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Sega Mega Drive

From Sega Retro

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Fast facts on Sega Mega Drive
Manufacturer: Sega
Variants: Mega Drive 2, Genesis 3, Mega Jet, Nomad, Mega Tech, Mega Play, Amstrad Mega PC
Add-ons: Sega Mega-CD, Sega 32X, Mega Modem, Power Base Converter
Release Date RRP Code
Sega Mega Drive
JP
1988-10-29 ¥21,000 HAA-2510
Sega Mega Drive
US (NY/LA)
1989-08-14 $200.00 MK-1600
Sega Mega Drive
US (Nationwide)
1989-08 $200.00 MK-1600
Sega Mega Drive
UK
1990-09-14 £189.99[1][2] 1600-05
Sega Mega Drive
FR
1990-09 1890FF 1600-09
Sega Mega Drive
DE
1990  ?DM 1600-18
Sega Mega Drive
ES
1990  ?Pts 1600-06
Sega Mega Drive
IT
1990-11[3] 399.000[3]£ 1600-13
Sega Mega Drive
PT
199x  ?  ?
Sega Mega Drive
NL
1991 ƒ399 1600-20
Sega Mega Drive
AU
199x $ 1600-03
Sega Mega Drive
SE
1990 kr 1600-24
Sega Mega Drive
MX
19xx $?  ?
Sega Mega Drive
BR
1990-12 R$? 010300
Sega Mega Drive
KR
1990-05 ₩154,000  ?
Sega Mega Drive
IN
1995 ₹18,000  ?
Sega Mega Drive
TH
199x ฿?  ?

The Sega Mega Drive (メガドライブ), called the Sega Genesis in North America and Super Gam*Boy (수퍼겜보이) (later Super Aladdin Boy (수퍼알라딘 보이) in South Korea, is a cartridge-based video game console developed by Sega in 1988.

The Mega Drive is Sega's third home console, following the SG-1000 (including SG-1000 II) and the Sega Master System (Mark III). It was codenamed the Sega Mark V during development and is part of what is now known as the fourth generation of video game consoles.

The Mega Drive is Sega's most successful video game console, selling over 40 million units worldwide,[4] including more than 20 million in the United States, over 9 million in Western Europe, 3.58 million in Japan, and 3 million in Brazil.[5]

It has a software library consisting of more than one thousand games released for the system in total. As well as competing with Nintendo's Famicom (NES) and later Super Famicom (SNES) for market control, Sega also found itself fighting against NEC's TurboGrafx-16 (PC Engine in Japan), SNK's Neo Geo, the Atari Jaguar and numerous home computers in one of the biggest "console wars" of all time.

It had a cartridge enhancement chip, the Sega Virtua Processor, and two add-on consoles, the Sega CD and 32X. The Mega Drive would be succeeded by the Sega Saturn (released in 1994), and then the Sega Dreamcast (released in 1998).

Hardware

The Mega Drive was envisioned at the next technological step over other video game consoles available at the time. It is a "16-bit" machine, named after its use of a 16-bit CPU (in this case, the Motorola 68000), and was marketed as being superior to popular "8-bit" consoles dominating the market at the time, usually the Nintendo Entertainment System (NES) but sometimes its immediate predecessor, the Sega Master System. 16-bit CPUs had been gaining popularity since the mid-80s, were widely used in arcade machines, and were almost expected to be found in new home computers - it was therefore considered logical that the next "generation" of dedicated video game consoles should follow suit.

The Mega Drive builds on technology found in the Master System (and with adaptors, is fully backwards compatible), though as well as upping the technical specifications for more demanding gameplay, sound and graphics, makes a number of cruicial changes to the design of consoles which continue to this day. Firstly it added a third face button, C, to the (now ergonomically designed) control pad. The Mega Drive outputs sound in stereo, and makes an attempt to region lock games through software. Also, when utilising the right cables, the Mega Drive is natively able to produce a clearer image than its rivals (on top of its already higher resolution 320x240 display).

