The Laptop Every British Kid Would Have Wanted For Christmas 1983

December 17, 2023 by Jenny List 12 Comments

How can we convey to a world in which a 64-bit laptop can be a near-throwaway item, just how amazing a miniature laptop version of the 1980s Sinclair ZX Spectrum could have been? perhaps we don’t need to, because here in 2023 there’s a real one for all middle-aged geeks who had the original to drool over.

8-bit home computers were super-exciting for the kids of the day, but they were in no way portable and relied on a TV, frequently the family model in the living room. It’s safe to say that a portable version of one of those home computers, not in an Osborne-style luggable case but in a clamshell palmtop, would have been mind-blowing, so four decades later we’re fascinated by [Airrr17]’s portable Sinclair ZX Spectrum.

At its heart is a dev board using one of the STM32F4 series microcontrollers, and running the Spectrum as an emulator. Alongside that is an LCD, and perhaps what is physically the best part of this, a Spectrum keyboard complete with BASIC keyword decals, made with large-button tactile switches that have we think, printed paper on top. Add in a small lithium-polymer cell and associated electronics in a cute little palmtop case, and it’s about as good a portable Sinclair as we could have imagined. All the details can be found in a GitHub repository, and as if that weren’t enough there’s an assembly video we’ve placed below the break.

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ZX Spectrum Gets A 3D FPS Engine

September 12, 2023 by Lewin Day 21 Comments

The Sony PlayStation and Nintendo 64 are well-known for bringing 3D gaming into the mainstream in a way that preceding consoles just couldn’t. The ZX Spectrum, on the other hand, is known for text adventures and barebones graphics. However, it now has a rudimentary version of a Quake-like engine, as demonstrated by [Modern ZX-Retro Gaming].

As you might expect, the basic ZX Spectrum that sat in front of your dodgy old TV in the 1980s isn’t really up to the task of running a full 3D game. The engine runs at a fairly jerky frame rate on a 3.5 MHz ZX Spectrum, with purely monochrome graphics. However, the game can run more smoothly on 7, 14, and 28MHz ZX Spectrum compatibles. As with many such projects, most of the video you’ll see is of the game running in emulators. Impressively, the game features sound effects, three weapons, and a standard WASD control layout as per modern FPS games.

If you’re wondering about the confusing visuals, there’s a simple explanation. Yes, the UI and weapons are straight out of Doom. However, the game is running on a true 3D engine, with 3D enemies, not sprites. It’s inspired by the full 3D engine pioneered by Quake, hence the designation.

Files are available for those wishing to try it out at home. We do see a fair bit of the ZX Spectrum around these parts. Video after the break.

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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” →

A Pico-Based ZX Spectrum Emulator

June 21, 2023 by Lewin Day 18 Comments

The ZX Spectrum was a popular computer of the 8-bit era. Now, it’s possible to emulate this machine on a microcontroller so cheap that it’s literally been given away on the front cover of magazines. Yes, we’re talking about the Pico ZX Spectrum project.

The project consists of all the necessary code to emulate a ZX Spectrum upon the hardware of the RP2040 microcontroller that makes up the Raspberry Pi Pico. The community has then taken this code and run with it, using it as the basis for all manner of different ZX Spectrum builds. If so desired, you can go barebones and use the Pico to run a ZX Spectrum off a breadboard with HDMI video output. Alternatively, you can build something like the PicoZX from [Bobricius]. The handheld computer features a PCB-based housing, along with an LCD and an integrated keyboard. Other configurations support features like USB keyboards, VGA outputs, and working sound output.

It’s great to see a classic 8-bit computer reimagined in all kinds of new tribute form factors. The Spectrum was always beloved for its neat all-in-one design, and there are several modern remixes that riff on that theme. The fact that they can all be powered by a cheap single-board microcontroller is all the more astounding. Video after the break.

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Recreating The ZX Spectrum Unboxing Experience By Manufacturing A New Boxed One

March 26, 2023 by Maya Posch 7 Comments

Why scour the internet for a rare-as-hen’s-teeth new in box ZX Spectrum computer when you can instead order up some parts, assemble a basically all new ZX Spectrum along with the box, instruction manuals and more?

