Could the Dragon use CoCo banked cartridges?

Hardware Hacking, Programming and Game Solutions/Cheats
pser1
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Joined: Sun Mar 25, 2012 7:32 pm
Location: Barcelona (SPAIN)

Re: Could the Dragon use CoCo banked cartridges?

Post by pser1 » Sun Apr 24, 2016 5:50 pm

Hi James,
I have made this test with two different cartridges.
The first one was ASTROBLAST, this started alright with POKE&HFFD6,0 (normal speed)
but strangely it hanged after POKE&HFFD7,0 (double speed)
Then I used STARSHIP CHAMELEON and this one worked flawlessly at both speeds, in
fact it is really very challenging at double speed!
There should be no problem issuing this double speed poke from the ROM and that way
the ROM code will be executed at double speed.
In fact you can seee that Basic executes at double speed without problems.

cheers
pere

jmk
Posts: 65
Joined: Fri Mar 20, 2009 1:12 am

Re: Could the Dragon use CoCo banked cartridges?

Post by jmk » Mon Apr 25, 2016 1:18 am

pser1 wrote:Hi James,
I have made this test with two different cartridges.
The first one was ASTROBLAST, this started alright with POKE&HFFD6,0 (normal speed)
but strangely it hanged after POKE&HFFD7,0 (double speed)
Then I used STARSHIP CHAMELEON and this one worked flawlessly at both speeds, in
fact it is really very challenging at double speed!
Thanks, Pere! It seems amazing that we get a double-speed computer, just by putting things in ROM?

pser1
Posts: 1205
Joined: Sun Mar 25, 2012 7:32 pm
Location: Barcelona (SPAIN)

Re: Could the Dragon use CoCo banked cartridges?

Post by pser1 » Mon Apr 25, 2016 11:13 am

you are right,James.
It is a pity that these machines weren't made to use the 2Mz capability
ROM, RAM and CPU could cope with it, but most probably VDG and SAM wouldn't,
but I am not sure about that point ...

About banking, I am pretty sure you can do it the way you prefer ...
using a switcher in RAM or calling a routine that is at the same place in all of
the banks to change between them.

cheers
pere

Alastair
Posts: 606
Joined: Fri Jul 18, 2008 11:33 pm

Re: Could the Dragon use CoCo banked cartridges?

Post by Alastair » Mon Apr 25, 2016 10:19 pm

A stupid question perhaps, but will a double-speed cartridge work on a Dragon that cannot take the double-speed poke itself?

jmk
Posts: 65
Joined: Fri Mar 20, 2009 1:12 am

Re: Could the Dragon use CoCo banked cartridges?

Post by jmk » Tue Apr 26, 2016 12:38 am

Alastair wrote:A stupid question perhaps, but will a double-speed cartridge work on a Dragon that cannot take the double-speed poke itself?
No, no, it's a very important question. One I would like to know the answer to myself!

Are there Dragons and CoCos that cannot handle POKE &HFFD7,0 to speed up ROM access? Whether they fail straight away or after a period of time?

If there are, then I could add an option to switch on double-speed mode, with a warning message. If not, then I could implement it without any option.

pser1
Posts: 1205
Joined: Sun Mar 25, 2012 7:32 pm
Location: Barcelona (SPAIN)

Re: Could the Dragon use CoCo banked cartridges?

Post by pser1 » Tue Apr 26, 2016 8:15 am

Hi James,
Unfortunately, there are some Dragons that don't like to roar at double speed.
It would be a nice idea to let the user choose the game speed ...
In fact some old Basic programs asked the user if the machine supported
that double speed.
You can read a lot on this subject in this thread:
viewtopic.php?f=8&t=338&hilit=speed+poke

cheers
pere

jmk
Posts: 65
Joined: Fri Mar 20, 2009 1:12 am

Re: Could the Dragon use CoCo banked cartridges?

Post by jmk » Tue Apr 26, 2016 10:07 pm

pser1 wrote:You can read a lot on this subject in this thread:
viewtopic.php?f=8&t=338&hilit=speed+poke
Thanks, Pere. That's a very informative thread. Unfortunately, I could not find it myself because of this unusual search response:
The following words in your search query were ignored because they are too common words: double speed.
You must specify at least one word to search for. Each word must consist of at least 3 characters and must not contain more than 14 characters excluding wildcards.
:shock:

Anyway, it seems that I should offer the option of double-speed ROM, but not RAM. But it is also possible that I could damage someone's machine by "allowing" them to run too fast... :?:

Should the cartridge come with a free CPU? :D

pser1
Posts: 1205
Joined: Sun Mar 25, 2012 7:32 pm
Location: Barcelona (SPAIN)

Re: Could the Dragon use CoCo banked cartridges?

Post by pser1 » Tue Apr 26, 2016 10:58 pm

hehe, many users will be happy to get a new and faster CPU with the cartridge, for sure!
and even more if it were an Hitachi HD63C09.

I don't know if the CPU could be damaged because of too much time working with this poke,
I think that most users do know if their machine supports well that speed POKE.
There were some Basic programs that asked the user if the machine could work with it, in
case anyone accepted that and the CPU could not, probably it simply hanged ... don't know for sure.
Fortunately my Dragons seem to be happy with both pokes (ROM and RAM)

cheers
pere

Alastair
Posts: 606
Joined: Fri Jul 18, 2008 11:33 pm

Re: Could the Dragon use CoCo banked cartridges?

Post by Alastair » Wed Apr 27, 2016 12:03 am

Thanks Pere, that's one of the threads I was going to link to, the other being viewtopic.php?f=5&t=42

James, the search function of this site is irritating to say the least, I searched for &HFFD7, at least that term isn't considered too common.

Regarding to what happens to Dragons, and I assume CoCos, that cannot run at double speed, the computer will run for a short time and then crash. I don't think it causes any damage, put it this way, since 1982/3 my D32 has crashed numerous times after being subjected to the double speed poke and it still works.

jmk
Posts: 65
Joined: Fri Mar 20, 2009 1:12 am

Re: Could the Dragon use CoCo banked cartridges?

Post by jmk » Wed Apr 27, 2016 8:04 pm

Alastair wrote:Thanks Pere, that's one of the threads I was going to link to, the other being viewtopic.php?f=5&t=42

James, the search function of this site is irritating to say the least, I searched for &HFFD7, at least that term isn't considered too common.

Regarding to what happens to Dragons, and I assume CoCos, that cannot run at double speed, the computer will run for a short time and then crash. I don't think it causes any damage, put it this way, since 1982/3 my D32 has crashed numerous times after being subjected to the double speed poke and it still works.
Thanks, Alistair, another good thread. I did a search for FFD7, which only shows up one thread. I didn't think to search for &HFFD7. :?

Also good to know that I'm not going to be liable for damaging any of those wonderful machines. :)

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