All Mega Drives ultilise a top-loading design (as opposed to the cumbersome VCR-style cartridge loading of the Western NES), while having removable controllers (unlike the Famicom). It was designed from day one to allow hardware expansions, and its use of dark plastic means that the "yellowing" of older systems (from bromine-based flame retardants reacting with oxygen) is less of an issue.

It was the most powerful console at the time of its release in 1988, surpassing the PC Engine (TurboGrafx-16), and it was not surpassed in power until the Neo Geo in 1990. The Mega Drive is also more powerful than the SNES, released in 1990, whereas the SNES has a larger color palette (see Blast Processing article for detailed technical comparison between the Mega Drive and SNES). Compared to home computers at the time, it was not as powerful as the Japan-exclusive Sharp X68000 (released 1987) or FM Towns (released 1989), but the Mega Drive was more powerful than home computers in the Western world, including the Amiga, with the Mega Drive having more powerful sprite and audio capabilities as well as tile capabilities. The Mega Drive displays eighty 15-color sprites at 32×32 pixels each, while the Amiga displays eight 3-color sprites at 8 pixels wide. The Mega Drive has up to 10 audio channels, compared to the Amiga's 4 audio channels.[6] The Mega Drive supports tilemap backgrounds, reducing processing, memory and bandwidth requirements by up to 64 times compared to the Amiga's bitmap backgrounds.[7] The Mega Drive also has comparable DMA blitting capabilities; the Amiga blitter's 1.7–3.5 MB/s DMA[8] is comparable to the Mega Drive VDP's 3.2–6.4 MB/s DMA, but with the Mega Drive's tile capabilities giving it a higher effective fillrate of up to 36 MPixels/s (see Blast Processing below).

Models

Main article: Mega Drive consoles.

Mega Drive

The original Mega Drive measures 28 cm×21.2 cm×7 cm. The top of the unit is split into two components: a circular emboss with the cartridge slot and a tagline (which was omitted on later versions), and a control panel containing the power and reset buttons and the volume slider for the headphones jack. Audio output through the original model was mono through the A/V port, while the headphone jack was used for stereo sound. A third DE-9 port on the back of the unit provided additional peripheral support, though was removed from later revisions.

Asian, Japanese and South Korean models have a cartridge locking mechanism which prevents cartridges from being removed when the power is on (which is why "Eastern" cartridges, as well as the Sonic & Knuckles cartridge and various others, have a cut-out on their left sides). Later runs included the TradeMark Security System, missing in early builds causing small compatibility issues, despite the feature having been planned early on.

Mega Drive 2

1993 saw this cost-reduced redesign (known as the Mega Drive II in Europe, and not explicitly referred to as anything other than "Genesis" in North America), at 22 cm×21.2 cm×5.9 cm, being introduced internationally. One of the major revisions from the original model was the removal of the headphones jack in favor of stereo output through a redesigned 9-pin A/V port. American and European models used a momentary switch for power while non-western models used a left-right switch. Furthermore, the audio mixing circuitry was modified, resulting in noticeably different quality audio output — here is a page with audio samples, provided by little-scale.

A common myth is that the Mega Drive 2 lacks a Z80 — the truth is that it lacks a Zilog Z80. During the Mega Drive's lifetime, Sega received various off-the-shelf chips from different manufacturers, and sometimes would rebrand chips as their own or make them themselves, which is what happened here (and which is why each Mega Drive has a different manufacturer for its 68000). If the Z80 was missing, most games would have no sound (or not all sound). In later revisions, the Z80 was integrated into a custom ASIC which also incorporated the major chips of the system.

Genesis 3

Main article: Genesis 3.
A Genesis 3.
The Genesis 3 was a small version manufactured by Majesco in 1998 for the American market, which they had been manufacturing for until then. It is much smaller than its predecessors and lacks all expansions and fixes memory controller bugs — both rendering some games unplayable and the Sega CD and 32X unusable.