That seems to have been the reasoning behind [Lost Retro Tapes] when they decided to do exactly that. Along with the announcement of the completion on Reddit, the website details the BOM and sourcing the components.

For the mainboard, an existing, redrawn ZX Spectrum 48 Issue 3B PCB was found and ordered from PCBWay. As a UK-based entity, many of the other components were sourced from retro computing shops around the UK, but with all but the LM1889N IC being available for new or with currently produced alternative, it should be viable to source them locally.

Perhaps most impressive was the creation of the box (unfortunately not detailed on the website at this point), and having the manuals (system and BASIC) professionally printed and bound. Along with a few other bits and pieces, including a tape recorder and fresh Horizons tape, the total price tag came to around £412.

Thanks to [Lee Hodgson] for the tip.

Addressable LEDs From A Z80

January 19, 2023 by Jenny List 3 Comments

If you buy WS2812s under the Adafruit NeoPixel brand, you’ll receive the advice that “An 8 MHz processor” is required to drive them. “Challenge Accepted!“, says [ShielaDixon], and proceeded to first drive a set from the 7.3 MHz Z80 in an RC2014 retrocomputer, and then repeat the feat from a 3.5 MHz Sinclair ZX Spectrum.

The demos in the videos below the break are all programmed in BASIC, but she quickly reveals that they call a Z80 assembler library which does all the heavy lifting. There’s no microcontroller behind the scenes, save for some glue logic for address decoding, the Z80 is doing all the work. They’re all implemented on a pair of RC2014 extension cards, a bus that has become something of a standard for this type of retrocomputer project.

So the ubiquitous LEDs can be addressed from some surprisingly low-powered silicon, showing that while it might be long in the tooth the Z80 can still do things alongside the new kids. For those of us who had the Sinclair machines back in the day it’s particularly pleasing to see boundaries still being pushed at, as for example in when a Z80 was (almost) persuaded to have a protected mode.

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A 3D-printed case for the ZX Spectrum with a mechanical keyboard

The ZX Spectrum Finally Gets A Proper Keyboard

December 27, 2022 by Robin Kearey 38 Comments

The Sinclair ZX Spectrum is fondly remembered by many for being their first introduction into the wonderful world of computing. Its advanced capabilities coupled with a spectacularly low price made it one of the great home computers of the 1980s, at least in the UK and nearby countries. What was less spectacular about the Spectrum was its awful keyboard: although a step up from the flat membrane keyboards of earlier Sinclair computers, the Spectrum’s tiny rubbery keys made typing anything more than a few characters a bit of a chore.

If you’re planning to do any serious programming on your Spectrum, you might therefore want to check out [Lee Smith]’s latest project in which he redesigns the Spectrum’s case to include a proper mechanical keyboard. [Lee] got this idea when he was looking for ways to fix a few Spectrums with broken or missing cases, and stumbled upon several projects that aim to recreate classic Sinclair machines using modern components. He took a keyboard PCB meant for the ZX Max 128 project, populated it with some high-quality switches, and added a modified set of keycaps from the ManuFerHi N-Go.

A new ZX Spectrum case, opened to show the keyboard connecting to the mainboard — The new keyboard plugs into the original connectors and doesn’t require any board-level modifications.

Together, those parts formed a modern, comfortable keyboard that still had the proper labelling on all keys. This is rather essential on the Spectrum, since each key is also used to generate symbols and BASIC keywords: for instance, the “K” key also functions as LIST, +, LEN and SCREEN$.

With the keyboard design settled, [Lee] set to work on the rest of the case: he designed and 3D-printed a sleek enclosure that takes the new keyboard as well as an original Spectrum mainboard. The resulting system is called the ZX Mechtrum, and looks fabulous with its matte black exterior and the obligatory four-coloured rainbow. A replaceable rear panel also allows several board-level modifications, like composite video or VGA output, to be neatly incorporated into the design.

We wrote an extensive retrospect on the Spectrum on its 40th anniversary earlier this year. If, somehow, you actually like the Spectrum’s original rubbery keyboard, then you can also modify the whole thing to work with modern computers.

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