One chip MSX improvement project

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By KdL

Paragon (1408)

KdL's picture

08-11-2015, 02:23

sd_snatcher wrote:

@KdL

I just read the v3.3RC3 firmware source code, and noticed that the turbo blitter seems to be there, but it isn't assigned to any key combination. I would like to ask you to assign it to SHIFT+F12 so it can be easily enabled/disabled on the fly then.

If possible, I would like to suggest a feature: add an option to select if the 15KHz RGB mode will output "CSYNC + audio" or "HSYNC + VSYNC". The separate sync would allow the existing VGA->SCART adapters to be used.

I'm sorry, Shift+F12 is assigned to the Slot1 in my project.
The priority is not to add new features but improving the emulation.
Anyway I added your suggestion in todo list. Thanks.

By giuseve

Paladin (744)

giuseve's picture

23-11-2015, 19:20

Hi KDL (or have I to say CIAO ??)

I'm in the cue of the next ZEMMIX NEO from Brazil And I can't wait to have it on my desk.
If I understood correctly it will come with your Great Firmware.
And it will include SCC+ emulation and ESERAM and other stuff like these (Is it possible to read the whole list?)
My question is: COnsidering I own a MEGAFLASHROMSCC+SD with 512K Ram, is it possible to have an "alternative" firmware for ZEMMIX NEO?
I mean, considering I would already have the SCC would it possible to have on the Altera Chip the emulation of another kind of Music HW instead of the SCC?
I'm thinking about MSX-AUDIO with 256K of sample ram instead of SCC and ESERAM
Or better Moonsound !!
In that case my MSX would be very complete !!!

Is there a website about your work?
Is there a website (not in Japanese or Korean) to obtain more knowledge about OCM e ZNEO?

Regards !!!!

By RetroTechie

Paragon (1563)

RetroTechie's picture

24-11-2015, 13:37

giuseve wrote:

Is there a website about your work?

www.webalice.it/gnogni which re-directs to
gnogni.altervista.org

Quote:

I mean, considering I would already have the SCC would it possible to have on the Altera Chip the emulation of another kind of Music HW instead of the SCC?
I'm thinking about MSX-AUDIO with 256K of sample ram instead of SCC and ESERAM
Or better Moonsound !!

The 1chipMSX's (and thus Zemmix Neo's) FPGA is like 90+% used with the MSX and all its peripherals. That means: take out relatively simple SCC, and you still don't have room to add a more complex sound chip.

That is: if FPGA implementation for such a sound chip exists. Which afaik isn't the case for either Y8950 (MSX-Audio) or YMF278b (Moonsound/OPL4). Although it seems there is being worked on FPGA implementation of OPL3 (YMF262) to which OPL4 is partly compatible. So this might be in the future. For original 1chipMSX or Zemmix Neo, doesn't solve the "no space left on device" problem though... :-(

By AxelStone

Prophet (3055)

AxelStone's picture

23-12-2015, 22:18

KdL wrote:
sd_snatcher wrote:

@KdL

I just read the v3.3RC3 firmware source code, and noticed that the turbo blitter seems to be there, but it isn't assigned to any key combination. I would like to ask you to assign it to SHIFT+F12 so it can be easily enabled/disabled on the fly then.

If possible, I would like to suggest a feature: add an option to select if the 15KHz RGB mode will output "CSYNC + audio" or "HSYNC + VSYNC". The separate sync would allow the existing VGA->SCART adapters to be used.

I'm sorry, Shift+F12 is assigned to the Slot1 in my project.
The priority is not to add new features but improving the emulation.
Anyway I added your suggestion in todo list. Thanks.

I add to suggestion of @sd_snatcher. I've 2 standar VGA -> scart adapter and can't use any of them since the output is not standar (use of pin14 to audio). Should it be possible in next firmware version to standarize VGA -> Scart output? Acording to manuals it seems that in 3.1 version it worked as standar, may be?

Thanks :)

By sd_snatcher

Prophet (3473)

sd_snatcher's picture

24-12-2015, 03:34

KdL wrote:

I'm sorry, Shift+F12 is assigned to the Slot1 in my project.

What about CTRL+F12 then? Smile

By Grauw

Ascended (10074)

Grauw's picture

09-01-2016, 21:43

Grauw wrote:

I found a bug in the OCM line interrupts. Its VDP doesn’t generate line interrupts beyond line 192 / 212 (depending on the LN setting), whereas a real V99x8 does.

What I’m doing to encounter the issue is explained here.

I think the problem is this:

-- HSYNC INTERRUPT
HSYNCINT_N  <=  '1' WHEN( ( REG_R0_HSYNC_INT_EN = '0' ) OR ( ENAHSYNC = '0' ) )ELSE
                REQ_HSYNC_INT_N;

Specifically, the ENAHSYNC check:

IF( CLK21M'EVENT AND CLK21M = '1' )THEN
    IF( PREDOTCOUNTER_YP = "000000000" )THEN
        ENAHSYNC <= '1';
    ELSIF( PREWINDOW_Y = '0' )THEN
        ENAHSYNC <= '0';
    END IF;
END IF;

In vdp_ssg.vhd PREWINDOW_Y is set to 0 on line 192 or 212:

IF( PREDOTCOUNTER_YP_V = 0 ) THEN
    PREWINDOW_Y <= '1';
ELSIF(  ((REG_R9_Y_DOTS = '0') AND (PREDOTCOUNTER_YP_V = 192)) OR
        ((REG_R9_Y_DOTS = '1') AND (PREDOTCOUNTER_YP_V = 212)) )THEN
    PREWINDOW_Y <= '0';
    PREWINDOW_Y_SP <= '0';
END IF;

…which in turn temporarily disables line interrupts, however this is too soon.

Quoting openMSX source code on this temporary horizontal interrupt blackout, “No line interrupt will occur after next top border start”, if I understand that correctly this means at 60 Hz / 192 lines: at line 236, at 60 Hz / 212 lines: at line 246, at 50 Hz / 192 lines: at line 260, 50 Hz / 212 lines: at line 270 (going past the IL register range here).

By KdL

Paragon (1408)

KdL's picture

09-01-2016, 22:05

Thank you all for suggestions Smile

By sd_snatcher

Prophet (3473)

sd_snatcher's picture

10-01-2016, 13:53

@Grauw

I wonder how the overscan trick influences this interrupt generation. Does it allow for interrupts to be generated beyond line 255 because the VDP thinks the line value is lower?

By spl

Paragon (1470)

spl's picture

28-01-2016, 15:50

Hi Smile Any news about 1chipMSX core updates?

By Algorythms

Champion (287)

Algorythms's picture

03-02-2016, 10:05

@KdL

Hi, and thank you for all your great work with the OCM core!
A suggestion: Would it be possible to raise the ESE SCC+ ram to 2mb now that a couple of new games use more than 1mb?

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