Ok, well the chips are arranged on the raised patch board like in picture #1.
The motherboard sticker (M14863) is partially obscuring the text, I haven't moved it but I'm sure it's (c) Dragon Data Ltd rather than (c) Dragon Data Services Ltd (can sort of see the the 'L' of Ltd)
zephyr wrote:
(b) Is XL2 marked up as 14.218 or 14.31818 (MHz).
It's 14.31818 (MHz)
zephyr wrote:
(c) Is the UHF modulator (ASTEC) marked up as UM 1233, UM 1286, or UM 1287.
It's UM1286
Cheers for your help...
I'll get round to trying the double speed pokes again after it warms up at some point...
Thanks for checking. You have there one of the earliest Dragon's to come off the production line. Those early models suffer from very poor picture quality, and have a hardware problem which prevents the use of some semigraphic modes. If you buy another one, try to get one of the latest models fitted with Issue 6 motherboard, and 14.218 MHz crystal.
The latest Dragon's use a 14.218 MHz crystal to give a CPU frequency (/16) of 0.888625 MHz, a cycle time of 1.125334 us whereas the CoCo and original Dragon's use the NTSC standard frequency of 14.31818 MHz to give a CPU frequency of 0.894886 MHz or 1.117460 us per cycle. This was to reduce the harmonic interaction between the CPU frequency and that of the PAL crystal ( 4.433619 MHz ) used to generate the TV output, giving a 'cleaner' video signal. The later Dragon's therefore run approx 6261 CPU cycles per second slower than the CoCo and earlier Dragon's.
That first thread was a good read - I have to say that at first glance I think the picture looks quite good, I've got the machine plugged in via scart to a pretty modern HD telly and I was quite pleased with how it looks.
Might have to give it a proper go with some more games and see how I get on!
You have there one of the earliest Dragon's to come off the production line. Those early models suffer from very poor picture quality, and have a hardware problem which prevents the use of some semigraphic modes. If you buy another one, try to get one of the latest models fitted with Issue 6 motherboard, and 14.218 MHz crystal.