Portables: Mega Jet and Nomad

Main articles: Sega Mega Jet and Sega Nomad.

The Mega Jet and Nomad were portable Mega Drive systems released near the middle/end of the system's lifetime. The Mega Jet, released in 1994, was originally designed for use on JAL airliners but was later released for Japanese consumers. The Mega Jet is a semi-portable system; the system has a built-in controller but requires an external power supply and a TV. The Nomad was a full portable in its own right, having an integrated screen and sound capabilities, in addition to a battery pack.

Arcade hardware: Mega Tech, Mega Play, and the System C

Main articles: Mega Tech, Mega Play, System C.

The Mega Drive hardware was adapted for arcade use several times over the course of its life. The Mega Tech and Mega Play allowed arcade operators to provide somewhat modified versions of popular Mega Drive games for arcade play — these systems use special cartridges containing games and players can choose from the games plugged into the system. The System C is a different board built from modified Mega Drive hardware, boasting improved color abilities and (in later revisions known collectively as the System C2) improved sample playback. The System C was primarily home to puzzle games — Columns and Puyo Puyo were released on this hardware.

Data East is also known to have licensed Mega Drive hardware for an arcade version of High Seas Havoc; not much is known about this board.

Mega-CD combos: JVC Wondermega/X'eye, Pioneer LaserActive, Sega Multi-Mega, and Aiwa Mega CD

Main articles: Wondermega, LaserActive, Sega Multi-Mega, Aiwa Mega CD.

Combination Mega Drive/Mega-CD units were developed over the course of the Mega-CD's lifetime. The Wondermega and LaserActive are standalone consoles; the LaserActive also plays LaserDiscs. The Multi-Mega is a portable audio CD player that can play Mega Drive and Mega-CD games when plugged in to wall power and a TV. The Aiwa Mega CD is a Mega Drive/Mega-CD packed into Aiwa's consumer-level portable CD stereos.

Computer combinations: Sega Teradrive, Amstrad Mega PC, al-Alamiah units

Main articles: Sega Teradrive, Amstrad Mega PC, Al-Alamiah AX-660, Al-Alamiah AX-990.

The Teradrive and Mega PC are combination Mega Drive/IBM-compatible PCs made for the Japanese and UK markets, respectively. The three Al-Alamiah computers are combination Mega Drive/MSX computers for the Arabic market.

Modern System-on-a-Chip compilations

A variety of companies now make licensed system-on-a-chip units in a variety of fashions that contain single-chip Mega Drive implementations and several licensed ROM images. TecToy-made SoaCs also contain several "new" MD games, however these are believed to be — and likely are — Java 2 Mobile Edition games running on additional hardware. For a full list of SoaCs, see the template at the bottom of the page.

Cartridges

Main article: Sega Mega Drive cartridges.

Technical specifications

Processors

  • Main CPU: Motorola 68000
    • Clock rate: 7.670453 MHz (NTSC), 7.600489 MHz (PAL)
    • The 68000 has a 24‑bit address space, allowing access to up to 16 MB of memory. Sega's memory map for the Mega Drive allowed games to be up to 4 MB without the use of a memory mapper; games that tried to go up to 10 MB would find their memory maps crushed by the Sega CD (which took the second 4 MB block) and Sega 32X (which took 2 MB of the third 4 MB block). All devices are memory mapped.
      • Games using save memory also needed to have the memory in the cartridge map; larger games, such as Phantasy Star IV, used a mapper to swap out cart space for SRAM during a save.
    • Instruction set: 16‑bit and 32‑bit CISC instructions
    • Data bus width: 32-bit internal,[11] 16‑bit external[12]
    • External data bus clock rate: 5 MHz[13] (10 MB/s external data bus access bandwidth)
    • Arithmetic logic units: 16-bit data ALU, 32-bit address ALU (2x 16-bit ALU)[14]
  • Sound CPU: Zilog Z80
    • Clock rate: 3.579545 MHz (NTSC), 3.546894 MHz (PAL)
    • Some games did not use the Z80, other games used it only for sample playback, but most used it for sound processing
    • 8 KB program RAM which the 68000 and the Z80 can freely write to (though the 68000 must request the Z80 bus)
    • Can access 32 KB of the 68000 memory map at once (while it should be used for accessing the cartridge, setting the bank register elsewhere can work on some hardware)
    • Instruction set: 8‑bit and 16‑bit instructions
    • Data bus width: 8‑bit
  • CPU instruction performance: 1.861363 MIPS (NTSC), 1.844386 MIPS (PAL)[15]
    • 68000 performance: 1.342329 MIPS (NTSC), 1.330086 MIPS (PAL)
    • Z80 performance: 0.519034 MIPS (NTSC), 0.5143 MIPS (PAL)

