Wednesday, February 10, 2016

Fignition Revisited

The original WiNode 4.0 plus Evita video board 

Recently I have been thinking again about simple 8-bit computer systems.  By simple, I mean understandable, to me, and those that don't rely on 20 million lines of someone else's code to get to the point that you can have fun with them.

The early 1980s was a very prolific period of design for home computers, especially in the UK, before the very costly IBM PC really took a hold. Costly in the fact that it cost about £3000 in 1981 and very costly to the UK computer industry.

Many of these, now 35 year old computers are being revisited and recreated, possibly using new hardware, to create a whole genre of neo-retro machines.

Some History.....

Way back in 2011, I developed an "augmented Arduino"  which I called WiNode - a concatenation of Wireless Node.

It featured the ubiquitous ATmega328, an RFM12B 433 wireless transceiver, a real time clock, a microSD connector, a 32kbyte battery backed SPI SRAM and a dual H-bridge for driving small motors and relays.

One of the production batches of WiNode was used in a sound-sculpture installation "Phantom Railings"  at Malet Street Gardens in summer of2012.

About the same time, whilst at Oggcamp 2012, I met Julian Skidmore, who had created a small DIY kit for an 8-bit Forth Computer, called Fignition.

Julian had done a great job in getting it to run a very capable implementation of Forth, and produce audio and video from just an ATmega328.

The Plan.....

Whilst recently reconsidering the role of 8-bit computers, and languages such as Forth, I remembered Julian's work, and WiNode, and wondered whether they might both benefit from an upgrade.

I have subsequently upgraded WiNode to use the much more resource rich ATmega1284, with 16K of onchip RAM and 128K of flash.  By my reckoning that probably puts it on par with an original 16K Spectrum. However, according to Julian's Forth benchmark figures, when clocked at 16MHz, an ATmega is going to outperform a 3.5MHz Z80A by a factor of about 24.

In the intervening years, Fignition has gained a PS/2 keyboard interface, and is now showing all the signs of a very useful machine for learning to program in Forth. It easily exceeds all the capabilities of the early 1980's Jupiter ACE.

The new WiNode design is a good way of taking the Fignition concept a stage further.   It provides much needed additional RAM capacity,   the super-capacitor backed 32kbyte SPI SRAM can now be used as a persistent store - rather than the main execution RAM  - a much needed speed increase, and the microSD card may be used for removable program storage, put all your favourite Fignition games on uSD and share with your friends.....

WiNode also brings on-board wireless connectivity, either using the RFM69  433MHz or 868MHz low power transceiver, or the plug-in ESP8266 WiFi module.

WiNode by itself is really intended as a stand alone controller, with 28 general purpose I/O lines. The realtime clock, LiPo battery support and non-volatile RAM/uSD card means that it is a good fit for data logging, central heating control, internet connectivity (WiFi) , energy monitoring etc.

However, WiNode 5 has been designed to work with a video generation shield, called Evita, which allows full colour video of up to 1024x768 65Hz resolution via a VGA connection to a large screen monitor.  The Evita board also provides PS/2 keyboard and mouse interfaces, audio output, connection to a LCD touchscreen and also to a joystick or Wii Nunchuck controller. All the right interfaces for a colourful neo-retro computer system.

No comments: