppy with a story (below)!

Clifford’s story: “The May 1980 issue of Dr Dobb’s Journal of Computer Calisthenics and Orthodontia – Running light without Overbyte contains the first instalment of A Small C Compiler for the 8080’s by Ron Cain. With friends, we typed in the code and got it running on the VAX-11/780 running VMUnix at Melbourne University, and verified that it could compile itself, yielding a large volume of 8080 assembly code. No 8080 computer or assembler was available, but my summer employer had a Cromemco S-100 bus computer running two 8” floppy drives. The only 8” floppy drive available at the University was the one attached to the PDP-11 which held the boot loader for the VAX, and as an undergraduate I had to get permission to enter the computer room to access it.

“The floppy contains the assembly code I took to Mark Pammer & Associates to assemble on their Cromemco.

“The associated program listing is the Pratt parser (a precedence-driven parser) that I wrote with the goal to replace the recursive descent expression parser of Small C.

“The PDP-11 did not have tools to read or write CP/M filesystems. I had to write my own. My first time using the PDP-11 floppy drive was to extract an image of a CP/M formatted disk. I took that image away and used it to test my new program, car, which could read and write CP/M format floppies. Then used car to write the assembly code of Small C onto a new blank disk image, and got access to the drive a second time to save that image onto the floppy I show here.”

Yves VK2AUJ’s comment: In early 1980s we ran a pilot project providing desktops for a government office for people to have a go at word processing, we had to put a sign next to the printer “Do not staple the disk to your printed document”.

Des VK2TGJ’s Display

Richard VK2ARH’s Winning Story

Richard’s story covered the early days of the defence communications network where RTTY signal traffic was routed via an old AWA computer which utilised drum memory, and any changes to the transmit and receive traffic channels required programming with a soldering iron. He also spoke of how, despite the modernisation of computer systems in the early 80’s, one of his first tasks was to fault find an erroneous computer program used for the Army’s Promotions Review Board, only to discover that the program was stored as a 4’ high stack of IBM punch cards. How times have changed. 

Michael VK2MDP’s display

Michael’s display was a filing system for CDs and DVDs. Michael also reflected on the challenge of archiving digital documents and photographs as technology changes. So much valuable historical records came to us printed on paper in books and manuscripts that last for 100’s of years if stored carefully. How are we going to make sure digital records continue to be available in future?

No one is going to go through a granny’s computer after her death to see if there is any valuable historical information to retain, like we used to do when finding old photo albums or diaries in the attic.

Yves VK2AUJ’s display

Player Piano roll, 88 keys recording. Interestingly picked up from the side of the road at Rhodes during the quarterly council clean-up, there were piles of them!

Tim VK2TIJ’s display

The “voicewriter dictation machine”, commonly known as a Dictaphone, was produced throughout the 1950s by Thomas A. Edison, Inc. Tim mentioned that it could be considered a digital storage if you were to dictate something like: “zero, one, one, one, zero, zero, one …” 😉 Check this short YouTube video demonstrating how the soft disks were used.

Dave Jones EVVBlog’s display

The first computer memories were Magnetic Core Memories. Below is a sample provided to us by Dave from EEVBlog. See the full story on his YouTube channel.

Then came the disks!

• IBM Hard Drive
• Model : IBM Model 3390 mod2
• Year of manufacture: 1989
• Capacity: 1.89GB or 3.78GB
• Original cost: $250,000
• Owner: Dave Jones (EEVBlog.)

The unit shown isn’t the complete drive; it’s just the head-disk assembly (HDA). The full drive, with power supplies and electronics cards was about the size of a washing machine, and that still wasn’t enough to get the data on and off the discs, as the drives had to be connected to a controller unit that handled a string of 8-16 drives. This drive is more advanced, having an integral spindle motor, but the 14-inch drives that preceded it in the 1980s were belt-driven by 3-phase induction motors about the size of what you would find in a washing machine.

See Dave’s IBM HDD teardown video.

Mal VK2TMF’s display

Mal VK2TMF also set-up a display of a Commodore 64 where the game was loaded “live” in front of us from a cassette player with the comment: “I’m the only one this evening that can demonstrate extracting data from an old media”.

Manual: https://project64.c64.org/Hardware/Peripherals/cassette.pdf

Wikipedia page: https://en.wikipedia.org/wiki/Commodore_Datasette

The winners