Sorted by Squirrels.

Wednesday, 11 February 2009

MMmm.. Beeb!

I linked to the excellent MMBeeb project in an earlier post. It's been at the top of my project list again as I'm taking a pile of BBC B computers to TechAdventure which I'll be attending at the end of the month. I'm hoping to talk about MMC, old computers and the conjoining of the two. I'll have a table full of retro equipment to show, and some to sell.

As one of the first MMC projects I undertook, the MMBeeb board was a stepping stone that led much further than I expected. Whilst revisiting it in the light of all the knowledge I've acquired since then I've come to the conclusion that there are some subtle bugs with the original hardware. I'm hoping to contact the originator of the project and see what he thinks. I'll post an update here as soon as I've determined if I'm on the right path. In the mean time enjoy the view:





The revised circuit uses the same standard resistor divider as used on every other MMC interface I've ever made and a 3v3 regulator. That's it. It's not the hardware that makes MMBeeb special though - it's the software. It's a stupendously slick DFS conversion that integrates smoothly into a system. It also works with a second processor, which is an indication of the care and attention to detail that Martin has put into his work. And for the few paltry Great British Pounds that it costs for one of these you'd be crazy not to..!

Libraries

It's all go at the moment. Last weekend I attended my first DorkBot London meeting. I must confess I didn't really know what to expect but spent a very pleasant, if cold, day in the company of feverishly soldering artists and makers. I spoke to many people about uFat and the new DevicePrint library. This is some code that allows formatted textual output to a buffer in memory and thus onto some form of persistent storage...


You can get the new library here SMB_LIBRARIES. It adheres to the principles introduced in uFat:- it is lightweight and device agnostic. It should work with any storage medium as long as there is a function available to write a 512 byte sector.

The the code is initialised with a pointer to a buffer, some basic information about the destination sector area, and a writer function. From that point on you are free to use the familiar .print() functions which are best known in their Serial library incarnation. The Arduino base library provides you with so much more than a blinking LED ;)

As usual (1) - there is copious documentation in the form of comments and an example sketch configured to use MMC storage for you to play with. If you wanted to try it out without any devices available then you could always change the write proxy routine to dump the stored data to serial.

As usual (2) - comments welcome!

Toasted and

This is how we do it

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About Sir Morris

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Loves: Old computers, Old Techno, Old ladies. Cake.
Hates: New computers.

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