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