Search found 732 matches

by HardWareMan
Mon Jan 06, 2020 12:50 pm
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7653

Re: Cartridge slot questions

I suppose it would be nice to know what range the 32X outputs on the audio lines (though I heard reports that the 32X's output may be a bit too loud). It is the one piece of official hardware that makes use of it. Also the cartridges with YM2413 seem to use its output directly (?) so maybe looking ...
by HardWareMan
Mon Jan 06, 2020 4:55 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7653

Re: Cartridge slot questions

That still doesn't tell me what voltage range you should use to keep the audio signal in a "reasonable" range (I'm not a Mega Drive circuit expert :v), only that it's mixed as-is with the rest of the audio (my initial guess would be that the ideal range would be ±1V but honestly I could be wildly w...
by HardWareMan
Sun Jan 05, 2020 4:13 am
Forum: Hardware
Topic: Cartridge slot questions
Replies: 23
Views: 7653

Re: Cartridge slot questions

Image
by HardWareMan
Sun Dec 29, 2019 5:24 pm
Forum: Megadrive/Genesis
Topic: M68K Bus Control and Vdp
Replies: 25
Views: 6577

Re: M68K Bus Control and Vdp

It can be confirmed by a quick test but above notes suggest that when /ZTOV is asserted, IC5 simply copies VD15-VD8 to ZD0-ZD7 (and when /ZTOV is asserted, it copies ZD0-ZD7 to VD15-VD8 and VD7-VD0). It makes no difference on byte write since 68k duplicates VD7-VD0 on VD15-VD8 and on word writes, i...
by HardWareMan
Wed Dec 18, 2019 12:37 pm
Forum: Megadrive/Genesis
Topic: M68K Bus Control and Vdp
Replies: 25
Views: 6577

Re: M68K Bus Control and Vdp

IC5 315-5309 is used to unite the M68K and Z80 buses. It used ZA[7:0] and ZD[7:0] from Z80 side and VA[7:1] and VD[15:0] from M68K side. For setting mode for access through it used this set of control signals: nCAS0 , nLWR , nHL from M68K side and nZTOV , nVTOZ form bus arbiter IC4 315-5364 . So, u...
by HardWareMan
Fri Jun 21, 2019 7:23 am
Forum: Demos
Topic: Album of drawings 1.0 (Demo)
Replies: 1
Views: 2734

Re: Album of drawings 1.0 (Demo)

Why "key" and not "button"?
by HardWareMan
Tue Jun 04, 2019 10:29 am
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 18114

Re: Cart Design Questions

In terms on the devices I have on board, they are with their estimated power consumption: 1x SAM4S (30mA @ 3.3V) (50mA startup current needed) 1x Intel Max V CPLD (VCCIO 10mA @ 3.3V (40mA startup current), VCCINT ~10mA @ 1.8V) 1x EEPROM @ 50mA So in all, the load on the regulator for 5V->3.3V is 50...
by HardWareMan
Thu May 30, 2019 5:30 am
Forum: Demos
Topic: Misplaced
Replies: 1
Views: 3297

Misplaced

Recently I found the new game for MD/Genesis: Misplaced https://img.itch.zone/aW1hZ2UvNDI4OTA3LzIxNDQzNzQucG5n/347x500/DL9Xjh.png My name is Hara... Every day I start in the same way, I wake up on a small strange island that hovers somewhere in the clouds. And today one of these identical days... We...
by HardWareMan
Mon May 27, 2019 2:13 pm
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 18114

Re: Cart Design Questions

You guys mentioned earlier that /AS is not asserted for DMA, and that /CAS2 is asserted for DMA. But do you guys know if /CAS0 is also asserted for DMA? If /CAS0 is asserted for all accesses (68k, Z80 and VDP), then I can get the CPLD to listen using /CEO and /CAS0 and therefore have more time to g...
by HardWareMan
Tue May 21, 2019 7:09 am
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 19016

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

Sik wrote:
Sun May 19, 2019 5:29 pm
$A14xxx has the TMSS-related ports (on systems with TMSS, that is).
Systems without TMSS still don't assert !DTACK at those range.
TmEE co.(TM) wrote:
Mon May 20, 2019 9:49 pm
...but seems only A15xxx range is used by SVP outside normal stuff.
Ok, then it will be A16000...BFFFFF without !DTACK to use more or less freely.
by HardWareMan
Sun May 19, 2019 5:05 pm
Forum: Megadrive/Genesis
Topic: Cart Design Questions
Replies: 45
Views: 18114

Re: Cart Design Questions

It is better to use !CAS2. When it asserts (goes to zero) there is sure stable address in any cycle, include DMA. The only problem with it is you've got shorter access time.
by HardWareMan
Sun May 19, 2019 5:00 pm
Forum: Demos
Topic: MD-NICCC - a 3D Mega Drive experience by TiTAN
Replies: 56
Views: 19016

Re: MD-NICCC - a 3D Mega Drive experience by TiTAN

TmEE co.(TM) wrote:
Sat May 18, 2019 7:39 pm
It can only be used in ranges where VDP doesn't generate it for you such as 800000...9FFFFF. This area is used by 32X and SVP for example. You cannot forcibly override !DTACK since VDP actively drives it on most accesses.
There is also A14000...BFFFFF without !DTACK.
by HardWareMan
Sat May 11, 2019 5:11 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 43
Views: 18795

Re: I'm officially building a microcode-level 68000 core

Also I think we should make cycle and logic accurate 68000 model for FPGA.
by HardWareMan
Mon May 06, 2019 5:27 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 43
Views: 18795

Re: I'm officially building a microcode-level 68000 core

There's also a bit of a fondness for abbreviated variable and function names. Can anyone decipher what this means? bool n2388 = !(s.clk || s.berro || s.n1361 || s.n2735 || s.n2772 || s.n2781); Yeah, me neither. This is just 6NOR logic with those 6 "signals" as boolean variables. I think this is cam...
by HardWareMan
Tue Apr 30, 2019 5:47 pm
Forum: Mega/SegaCD
Topic: Questions on writing a new Mega CD emulator
Replies: 114
Views: 30602

Re: Questions on writing a new Mega CD emulator

We already discussed nIRQ frequency: http://gendev.spritesmind.net/forum/viewtopic.php?f=13&t=793&start=105#p31682 It's like a nIRQ not synced to any of signal. As I said before, this signal has 6,33ms period time slot. But it don't fire up at every slot (6,33ms), some slots a skipped (when drive co...