A ZX Spectrum with a Microdrive emulator plugged into its expansion port

A Modern Replacement For The ZX Spectrum’s Odd Tape Storage System

July 29, 2023 by Robin Kearey 44 Comments

Unless you were lucky enough to be able to afford a floppy disk drive, you probably used cassette tapes to store programs and data if you used pretty much any home computer in the 1980s. ZX Spectrum users, however, had another option in the form of the Microdrive. This was a rather unusual continuous-loop mini-tape cartridge that could store around 100 kB and load it at lightning speed, all at a much lower price point than a floppy drive. The low price came at the cost of poor durability however, and after four decades it’s becoming harder and harder to find cartridges that work reliably. [Derek Fountain] therefore set out to make a modern Microdrive emulator that stores data on SD cards.

Several projects already exist to replace Microdrives, but they typically also need the ZX Interface 1, a serial/network expansion module that’s becoming equally hard to find. Hence [Derek]’s choice to make his emulator a completely standalone system that directly plugs into the Spectrum’s expansion port.

The system is housed in a 3D-printed enclosure that holds two PCBs. Three Raspberry Pi Picos run the show inside: one to hold the ZX Interface 1’s ROM image and interface with the Spectrum’s bus, another to simulate the Microdrive, and a third to run the user interface and communicate with the SD card. The user can choose between eight tape images stored in .MDR format by using two pushbuttons and a rotary encoder, with a small OLED display showing the machine’s configuration.

While you might think that three dual-core 133 MHz ARM CPUs would run circles around the Spectrum’s Z80, it actually took quite a bit of work to get everyting running properly in real time. The 3.5 MHz bus clock rate gave the second Pico precious little time to fetch the required bytes out of its flash memory. Its RAM was fast enough for that, but too small to hold all eight tape images at the same time. In the end, [Derek] settled on using a separate 8 MB SPI DRAM chip that could easily keep up the data rate, with the Pi just using its GPIO ports to shuttle the data around.

All source code and extensive documentation are available on Derek’s excellent blog post and GitHub page. Be sure to also check out [Jenny]’s detailed review and teardown if you’d like to know more about the weird and wonderful Microdrive system.

Thanks for the tip, [Andrew]! Continue reading “A Modern Replacement For The ZX Spectrum’s Odd Tape Storage System” →

AGES Of Renewable Energy Storage

March 3, 2023 by Navarre Bartz 26 Comments

As society transitions toward renewable energy sources, energy storage inevitably comes to mind. Researchers at the University of Illinois at Urbana-Champaign have found one way to store renewable energy that re-purposes existing fossil fuel infrastructure.

While geothermal electricity generation shows a lot of promise, it’s currently limited to a select few areas where hot rock is close to the Earth’s surface. Advanced Geothermal Energy Storage (AGES) stores energy underground as heat and recovers it later, even in places without high subsurface temperatures. For this study, the researchers located an old oil well and instrumented it with “flow meters, fiber optic
distributed temperature sensing (DTS) cable, surface pressure and temperature gauges, and downhole pressure and temperature gauges to monitor the thermal and hydraulic changes during the injection test.”

This field study found that AGES system efficiency could be as high as 82% and yield an “economically viable” levelized cost of electricity (LCOE) of $0.138/kWh. Using existing deep hole infrastructure speeds up site selection and deployment of AGES when compared to developing on an undisturbed location, making this a very interesting way to deploy grid-scale storage rapidly.

We’ve covered reusing fossil fuel infrastructure before as well as challenges and unusual solutions to the energy transition if you’re looking for more about what might be on a future smart grid.

A dark grey couch with a white pegboard on a drawer slide protruding from its arm. The pegboard has a magazine holder, pen holder, and several other miscellaneous bins holding odds and ends on it.

Sofa Armrest Is A Nifty Storage Spot

February 26, 2023 by Navarre Bartz 7 Comments

If you’re like us, you’re always in need of a little more space to store things. [Javier Guerrero] realized his sofa wasn’t living up to its full storage potential and designed this sofa armrest storage.

[Guerrero]’s sofa arms were hiding 80 liters of space, so he really wanted to do something with it. After disassembling them, he found his original plan of just cutting them up wouldn’t work due to the minimal structure inside. Not to be discouraged, he drew up some plans and built replicas from 15 mm plywood.

For one armrest, he made a single giant box that opens from the top where he can store a couple of folding chairs. On the other side, he made a shorter top-opening bin for charging phones and storing the remote. Underneath that is a large pull out drawer with a pegboard for organizational bliss.

The arms were upholstered using the fabric from the original arms plus a little extra from another slip cover. Separate arm modules and easily obtainable matching fabric aren’t a given for every couch, but we expect that almost any sofa with arms could benefit from this hack given a little ingenuity.

If you’re looking for more storage hacks, checkout this Modular Storage from Old Filament Spools, the Last Component Storage System You’d Ever Need, or the ever popular Gridfinity.

Weird Energy Storage Solutions Could Help The Grid Go Renewable

November 29, 2022 by Lewin Day 122 Comments

We’re all familiar with batteries. Whether we’re talking about disposable AAs in the TV remote, or giant facilities full of rechargeable cells to store power for the grid, they’re a part of our daily lives and well understood.

However, new technologies for storing energy are on the horizon for grid storage purposes, and they’re very different from the regular batteries we’re used to. These technologies are key to making the most out of renewable energy sources like solar and wind power that aren’t available all the time. Let’s take a look at some of these ideas, and how they radically change what we think of as a “battery.”

Continue reading “Weird Energy Storage Solutions Could Help The Grid Go Renewable” →

Publish Or Perish: Data Storage And Civilization

October 13, 2022 by Al Williams 120 Comments

Who do you think of when you think of ancient civilizations? Romans? Greeks? Chinese? India? Egyptians? What about the Scythians, the Muisca, Gana, or the Kerma? You might not recognize that second group as readily because they all didn’t have writing systems. The same goes, to a lesser extent, for the Etruscans, the Minoans, or the inhabitants of Easter Island where they wrote, but no one remembers how to read their writing. Even the Egyptians were mysterious until the discovery of the Rosetta stone. We imagine that an author writing in Etruscan didn’t think that no one would be able to read the writing in the future–they probably thought they were recording their thoughts for all eternity. Hubris? Maybe, but what about our documents that are increasingly stored as bits somewhere?

Continue reading “Publish Or Perish: Data Storage And Civilization” →

Aluminium-Sulphur Batteries For Local Grid Storage?

September 5, 2022 by Dave Rowntree 45 Comments

Lithium-Sulphur batteries have been on the cusp of commercial availability for a little while now, but nothing much has hit the shelves as of yet. There are still issues with lifetime due to cell degradation, and news about developments seems to be drying up a little. Not to worry, because MIT have come along with a new battery technology using some of the most available and cheap materials found on this planet of ours. The Aluminium-Sulphur battery developed has very promising characteristics for use with static and automotive applications, specifically its scalability and its incredible charge/discharge performance.

The cell is based upon electrodes constructed from aluminium metal and sulphur, with a electrolyte of molten catenated chloro-aluminate salts. With an operating temperature of around 100 degrees Celsius, you’re not going to want this in a mobile phone anytime soon, but that’s not the goal. The goal is the smoothing out of renewable energy sources, and localised electricity grid balancing. A major use case would be the mass charging of battery electric vehicles. As the number of charge points increases at any given location, so does the peak current needed from the grid. Aluminium-Sulphur batteries are touted to offer the solution to ease this, with their high peak discharge current capability enabling a much higher peak power delivery at the point of use.
Continue reading “Aluminium-Sulphur Batteries For Local Grid Storage?” →