Sound

  • FM sound chip: Yamaha YM2612, clocked at the 68000 clock speed (7.670453 MHz in NTSC, 7.600489 MHz in PAL)
    • 6 channels of FM synthesis, Operator Type‑N
      • The third channel can enter a Special Mode, or multifrequency mode, where each individual operator has a different frequency
      • The sixth channel can enter a DAC mode where the sound program constantly streams 8‑bit unsigned PCM data to mix directly into the output waveform
    • 1 sine wave LFO (low frequency oscillator) channel
    • Mapped to the Z80 address space — 68000 must request the Z80 bus to use
    • Some Mega Drive 2 systems actually use the core from the chip's CMOS equivalent, the YM3438
    • IRQ interrupt capabilities: IRQ2 sound interrupt[18]
  • PSG sound chip: Sega PSG (SN76496),[19] clocked at the Z80 clock speed (3.579545 MHz in NTSC, 3.546894 MHz in PAL) and built into the VDP — same as with the Master System
    • Based on TI SN76489
    • 4 audio channels: Three channels of pure square wave tones, and one noise channel
      • The noise channel can play either white noise or "periodic noise" either at one of three preset frequencies or using the frequency of the third tone channel (consequently, that channel will be mute)
    • Can be freely accessed by both the 68000 through the VDP and the Z80 through its memory map
  • The cartridge connector has two pins which allow stereo sound mixing directly from cart. No game used this, however, but the 32X uses it for its PWM audio
  • The Mega Drive 1 has mono audio output from the TV output and stereo output from a built‑in headphone jack, plus a built‑in volume control. Future models drop the headphone jack and do stereo output from the TV output

