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OffTopic > Genesis games on the GBA/DS

#38910 - mariods - Fri Apr 01, 2005 11:05 pm

Could sega games be emulated on the gba in any way???

#38913 - Lupin - Fri Apr 01, 2005 11:58 pm

google "pocketSMS" or "DrSMS"
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#49929 - MegaRed - Wed Aug 03, 2005 6:59 pm

Forgive my bumping up of an old thread, but while DrSMS is a fantastic program (that I use quite often), is there any program set up to play Genesis games on the GBA?

Or hell, has anyone been able to port Sonic 1, 2 or 3K to GBA format?

#49932 - tepples - Wed Aug 03, 2005 8:05 pm

Sonic Advance 1-3 have different maps but mostly the same gameplay.
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#49936 - Dwedit - Wed Aug 03, 2005 8:22 pm

The Genesis is 3 times as powerful as the SNES. The GBA can barely emulate the SNES.
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#49979 - MegaRed - Thu Aug 04, 2005 4:49 am

Dwedit wrote:
The Genesis is 3 times as powerful as the SNES.
Wow, seriously?

I guess that closes that question then. I suppose we'll just have to wait for a DSGenesis program.

#54341 - dmgice - Sun Sep 18, 2005 2:48 pm

Dwedit wrote:
The Genesis is 3 times as powerful as the SNES. The GBA can barely emulate the SNES.


There is so much that is completely wrong with that statement that I have no idea where to even begin. Lemme try and seperate it into easier and TRUE statements.

The Genesis CPU has twice the MHZ speed of the SNES CPU, but featured less effects.

The CPU of the Genesis was inferior to the SNES CPU in terms of color output, sprite output, resolution, physics, rotation effects, etc. The SNES may have had a slightly slower CPU, but it had more girth.

Ports of SNES games to the Game Boy Advance are dependant on the skills of the people programming the port. When it comes to an emulator, it is entirely dependant on the person programming the emulator and their grasp of the workings of the system they are emulating.

The SNES and Genesis would both need specialized chips to be able to do some of the games on the Game Boy Advance. The Game Boy Advance can do -with hardware alone- what the SNES required the SFX, CS1, and SFX2 chips to do.

The Game Boy Advance can output more colors, and more sprites than the SNES and Genesis.

In short, the GBA could emulate the Genesis.
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#54351 - tepples - Sun Sep 18, 2005 6:26 pm

dmgice wrote:
The Genesis CPU has twice the MHZ speed of the SNES CPU, but featured less effects.

The Genesis CPU had more effects, including 16x16 hardware multiplication and 32/16 division instructions.

Quote:
The CPU of the Genesis was inferior to the SNES CPU in terms of color output, sprite output, resolution, physics, rotation effects, etc. The SNES may have had a slightly slower CPU, but it had more girth.

You're comparing PPUs, not CPUs. The PPU doesn't have to be emulated at full speed because it can be frameskipped. The CPU, on the other hand, is a lot harder to frameskip without affecting gameplay.

Quote:
The Game Boy Advance can output more colors, and more sprites than the SNES and Genesis.

Super NES had 32^3 = 32,768 colors. GBA and GBA SP have about 24^3 = 13824 usable colors due to the wide difference in gamma between the GBA display and the Super NES's sRGB display. Both the Super NES and GBA have 128 sprites, though the GBA does have more flexibility in sizing them. The Genesis can also output more pixels (320x224) than the GBA (240x160), and PocketNES style scaling works only in one direction at once.

Quote:
In short, the GBA could emulate the Genesis.

Write an MC68000 core that runs on the ARM at 1:1 cycle ratio, in order to save time for the Z80, and I'll believe you. Remember that when you're emulating a Genesis, you're not just emulating one system; you're emulating two because all the Sega Master System hardware is present and in use unlike in the GBA.

Or would you be happy with playing games at 1/4 their speed?
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#54448 - dmgice - Mon Sep 19, 2005 4:25 pm

Genesis Specs

CPU:
Motorola 68000 running at 7.61 MHz
1 MByte (8 Mbit) ROM Area
64 KByte RAM Area
Co-Processor: Z-80 running at 4 MHz (not included in Genesis 2 or 3 models)
Controls PSG (Programmable Sound Generator) & FM Chips
8 KBytes of dedicated Sound RAM
Graphics:
64 Simultaneous colors from a 512 color pallette
Pixel resolution: 320 x 224
VDP (Video Display Processor)
Dedicated video display processor
Controls playfield and sprites
64 KBytes of dedicated VRAM (Video RAM)
64 x 9-bits of CRAM (Color RAM)
3 Planes: 2 scrolling playfields, 1 sprite plane
Sound:
PSG (TI 76489 chip)
FM Chip (Yamaha YM 2612)
6-Channel Stereo
8 KBytes RAM
Signal/Noise Ratio: 14dB

SNES Specs

CPU 16-bit
Central Processing Unit (CPU)--65C816
Work RAM for CPU--128KB
Clock Speed-- 3.58 MHz
PPU 16-bit Picture Processing Unit
Video RAM for PPU (PPU)--64KB Max.
Colors Per Screen--256
Total Colors Available--32,768
Max. Screen Resolution--512 x 448 pixels
Max. Sprites Per Screen--128
Max. Sprites Per Line--32
Max. Sprite Size--64 x 64 pixels
Minimum Sprite Size--8 x 8 pixels
Scrolling--Horizontal, Vertical, Diagonal
APU 16-bit Audio Processing Unit (APU)
16-bit Pulse Code Modulator (PCM)--digital data converter
Sound channels--8
Audio Out Impedance Level--4 ohms

