A Very 2017 Take On A BBC Micro

In the early 1980s, there were a plethora of 8-bit microcomputers on the market, and the chances are that if you were interested in such things you belonged to one of the different tribes of enthusiasts for a particular manufacturer’s product. If you are British though there is likely to be one machine that will provide a common frame of reference for owners of all machines of that era: The Acorn BBC Microcomputer which was ubiquitous in the nation’s schools. This 6502-driven machine is remembered today as the progenitor and host of the first ARM processors, but at the time was notable for the huge array of built-in interfaces it contained. Its relatively high price though meant that convincing your parents to buy you one instead of a ZX Spectrum was always going to be an uphill struggle.

So, you never owned a BBC Micro, and this has scarred you for life. Never mind, all is not lost, for now you can have that Acorn experience without scouring eBay for a classic micro, by running one entirely in silicon on a myStorm FPGA board.

To be fair, running classic hardware on an FPGA is nothing new and there have been a few BBC Micros implemented in this way, not to mention an Acorn Atom. But this project builds on the previous FPGA BBC Micros by porting it entirely to Verilog and incorporating some of the bug fixes from their various forks. There are screenshots of the result running several classic games, as well as test screens and a benchmark revealing it to be a faithful reproduction of a 2MHz BBC Micro.

We covered the myStorm board when it arrived last year. We’ve also brought you another FPGA board running as a coprocessor for a real BBC micro.

Thanks [monsonite] for the tip. He also alerts us that the myStorm board’s ARM microcontroller can now be programmed from the Arduino IDE.

A Universal USB To Quadrature Encoder

Computer mice existed long before the Mac, and most of the old 8-bit computers had some software that could use a mouse. These mice had balls and quadrature encoders. While converters to turn these old mice into USB devices exist, going the other way isn’t so common. [Simon] has developed the answer to that problem in the form of SmallyMouse2. It turns a USB mouse into something that can be used with the BBC Micro, Acorn Master, Acorn Archimedes, Amiga, Atari ST and more.

The design of the SmallyMouse2 uses an AT90USB microcontroller that supports USB device and host mode, and allows for a few GPIOs. This microcontroller effectively converts a USB mouse into a BBC Micro user port AMX mouse, generic quadrature mouse, and a 10-pin expansion header. The firmware uses the LUFA USB stack, a common choice for these weird USB to retrocomputer projects.

The project is completely Open Source, and all the files to replicate this project from the KiCad project to the firmware are available on [Simon]’s GitHub. If you have one of these classic retrocomputers sitting in your attic, it might be a good time to check if you still have the mouse. If not, this is the perfect project to delve into to the classic GUIs of yesteryear.

SCSI Emulation Of A Rare Peripheral For The Acorn BBC Micro

Mass storage presents a problem for those involved in the preservation of older computer hardware. While today’s storage devices are cheap and huge by the standards of decades ago their modern interfaces are beyond the ability of most older computers. And what period mass storage hardware remains is likely to be both unreliable after several decades of neglect, and rather expensive if it works due to its rarity.

The Domesday Project 86 team face this particular problem to a greater extent than almost any others in the field, because their storage device is a particularly rare Philips Laser Disc drive. Their solution is the BeebSCSI, a small board with a CPLD and an AVR microcontroller providing host adaptor and SCSI-1 emulation respectively for a modern micro-SD card.

An original BBC Domesday set-up. Regregex [CC BY 3.0], via Wikimedia Commons.
An original BBC Domesday set-up. Regregex [CC BY 3.0], via Wikimedia Commons.
1986 saw the 900th anniversary of the Domesday Book, a survey and inventory of his new kingdom commissioned in 1086 by the Norman king of England, William the Conqueror. One of the ways the event was marked in 1986 was the BBC Domesday Project, a collaboration between the BBC, several technology companies including Acorn and Philips, and a huge number of volunteers from the general public and the British school system. Pictures, video, and text were gathered relating to locations all over the country, and the whole was compiled with a not-quite-hypertext interface onto a set of Laser Disc ROMs. The system required the upgraded Master version of the 6502-based BBC Micro, a SCSI interface, and a special Laser Disc player model manufactured by Philips for this project alone. The hardware was expensive, rare, and unreliable, so few of its contributors would have seen it in action and it faded from view to become a cause celebre among digital archivists.

There have been several resurrections of the project over the years, including one from the BBC themselves which you can browse online. What makes this project different from the others is that it strives to present the Domesday experience as it was originally intended to be viewed, on as far as possible the original hardware and with the original BBC Micro interface. Many original parts such as BBC Master systems are relatively easy to source in 2016, but the special Laser Disc player is definitely not. This board replaces that impossible link in the chain, and should allow them to present a glimpse of 1986 in more than just the on-screen information.

If you would like to see an original BBC Domesday Project system, you can find one in action at the National Museum of Computing, at Bletchley Park. Meanwhile we’ve already featured another peripheral from the same stable as this one, the SmallyMouse USB-to-quadrature mouse emulator.

A 150MHz 6502 Co-Processor

If you are familiar with ARM processors, you may know of their early history at the 1980s British home computer manufacturer Acorn. The first physical ARM system was a plug-in co-processor development board for Acorn’s BBC Micro, the machine that could be found in nearly every UK school of the day.

For an 8-bit home computer the BBC Micro had an unusually high specification. It came with parallel, serial and analog ports, built-in networking using Acorn’s proprietary Econet system, and the co-processor interface used by that ARM board, the Tube. There were several commercial co-processors for the Tube, including ones with a 6502,  a Z80 allowing CP/M to be run, and an 80186.

