Forums

Sega Master System / Mark III / Game Gear
SG-1000 / SC-3000 / SF-7000 / OMV
Home - Forums - Games - Scans - Maps - Cheats - Credits
Music - Videos - Development - Hacks - Translations - Homebrew

View topic - Snail.asm ...

Reply to topic
Author Message
  • Joined: 12 Jul 1999
  • Posts: 882
Reply with quote
Snail.asm ...
Post Posted: Mon Aug 02, 1999 9:40 am
Why does the timing seem to be rather shot?
It seems to speed up and slow down more often than my school's year 8 band.
To my understanding, you are timing it to the VBlank period (whatever that is)?
Isn't there a more reliable method for timing the note duration?
Doesn't the Z80 have an internal clock to which it measures things?
~unfnknblvbl
  View user's profile Send private message
Eric
  • Guest
Reply with quote
Post Posted: Mon Aug 02, 1999 4:08 pm
Quote
> Why does the timing seem to be rather shot?

I don't know. It runs fine (on Massage and BrSMS) on my computer. Each note should be exactly the same length.

Quote
> It seems to speed up and slow down more often than my school's year 8 band.
> To my understanding, you are timing it to the VBlank period (whatever that is)?

VBlank is an timing signal used to properly display the screen on a television. On the SMS it can generate an interrupt, referred to as the VBlank interrupt or VSync interrupt.

By definition this interrupt is triggered 60 times a second on NTSC (U.S., Japan) SMS units, and 50 times a second on PAL (European) SMS units.

Because this signal is measure in real time it is the best timing signal to use for music. I believe most commercial SMS games use this signal for basic timing as well.

Quote
> Isn't there a more reliable method for timing the note duration?

In my opinion, no.

Quote
> Doesn't the Z80 have an internal clock to which it measures things?

Yes, the Z80 clock. However, to use this I would need to write my own delay loops in Z80 code. This would really mess things up as different emulators may execute each intruction in the loop differently resulting in even more timing problems with the music.

Is anyone else having this problem?

Eric
 
Eric
  • Guest
Reply with quote
Post Posted: Mon Aug 02, 1999 4:09 pm
Quote
> Why does the timing seem to be rather shot?

I don't know. It runs fine (on Massage and BrSMS) on my computer. Each note should be exactly the same length.

Quote
> It seems to speed up and slow down more often than my school's year 8 band.
> To my understanding, you are timing it to the VBlank period (whatever that is)?

VBlank is an timing signal used to properly display the screen on a television. On the SMS it can generate an interrupt, referred to as the VBlank interrupt or VSync interrupt.

By definition this interrupt is triggered 60 times a second on NTSC (U.S., Japan) SMS units, and 50 times a second on PAL (European) SMS units.

Because this signal is measure in real time it is the best timing signal to use for music. I believe most commercial SMS games use this signal for basic timing as well.

Quote
> Isn't there a more reliable method for timing the note duration?

In my opinion, no.

Quote
> Doesn't the Z80 have an internal clock to which it measures things?

Yes, the Z80 clock. However, to use this I would need to write my own delay loops in Z80 code. This would really mess things up as different emulators may execute each intruction in the loop differently resulting in even more timing problems with the music.

Is anyone else having this problem?

Eric
 
Eric
  • Guest
Reply with quote
HTML mistake, read the post above instead.
Post Posted: Mon Aug 02, 1999 4:11 pm
This space intentionally left blank.
 
Reply to topic



Back to the top of this page

Back to SMS Power!