archive.worldofdragon.org

rolfmichelsen wrote:

RoyCoates wrote:Both MM and JSW were written by playing/studying the spectrum version and then writing code to mimic what I saw

Now, this is impressive

Seconded! Graphics is one thing, but ports done in that way often get the behaviour "not quite right" (witness certain versions of Chuckie Egg), and MM/JSW both seemed spot on to me!

Is there anybody out there who has any information about the implementation of the FLEX filesystem? I've been playing around with a tool for manipulating Dragon filesystems from a PC, making it easy to move files between the PC and a Dragon emulator. This is somewhat similar to the MESS imgtool only with support for the Dragon filesystems. So far I have only been able to list the directory of the FLEX filesystem...

Look at the attached program if you want to have a look. Try something like "dst -fstype flex dir flex.vdk" from the command line to list the directory of a FLEX disk, or "dst help" for some idea about how to play with this. Beware, most functionality is currently buggy or might not perform exactly the function you believe it will. I'm working on this as I gradually get a better understanding of the different Dragon-related filesystems...

-- Rolf

RoyCoates wrote:

admin wrote:Likewise if you can help "Prime" with the Dragon Plus board I would be personally very greatful (its my board thats dead) - we need to get a dump of the prom so we can replicate it.

If the sucker powers up, you are welcome to borrow it.

One thing I feel obligated to point out, getting an image of the PROM will require me to desolder it from the Plus board to read it, there is of course a risk involved in this, if you are still happy for me to do this than thanks. I will of course take the upmost care, and as Simon can comfirm I do have reasonable equipment and a reasonable succes rate (helped in the repair of 2 Alphas, and the only working Beta) etc.

On the other hand if the sucker doesn't power up......I may be able to remady that, as in working on Simon's board, I have traced the circuit of the Plus.

Cheers.

Phill.

I can check my board to see if its soldered, and if not I have an EPROM programmer at work I can use to read it.

<Going to get it out of the garage now>

Is it IC22 you need to read? Mine is socketed and just a regular 2764.

dlinsley wrote:I can check my board to see if its soldered, and if not I have an EPROM programmer at work I can use to read it.

<Going to get it out of the garage now>

Is it IC22 you need to read? Mine is socketed and just a regular 2764.

Nope it's IC12 which should be a 82S147, it's a bipolar prom I think, alas my device programmer doesn't read it, but it's fairly easy to rig up an adapter board and read it as a 2716, you just get multiple copies of the data. Alas the one on Simon's board though it read I think is corrupt cirtainly the board doesn't work with it in.

Cheers.

Phill.

Yeah, soldered on this one too. Do you think rigging up an adaptor with a test clip would work in-circuit (without powering up the board)?

dlinsley wrote:Yeah, soldered on this one too. Do you think rigging up an adaptor with a test clip would work in-circuit (without powering up the board)?

Possibly, but then you have the other circuitry which is connected to the pins possibly loading the inputs / outputs and making them not reliable.

Also unless you disconnected the power connections between the chip and the rest of the board, you'd effectivly be powering it up anyways.......

Bottom line is the only reliable way of dumping is to desolder it. However I completely understand if people don't want to risk that.

Cheers.

Phill.

RoyCoates wrote:A brief aside: Wrt the TRS-80, what a lot of people didn't realise was that there was no access to Mathew's Model 4 or to the original Speccy code.

Both MM and JSW were written by playing/studying the spectrum version and then writing code to mimic what I saw. Graphics were generated by pausing the game, counting pixels, hand-converting (binary) pixels to byte values - and hand coding them in. It was horribly tedious and yet exciting at the same time.

I think each game took about 3 months of very long work-days.

Wow! I only just read this whilst searching for DragonPlus related threads. I always imagined something like a MM or JSW conversion was done by converting source code!

They weren't "conversions". Each was written completely from scratch.

I'd play the Spectrum version, then go and write code to make the Dragon do the same thing. I would often spend hours literally counting pixels to make sure the graphics were the same on both platforms.

And I've just realised, that after all these years - I'm often still doing much the same thing, only with aircraft avionics systems instead of games.

I need a change!

prime wrote:Are you the same Roy Coates that did the Dragon versions of Manic Miner / Jet Set Willy ?

... and don't forget "Beanstalker"! I spent quite a few hours on that one, too...