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Atari coding BBS
| Re: Synclock & Loading from floppy |
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Posted by: calimero
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Nov,06.2012-16:05
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here you will find all info about ppera "spectrum512" video:
http://forum.8bitchip.info/software-17/high-color-video-playback-on-ste/
Petari: "400x200 is maybe possible. But let's solve some simpler things for beginning.
50 fps is too-too much. During playback, I load half of bitmap of next frame in first border period (bottom, then top), in second one second half of bitmap + audio (1KB) . There are some paddings, because must maintain whole sector loadings. Color data (same one) is loaded 2x in order, directly to shifter, and while it, data rate is not so critical, only that disk must not make pauses between sectors.
With 320x200, synced color loading during scanlines is a must, because there is only some 33% of time available for over 800KB/sec. With 320x160, you can load everything in RAM, and use normal hi-color code, because have almost 50% of time for loading."
regarding: "If we're going to take that route, how about plugging in a PC and have the ST send the data there to be displayed on a VGA graphic system? "
there is no much modification to ROM (for fast reading nothing; for fast writing: two wires):
"It is (ROM port) connected to CPU data and address bus directly - and reading speed is same as reading RAM.
... Typical code for transfer is: move.l (a0)+,(a1)+ ... repeat it as many data must be transferred.
... This way allows max 1600KB/sec
... With movem we can get more, about 1900KB/sec
... So, how then I achieved over 2MBsec ?
... First thing is: IDE port is alway on same address, and IDE self autoincrements data pointer, internally. So, we don't need to care about source address. Second came with need for fast write:
if we ensure that nothing will interfer with our code (interrupts disabled etc) we can open IDE port at every RAM access and write what is on data bus in that moment. Then simple:
move.l (a1),d0 will do the job, faster than way above - because no reading into CPU first."
...
http://forum.8bitchip.info/hardware-16/cartridge-port-ide-if-design-finished-(project-cata)/msg1064/#msg1064
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Posted by
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Date
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Synclock & Loading from floppy
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Defjam
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Nov,05.2012-18:12
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Re: Synclock & Loading from floppy
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evil
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Nov,05.2012-21:38
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Re: Synclock & Loading from floppy
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defjam
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Nov,06.2012-16:00
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Re: Synclock & Loading from floppy
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calimero
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Nov,06.2012-16:05
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Re: Synclock & Loading from floppy
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ggn
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Nov,06.2012-20:28
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Re: Synclock & Loading from floppy
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CiH
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Nov,05.2012-21:59
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Re: Synclock & Loading from floppy
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ggn
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Nov,06.2012-08:34
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Re: Synclock & Loading from floppy
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Leonard
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Nov,06.2012-03:12
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Re: Synclock & Loading from floppy
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Alien / ST-CNX
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Nov,13.2012-05:59
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Re: Synclock & Loading from floppy
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Petari
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Nov,13.2012-16:45
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Re: Synclock & Loading from floppy
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ggn
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Nov,13.2012-19:13
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Re: Synclock & Loading from floppy
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mikro
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Nov,13.2012-19:18
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Re: Synclock & Loading from floppy
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Petari
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Nov,14.2012-11:49
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Re: Synclock & Loading from floppy
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Mr. Styckx
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Nov,14.2012-16:37
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What's the anti-troll code?
That's your personal code to be able to add comments and messages on the dhs.nu site.
Don't have a code or forgot it? Fix it here.
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