A tale of two Beebs: the road to Elite

Post date: 22-Jan-2010 14:20:37

We recently realised that our 816 board is about ready to be tried on some serious software. The best example is of course Elite, the ground-breaking 3D space combat and trading game.

To run a game, we need to load it, and so it was time to see if our upgrade is compatible with the disk storage of the day. So far, we'd done our experiments with a serial connection to a host, and pasted in test code in BASIC or srecord format - or added it to our ROM.

Many original Beebs were bought without a floppy disk controller, and needed an OS upgrade to support one. Ed's was one such. By the time he came to upgrade (£120?) there was a choice of two disk controller chips and several different ROMs. The original chip - an Intel 8721 - was the more expensive option, and so Ed's Beeb, until recently, had a WDC 1770 chip and a Solidisk ROM.

It also has defective RAM.

Our loaner Beeb had a less constrained history, and had the 8271 controller, and doesn't scribble all over its own memory.

At the first attempt, we were able to read the disk catalogue. But trying to load Elite failed with a disk error. We could only read the first block or so of any file. We have to conclude, for now, that the 8271 won't work with our 816.

Swapping to Ed's machine, after some tactical wobbling of the power connector, success! Elite will load, sometimes, and play for a few seconds before decaying memory gets the better of it.

So the 816 can happily run the code which drives the 1770 controller.

All that remained was a tense session of removing 8 chips, replacing 2, replacing the 8271 with the 1770 daughterboard and fitting the two jumpers needed for the Solidisk kit. Then swapping the DFS ROM. Then reconnecting the keyboard. No boot. Reconnecting the keyboard correctly...

Success! On 17th Jan 2010, Elite ran on our Level 1b board.

Next step: turning up the clock.