Graphics

  • GPU chipset:
  • Screen resolutions:
    • Progressive scan resolutions:
      • NTSC: 320×224, 256×224
      • PAL: 320×224, 256×224, 320×240, 256×240
    • Interlaced resolutions:
      • NTSC: 320×448, 256×448
      • PAL: 320×448, 256×448, 320×480, 256×480
      • Note: "Interlaced mode" doubles the height of all resolutions; it was used by some games, such as Sonic 2 for two‑player mode.
  • Overscan resolutions:
  • Tilemap resolutions: 256×256 to 512×512 and 1024×256
  • Refresh rate: 59.92274 Hz (NTSC), 50.31974 Hz (PAL)
    • Maximum frame rate: 59.92274 frames/sec (NTSC), 50.31974 frames/sec (PAL)
  • Four graphics planes: two tile planes (just a grid of tiles), "window" tile plane (cannot be transparent), sprite plane
  • Color palette:[35]
    • Standard: 512 colors (9-bit RGB)
    • Shadow/Highlight mode: 1536 colors
  • Colors on screen:[35][31]
    • Standard: 61–64 colors
    • Shadow/Highlight mode: 183–192 colors
    • Mid‑frame palette swap: 75–256 colors (see Blast Processing below)
    • Direct color mode: 256–512 colors (see Blast Processing below)
  • Colors per pixel: 16 colors (4‑bit)Media:GenesisTechnicalOverview.pdf[23]
    • Mid‑frame palette swap: 16 colors (4-bit) to 256 colors (8-bit)
    • Direct color mode: 256 colors (8-bit) to 512 colors (9-bit)
  • Shadow/Highlight mode: Hardware lighting,[35] shadow generation (matching each character's shape),[30] triples color palette and colors on screen, increases colors per tile
  • Video RAM: 64.226563 KB (65,768 bytes)
    • 64 KB VRAM (Dual-Port VRAM) — used to store graphics tiles, mappings for all layers, and horizontal scrollingMedia:GenesisTechnicalOverview.pdf[36]
      • Scroll A Pattern Table: 2 KB (256x256) to 8 KB (512x512, 1024x256) for background tilemap plane A
      • Scroll B Pattern Table: 2 KB (256x256) to 8 KB (512x512, 1024x256) for background tilemap plane B
      • Window Pattern Name Table: 2 KB (256x224, 256x240) to 4 KB (320x224, 320x240) for static window plane
      • H Scroll Data Table: 1 KB for horizontal scrolling
      • Sprite Attribute Table: 512 bytes (256x224, 256x240) to 1 KB (320x224, 320x240) for sprite attributes
      • Pattern Generator Table: 2 KB to 56.5 KB for background tiles (64 to 1808 tiles, 32 KB per tile)
      • Sprite Generator Table: Up to 40 KB for sprite tiles (up to 1280 tiles, 32 KB per tile)
      • SAM buffer: 256 bytes separate cache within VRAM chips, for sending continuous stream of video screen refresh data to VDP while it reads/writes VRAM
    • VDP internal cache: 232 bytes
      • 64 9‑bit words (72 bytes) of internal CRAM (Color RAM) — used to store the color palette
        • 64 colors split into four 16‑color lines; each tile can be drawn with one of these four color lines
        • The first color in each line is transparent and any color of the entire palette can be used as a "background color" (when no pixels are drawn at a location); consequently the Mega Drive can display 61 colors on screen at once (unless raster effects or the Shadow/Highlight modes are used, in which case this number increases depending on the extent used)
        • Colors are 9‑bit RGB with 3 bits per color component, allowing for 512 colors
        • Shadow/Highlight modes increase color gamut
      • 80 bytes internal VSRAM (Vertical Scrolling RAM) — used for vertical scrolling (10‑bit words, up to 20 different vertical scroll values for each of the two scrolling playfields)Media:GenesisTechnicalOverview.pdf[17]
      • 80 bytes internal sprite buffer — 8 bytes per sprite[37][38]
  • Other features: Semi‑transparency, FIFO memory circuit design, read/write of one line buffer method for drawing[30]

Blast Processing

See Blast processing for more details and technical comparison with SNES

The term Blast Processing was primarily a reference to the Mega Drive VDP graphics processor's powerful DMA controller that could handle DMA (direct memory access) operations at much faster speeds than the Super Nintendo.[39] The Mega Drive could write to VRAM during active display and VBlank,Media:GenesisTechnicalOverview.pdf[17] and had a faster memory bandwidth than the SNES. The quicker DMA transfer rates and bandwidth gave the Mega Drive a faster performance than the SNES,[40] and helped give the Mega Drive a higher fillrate, higher gameplay resolution, faster parallax scrolling, fast data blitting, and high frame-rate with many moving objects on screen, and allowed it to display more unique tiles (background and sprite tiles) and large sprites (32×32 and higher) on screen, and quickly transfer more unique tiles and large sprites (16×16 and higher) on screen.

The Mega Drive's DMA capabilities also helped give it more flexibility, allowing the hardware to be programmed in various different ways. With DMA programming, it could replicate some of the Super Nintendo's hardware features, such as larger 64×64 sprites (combining 32×32 sprites), background scaling and rotation (like the Sega X Board and Mode 7), and direct color (increasing colors on screen). Other DMA programmable capabilities of the Mega Drive include mid-frame palette swaps (increasing colors per scanline), sprite scaling and rotation, ray casting, bitmap framebuffers, and 3D polygon graphics; the base Mega Drive hardware (without needing any enhancement chips) could render 3D polygons with a performance comparable to the Super Nintendo's optional Super FX enhancement chip,[41][42] which itself is significantly outperformed by the Mega Drive's optional Sega Virtua Processor enhancement chip.