As with most of the 8-bit generation of home computers the BBC Micro continues to maintain a strong enthusiast following who have not stopped extending its capabilities in all directions. The Tube has been interfaced to the Raspberry Pi, for instance, on which an emulation of original co-processor hardware can be run.

bbc-tube-screenshotAnd thus we come to the subject of this article, [Hoglet] and [BigEd]’s 150MHz 6502 coprocessor for the BBC Micro. Which of course isn’t a 6502 at all, but a 6502 emulated in assembler on an ARM which is in a way the very distant descendant of the machine it’s hosted upon. There is something gloriously circular about the whole project, particularly as the Pi, like Acorn, the BBC Micro, and modern-day ARM, has its roots in Cambridge. How useful it is depends on your need to run 8-bit 1980s software in a tearing hurry, but they do report it runs Elite, which if you were there at the time we’re sure you will agree is the most important application to get running on a BBC Micro.

We’ve featured the Tube interface before when we talked about an FPGA co-processor with a PDP/11 mode that was definitely never sold by Acorn. And we’ve also featured an effort to reverse engineer the primordial ARM from that first BBC Micro-based co-processor board.

BBC Micro image: Stuart Brady, Public Domain, via Wikimedia Commons.

BBC’s micro:bit Gets Python

The BBC has developed a computer to be used by thousands of students across the UK. While not very powerful in terms of hardware, it comes with an interpreted language that will get students writing their own code and will launch the careers of an entire generation of web developers. This is, of course, the BBC Micro, a computer introduced in 1981, but is still deeply revered by millions of former students.

Microcontrollers are everywhere now, and the BBC is looking to replicate their success with the micro:bit. Unlike the BBC Micro, this isn’t a proper computer with a keyboard and a monitor. Instead, it’s a microcontroller development platform based on an ARM chip. Now, the micro:bit is getting Python, the BASIC of today, and will assuredly be even more useful in UK classrooms.

The initial development for Python on the micro:bit started down the road of using Microsoft’s TouchDevelop as a browser-based IDE that would send C++ code to an mBed cloud compilation service. A hex file would be generated, this would be downloaded to the local file system, and finally the student would simply drag the hex file over to the micro:bit since it appeared on the desktop as a USB storage device. This was a terrible idea, because MicroPython exists. The current way of running Python on the micro:bit is as simple as plugging it in to a USB port, opening a terminal, and writing some code. It’s the closest you’re ever going to get to a computer with BASIC in ROM, and it’s the best device for millions of 11-year-olds to learn how to code.

Thanks [dassheep] for the tip.

Vintage BBC Computer gets FPGA Buddies

The BBC Microcomputer System (or BBC Micro) was an innovative machine back in the early 1980’s. One feature that impressed reviewers was a “tube” interface that allowed the machine to become an I/O processor for an additional CPU. When the onboard 6502 became too slow, it could become a slave to a Z-80 or even an ARM processor. The bus was actually useful for any high-speed device, but its purpose was to add new processors, a feature Byte magazine called “innovative.”

[Hoglet67] has released a very interesting set of FPGA designs that allows a small board sporting a Xilinx Spartan 3 to add a 6502, a Z80, a 6809, or a PDP/11 to a BBC Micro via the tube interface. There’s something satisfying about a classic computer acting as an I/O slave to a fairly modern FPGA that implements an even older PDP/11.

Continue reading “Vintage BBC Computer gets FPGA Buddies”

Micro:bit — BBC Gets A Million Kids Into Embedded Dev

In the Early 1980s, the BBC launched a project to teach computer literacy to a generation of British schoolchildren. This project resulted in the BBC Micro, a very capable home computer that showed a generation exactly what a computer could do. These children then went home, turned on their ZX Spectrums, and became a generation of software engineers. Still, the BBC Micro is remembered fondly.

The computer revolution is long over, but today we suffer a sea change of embedded processors and microcontrollers. With Arduinos and Raspberry Pis, the BBC has decided it’s time to put the power of an ARM microcontroller into the hands of a million 11- and 12-year olds. The result is the Micro:bit. It’s a small microcontroller board with an ARM processor, an IMU, buttons, Bluetooth and a 5×5 LED array – exactly what you need if you’re teaching a million kids how to blink an LED.

Although the BBC has finalized the design for the Micro:bit, there are no specs at all. However, a few educated guesses can be made. The USB controller is provided by Freescale, who also provide the digital compass and magnetometer. Programming is done through a web-based, Arduino-like IDE with what appears to be a decent Micro:bit specific library. The board is also mbed compatible. Bluetooth, and apparently the ARM Cortex M0 core, is provided by a Nordic nRF51822. There are only three alligator clip-compatible I/Os, and its doubtful any student will be building anything that would be too complex for an entry level ARM. It’s also 3V logic; finally, the tyranny of 5V has fallen.

The Micro:bit is best seen as a tool that enables the relatively recent addition of a computer science curriculum in UK schools. There is now a requirement for seven-year-olds to understand algorithms and create simple programs. Previously computer education in the UK has consisted of PowerPoint. Now, secondary school students will be learning Boolean logic.

While the Micro:bit is utterly useless as a tool for doing real work, education is not real work. For blinking a few LEDs, having a device react to movement, playing with Bluetooth, and other lesser evils of electronics, the Micro:bit is great. Not everyone will become the digital technologists this initiative is trying to create, but for those who have an inclination towards semicolons and electrons, this is a great introduction to technology.