How to run the Dragon at double speed

Hardware Hacking, Programming and Game Solutions/Cheats
Commodore
Posts: 125
Joined: Thu Nov 20, 2014 1:37 am
Location: UK

Re: How to run the Dragon at double speed

Post by Commodore »

zephyr wrote:
Commodore wrote:With this one:

POKE65495,0:POKE65497,0:SOUND1,255":POKE65496,0:POKE65494,0

I got the tone but a garbled screen. It was non responsive to BREAK. After hammering the BREAK key for some time I got a garbled boot screen and silence was restored.
I pressed restore and the boot screen came back. I typed LIST, but the program was gone.
Hammering at the break key during these tests is not a good idea because you are preventing the test code from restoring the computer back to normal speed (POKE65496,0:POKE65494,0). The point of these tests is to see if the computer runs stable enough at double speed to complete the test and return to BASIC with no corruption (or as little as possible) of the RAM contents. Random characters left on the green text screen screen after the test has ended indicate that the RAM has been corrupted during the test. A garbled screen during the test is normal. It is an indication that the computer has crashed if you can still see the garbled screen after the test has finished (The computer should always be powered off and back on again on again if this happens).

The most useful double speed mode is what is known as the "address dependent" mode (Switch to double speed with POKE65495,0. Return to normal speed with POKE65494,0). In this mode the computer runs the processor at double speed only when running code in ROM (The BASIC interpreter at $8000 to $BFFF or Cartridge ROM at $C000 to $FEFF). This mode is useful for running BASIC programs and Cartridge based software at nearly double normal speed.
I've just re read this in more detail (a bit more peace and quiet!). How long should I let the test program run for?
zephyr
Posts: 1474
Joined: Mon Jul 21, 2008 1:18 am

Re: How to run the Dragon at double speed

Post by zephyr »

Try running the attached modified version of the game Flipper for about one hour. That should be enough time to test your D32's stability while running at A/D double speed (POKE65495,0).

Enter "CLOAD" to load the game.
Attachments
FLIPPERA.zip
(11.89 KiB) Downloaded 277 times
Commodore
Posts: 125
Joined: Thu Nov 20, 2014 1:37 am
Location: UK

Re: How to run the Dragon at double speed

Post by Commodore »

OK, thanks Zephyr.

Apologies in advance for the dumb question:

Do I need to input the POKE before loading, or is that in the code of the modified version of the game?

I'm hoping to do this on Tuesday. I'll certainly share the results.
zephyr
Posts: 1474
Joined: Mon Jul 21, 2008 1:18 am

Re: How to run the Dragon at double speed

Post by zephyr »

Commodore wrote: Do I need to input the POKE before loading, or is that in the code of the modified version of the game?
No. Always make sure that your Dragon is running at normal speed when loading or saving programs via cassette.

The double speed poke (POKE65495,0) has been added to the game code. It will switch to double speed automatically when you RUN the game.
Commodore
Posts: 125
Joined: Thu Nov 20, 2014 1:37 am
Location: UK

Re: How to run the Dragon at double speed

Post by Commodore »

Brilliant. Thanks for that Zephyr. Looking forward to trying it now.
Commodore
Posts: 125
Joined: Thu Nov 20, 2014 1:37 am
Location: UK

Re: How to run the Dragon at double speed

Post by Commodore »

Well I let the Dragon warm up for at least 30 minutes as prescribed, I then loaded up the game, and it worked. Which I guess is good news.

I have now had it running for 20 minutes, so I suppose that looks pretty promising, as it has been running without hitch.
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