  • VRAM bandwidth: 11.764705 MB/s (NTSC), 8.333333 MB/s (PAL) (see Memory below)Media:GenesisTechnicalOverview.pdf[43]Media:GenesisTechnicalOverview.pdf[27]
    • DMA transfer rate: 3.21845 MB/s, 205 bytes per scanline
    • DMA transfer per frame: 53.71 KB (NTSC), 63.96 KB (PAL)
    • DMA transfer per frame during active display: 205 bytes per VBlank scanline, 18 bytes per active display scanline, 11.822 KB (NTSC), 24.122 KB (PAL)
    • DMA transfer rate during active display: 708.406 KB/s (NTSC), 1.213812 MB/s (PAL)
  • CRAM/VSRAM cache bandwidth: 26.846588 MB/s (NTSC), 26.601712 MB/s (PAL) (see Memory below)Media:GenesisTechnicalOverview.pdf[43]Media:GenesisTechnicalOverview.pdf[27]
    • DMA transfer rate: 6.4369 MB/s, 410 bytes per scanline
    • DMA transfer per frame: 107.42 KB (NTSC), 127.92 KB (PAL)
    • DMA transfer per frame during active display: 410 bytes per VBlank scanline, 36 bytes per active display scanline, 23.644 KB (NTSC), 48.244 KB (PAL), 47.58 KB (NTSC), 68.08 KB (PAL)
    • DMA transfer rate during active display: 1.416813 MB/s (NTSC), 2.427625 MB/s (PAL)
  • Pixel fillrate: 6.934358 MPixels/s (NTSC), 6.650428 MPixels/s (PAL)
    • Write fillrate: 6.4369 MPixels/s, 410 pixels per scanline
    • Write fillrate during active display: 1.416813 MPixels/s (NTSC), 2.427625 MPixels/s (PAL)
  • Tile fillrate: 1808 tiles per frame,Media:GenesisTechnicalOverview.pdf[28] 108,340 tiles/sec (NTSC), 90,978 tiles/sec (PAL)
    • Texel fillrate: 115,712 texels (1808x 8×8 tiles) per frame, 6.934358 MTexels/s (NTSC), 5.822598 MTexels/s (PAL)
    • Tile transfer per frame during active display: 369 tiles (NTSC), 753 tiles (PAL)
  • Sprite fillrate: 80 sprites per frame, 4793 sprites/sec (NTSC), 4025 sprites/sec (PAL)
    • Sprite texel fillrate: 320 texels per scanline, 81,920 texels (80× 32×32 sprites) per frame,[35] 4.90887 MTexels/s (NTSC), 4.122193 MTexels/s (PAL)
    • Sprite tile filrrate: 1280 sprite tiles (80x 32×32 sprites) per frame, 76,701 sprite tiles/sec (NTSC), 64,409 sprite tiles/sec (PAL)
    • Sprite display per frame: 80 sprites (8×8 to 32×32), 20 sprites (64×64), 4 sprites (128×128)
      • Sprite display per scanline: 20 sprites (8×8 to 16×16), 13 sprites (24×24), 10 sprites (32×32), 5 sprites (64×64)
    • Sprite transfer per frame during active display:
      • NTSC: 80 sprites (8×8 to 24×24), 23 sprites (32×32), 5 sprites (64×64)
      • PAL: 80 sprites (8×8 to 24×24), 47 sprites (32×32), 11 sprites (64×64)
  • Effective fillrate: 2 tilemaps (256×256 to 512×512), 80 sprites (8×8 to 32×32), 60 FPS
    • Effective tile fillrate: 1808–9472 tiles per frame, 108,340–567,588 tiles/sec
    • Effective pixel fillrate: 115,712–606,208 pixels per frame, 6.934358–36.325644 MPixels/s
  • Mid-frame palette swap: Can use DMA to change color while drawing each scanline, sending more data to the VDP and more colors to the video DAC[44][30]
    • Colors on screen: 75 colors (Sonic 2) to 256 colors (static images)
    • Colors per pixel: 16 colors (4-bit) to 256 colors (8-bit)
  • Direct color mode: Can use DMA to reprogram CRAM from a color palette to a direct color display[31]
    • Colors on screen: 256 colors (8-bit) to 512 colors (9-bit)
    • Colors per pixel: 256 colors (8-bit) to 512 colors (9-bit)
    • Resolutions: 160×224, 128×224
  • Programmable resolutions:
    • Display resolutions: 128×160 to 256×160, 128×224 to 160×224
    • Background tilemap planes: 128×160 to 768×512[45]
    • Bitmap framebuffer:
      • Single buffering: 128×160 to 512×256 and 320×408
      • Double buffering: 128×160 to 256×256 and 320×204
  • 3D polygon graphics: Capable of 3D polygons with stock Mega Drive hardware (without needing enhancement chips), can use DMA to render bitmap framebuffer (double-buffered) that displays 3D polygons[41][46]
    • Geometry transformation: 10,000 vertices/sec, 500 vertices per frame
    • Geometry processing: 3000 polygons/sec, 150 polygons per frame
    • Frame rate: 20–30 frames/sec (256×160)[42]
    • Flat-shaded rendering: 1600 polygons/sec, 120 polygons per frame[42][47]
    • Texture-mapped rendering: 150 polygons/sec, 15 polygons per frame[48]
  • Other DMA programmable capabilities: Scaling and rotation (like Sega X Board and Mode 7),[49][50] ray casting
  • Optional cartridge enhancement chip: Sega Virtua Processor (only used in Virtua Racing), enhances Mega Drive's 3D polygon performance to 9000 polygons/sec, along with higher memory, bandwidth, fillrate, framebuffer resolution and frame rate