Those are from Overclock.org

Game Boy Advance Specs.
CPU
ARM Mode ARM7TDMI 32bit RISC CPU, 16.78MHz, 32bit opcodes
THUMB Mode ARM7TDMI 32bit RISC CPU, 16.78MHz, 16bit opcodes
Internal Memory
BIOS ROM 16 KBytes
Work RAM 288 KBytes (32K in-chip + 256K on-board)
VRAM 96 KBytes
OAM 1 KByte (128 OBJs 3x16bit, 32 OBJ-Rotation/Scalings 4x16bit)
Palette RAM 1 KByte (256 BG colors, 256 OBJ colors)
Video
Display 240x160 pixels (2.9 inch TFT color LCD display)
BG layers 4 background layers
BG types Tile/map based, or Bitmap based
BG colors 256 colors, or 16 colors/16 palettes, or 32,768 colors
OBJ colors 256 colors, or 16 colors/16 palettes
Effects Rotation/Scaling, alpha blending, fade-in/out, mosaic, window
OBJ size 12 types (in range 8x8 up to 64x64 dots)
OBJs/Screen max. 128 OBJs of any size (up to 64x64 dots each)
OBJs/Line max. 128 OBJs of 8x8 dots size (under best circumstances)
Priorities OBJ/OBJ: 0-127, OBJ/BG: 0-3, BG/BG: 0-3
Effects Rotation/Scaling, alpha blending, fade-in/out, mosaic, window
Sound
Analogue 4 channel CGB compatible
Digital 2 DMA sound channels

The GBA specs are from GBA Tek. Anyhow, I was looking at those and then I noticed something interesting.

In the specifications about the Genesis it has this bit: "Co-Processor: Z-80 running at 4 MHz (not included in Genesis 2 or 3 models)"

So, why would you have to emulate the Z80 which is only used for Master System compatability at the same time as the main Genesis chip? Especially since the Z80 was REMOVED from the Genesis 2 and Genesis 3. All of which, can play the more important games on the Genesis. Those being Streets of Rage, Sonic the Hedgehog, etc. I own a Genesis 3 model, and aside from one racing game which had a weird cartridge shape, the Genesis 3 plays everything. So, no. The Z80 is NOT in use, especially when it ISN'T there.

The GBA and GBA SP screens are GBR. The Micro and the Nintendo DS Top screen are RGB. So, the GBA can use it's full range of 32,768 colors. Just, it won't look good on the antique GBA, or GBA SP.

A trip to a Game Faqs.com documnet on the Genesis stated that the Z80 was used for sound only. Which is weird and I have not run into any audio glitches between the Genesis 1, and Genesis 3. What's odd, is that it stated that some Genesis games, like the Genesis version of Phantasy Star, ran exclusively on the Z80 and not on the 68,000.

Also, isn't the Motorola 68000 just a slightly modified version of the same chip used in the Atari ST. Commodore Amiga, and the Apple Lisa?

Also, I said the GBA could emulate the Genesis. I never said well. :-P
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#54455 - Miked0801 - Mon Sep 19, 2005 5:24 pm

When you said that the GBA could emulate the Genesis, it was implied that it would be a 100% emulation at full speed. The GBA does not have the cpu power needed to pull that off period. Hell, the GBA barely has the horsepower to pull off emulating an Intellevision console (and not near enough butons :)

You really don't get just how much is involved in pulling off emulation do you? Needless to say, it's one of the most complex and time consuming tasks a programmer could ever attempt. No thanks...

#54458 - Abscissa - Mon Sep 19, 2005 5:40 pm

dmgice wrote:
The GBA and GBA SP screens are GBR. The Micro and the Nintendo DS Top screen are RGB. So, the GBA can use it's full range of 32,768 colors. Just, it won't look good on the antique GBA, or GBA SP.

Just a technical note, the usable range of colors on the GBA vs the DS/Micro has nothing to do whether the pixels are BGR or RGB. It's because of the low intensity of the old GBA screen and the existence or lack of backlighting.
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#54488 - dmgice - Mon Sep 19, 2005 11:16 pm

Miked0801 wrote:
When you said that the GBA could emulate the Genesis, it was implied that it would be a 100% emulation at full speed. The GBA does not have the cpu power needed to pull that off period. Hell, the GBA barely has the horsepower to pull off emulating an Intellevision console (and not near enough butons :)

You really don't get just how much is involved in pulling off emulation do you? Needless to say, it's one of the most complex and time consuming tasks a programmer could ever attempt. No thanks...


Hell, the PSP can't even emulate the Genesis at full speed. I know how much is involved in emulation. :-P
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#54563 - FluBBa - Tue Sep 20, 2005 12:58 pm

For what it's worth...
The Z80 in the Genesis was not removed from the later versions as a lot of games used it to play music and some even rely on it to work at all.
My Z80 cpu core for SMSAdvance uses up allmost all of IWRAM, the M68k is even more advanced which means you'd probably have to run it from ROM as most of the EWRAM will be needed as RAM for the Genesis, not a pretty sight if you ask me.
The Genesis version of Phantasy Star is the exact same game as the SMS version just in a different cartridge, it runs in the SMS compatibility mode (on the Z80).
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