DRAGON Beta - Prototype

Aka. Dragon 128 (256)

Project Beta was something altogether different, and saw GEC Dragon really wanting to hit the big time. Expecting to retail at £2500-3000, the micro housed twin 68B09 processors, had 256K RAM (expandable to 768K) and offered two internal 3.5" floppy drives with an external hard disc available as an add-on. Together with an on-board power supply the machine also incorporated an 80-column display and an RGB monitor connection

The main CPU unit had a flat-top to support a monitor and the detached keyboard also featured a separate numeric pad. Together with a parallel Centronics, RS232, light-pen and mouse port, a mother-card was supplied providing expansion boards to be fitted. At the time of announcement only three had been fully developed

The Dragon Beta board next to a Dragon 32 main board, notice the massive difference in size and hence complexity.

From the date on the boot ROM work was continuuing on the project right until the end of Dragon Data in the UK.

As of 28/7/04 the state of the Dragon Beta board is as follows.

  • Have power supply and floppy disk drives.
  • The board is not fully functional.
  • Boot and Character Gen ROMs dumped OK and appear coruption free.
  • The board has not been stored well and poor soldering to start with (from Dargon Data), is not helping.
  • The main CPU is running and is clocking Ok with data on the address and data busses.
  • The first few address lines are being dragged down.
  • Faulty octal buffer found on ROM address lines (due for replacement).
  • No software.
  • No Dragon 64 compatablie mode, BASIC etc. only an OS9 bootstrap.

Allegedly this board was rescued by Brian Moore (M.D.) on his way out the door as it was 'just laying about'.

If you can assist in getting this beaty up and running, circuit diagrams, notes, allot of patience and electronics knowledge :o), please do get in contact.

*Many* thanks to Simon Hardy for the help in securing this board.

UPDATE 10-5-05:

Some serious work on behalf of Phill Harvey-Smith with MESS has produced the first look into the working of the Dragon Beta with the boot screen.

Dragon Beta Boot Screen

I have also started taking steps to rebuild the Beta board, due it's poor condition it look like the only chance to get it in a good clean state is remove all the components to get a good clean start. Don't hold you breath this could take months or years!

UPDATE 12-11-05:

The machine is now rebuilt, sadly it is still refusing boot. Only the plus side it is actually running some code and setting up the PIA's but it gets no further. There appears to a fault in the memory mapping/addressing, so some reverse engineering is in progress to understand the process.

UPDATE 26-11-05:

It ROARS!!!!

The rebuilt circuit board, minus some I/O and the Fluke 9010A tester plugged in:

After *many* evenings work of tracing lines and reverse engineering the fault was tracked down to a solder 'splash' in the multiplexed address lines (for the RAM), with a timing flip flop. After this everything fell into place and the "OS-9 is loading" screen quickly popped up. Hastily refitted the the remaining I/O missing from the board, calibration of the floppy interface + time out to replace the hall sensors in the floppy drive (same fault as the Alpha drives). And.... it booted OS-9 first time!!

Plenty more to do, esp as they is complete lack of keyboard.

*Again* thanks to Phill, to his technical consultancy.

UPDATE 12-12-05:

Phill is burning the midnight oil on the lack of keyboard problem and getting the Beta emulation booting in MESS..... and it's paying off! It's actually booting in MESS and the keyboard is working..... Work continues, but it won't be long before it arrives in the official release of MESS.

The Beta earlier today in MESS

UPDATE 04-01-06:

The Beta got it's first run out on the highway, with the help of Phill's electronic magic. The reverse eng. has resulted in a fully functioning keyboard. The interface has been implemented in 74 logic chips to keep it athentic and if that wasn't enough Phill has also managed to allow a PC keyboard to be hooked in!

The prototype 74 logic chips interface, to allow the keyboard to be read with only 7 lines.

Archives own Dragon Beta shown.

Acknowledgments : David Linsley