Memory

Configuration

Bandwidth

  • System RAM bandwidth: 25.321322 MB/s (NTSC), 21.88995 MB/s (PAL)
    • Main RAM: 10.526314 MB/s (16-bit, 5.263157 MHz)
    • VRAM: 11.764705 MB/s (NTSC), 8.333333 MB/s (PAL)
      • FPM DRAM: 11.764705 MB/s (NTSC), 8.333333 MB/s (PAL), 8 MB/s (when reading SAM)
      • SAM buffer cache: 13.423294 MB/s (NTSC), 13.300856 MB/s (PAL)
    • Audio RAM: 3.030303 MB/s (8-bit, 3.030303 MHz)
  • Cartridge ROM bandwidth: 10 MB/s (most cartridges), 15.200978–15.340906 MB/s (some cartridges)
  • Internal processor bandwidth:
    • 68000 internal bus: 30.681812 MB/s (NTSC, 32-bit, 7.600489 MHz), 30.401956 MB/s (PAL, 32-bit, 7.600489 MHz)
    • Z80 internal bus: 3.579545 MB/s (NTSC), 3.546894 MB/s (PAL)
    • VDP internal RAM cache: 26.846588 MB/s (NTSC, 16-bit, 13.423294 MHz), 26.601712 MB/s (PAL, 16-bit, 13.423294 MHz)

Memory map

Mega Drive Memory Map
Start End Size Description
$000000 $3FFFFF $400000 ROM Cartridge
$400000 $7FFFFF $400000 Expansion Port Area (used by the Sega CD)
$800000 $9FFFFF $200000 Unallocated (used by the Sega 32X)
$A00000 $A0FFFF $10000 Z80 Memory
$A10000 $A10FFF only various meaningful System registers
$A11000 $A11FFF only $A11100 and $A11200 meaningful Z80 control (/BUSREQ and /RESET lines)
$A12000 $AFFFFF only several meaningful Assorted registers
$B00000 $BFFFFF $100000 Unallocated
$C00000 $DFFFFF $1F; mirrored VDP
$E00000 $FFFFFF $10000; mirrored Work RAM (games usually only use the uppermost mirror, at $FF0000)

Input

  • Controller input: Two male DE‑9 controller ports; one female DE‑9 expansion port (early MD1s only)
    • Controller ports support two modes: parallel and serial
    • Parallel supports 7‑bit bidirectional, with the console setting the direction of each bit.
    • Parallel also supports optional active‑low interrupts on the TH line. (mapped to 68000 IRQ 2)
    • Serial mode supports up to 4800 bps. (used by the Mega Modem on port 3)
  • Expansion port: Used for Sega CD.
    • Provides access to /FDC ($A120xx) and /DISK to indicate Sega CD presence.
    • Maps Sega CD PRG RAM to $000000 when no cartridge is present, $400000 otherwise.

History

Main article: History of the Sega Mega Drive.

Games

Main article: List of Mega Drive games.

Launch titles

A Japanese Sega Mega Drive (Model 1) overloaded with add-ons including the Sega Mega-CD (Model 1), Sega 32X, Remote Arcade System and Mega-CD Karaoke.

Japan

North America

Europe

Magazine articles

Main article: Sega Mega Drive/Magazine articles.

Promotional material

Print advertisements

GamePro US 003.pdfGamePro US 003.pdf

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GamePro (US) #3: "September/October 1989" (1989-xx-xx)
also published in:













  • GamePro (US) #4: "November 1989" (1989-xx-xx)[71]













  • GamePro (US) #5: "December 1989" (1989-xx-xx)[72]

GamePlayers US 0105.pdfGamePlayers US 0105.pdf

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Game Players (US) Vol. 1 No. 5 "November 1989" (1989-xx-xx)
also published in:













  • VideoGames & Computer Entertainment (US) #11: "December 1989" (1989-xx-xx)[73]













  • Game Players (US) Vol. 1 No. 6 "December 1989" (1989-xx-xx)[74]

EGM US 027.pdfEGM US 027.pdf

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Electronic Gaming Monthly (US) #27: "October 1991" (1991-xx-xx)

ACE UK 37.pdfACE UK 37.pdf

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ACE (UK) #37: "October 1990" (1990-xx-xx)
also published in:













  • Computer & Video Games (UK) #107: "October 1990" (1990-09-16)[75]

CVG UK 108.pdfCVG UK 108.pdf

Print advert in














Computer & Video Games (UK) #108: "November 1990" (1990-10-16)
also published in:













  • ACE (UK) #38: "November 1990" (1990-xx-xx)[76]

SegaPower UK 13.pdfSegaPower UK 13.pdf

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Sega Power (UK) #13: "December 1990" (1990-xx-xx)
also published in:













  • ACE (UK) #39: "December 1990" (1990-xx-xx)[77]













  • Computer & Video Games (UK) #109: "December 1990" (1990-11-16)[78]

SegaPower UK 14.pdfSegaPower UK 14.pdf

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Sega Power (UK) #14: "January 1991" (199x-xx-xx)
also published in:













  • Raze (UK) #3: "January 1991" (1990-11-29)[79]













  • Computer & Video Games (UK) #110: "January 1991" (1990-12-15)[80]













  • Raze (UK) #4: "February 1991" (1991-12-20)[81]













  • Raze (UK) #5: "March 1991" (1991-01-31)[82]

CVG UK 111.pdf

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Computer & Video Games (UK) #111: "February 1991" (1991-01-16)

CVG UK 113.pdf

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Computer & Video Games (UK) #113: "April 1991" (1991-03-16)
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  • Computer & Video Games (UK) #114: "May 1991" (1991-04-14)[83]

CVG UK 122.pdfCVG UK 122.pdfCVG UK 122.pdfCVG UK 122.pdf

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Computer & Video Games (UK) #122: "January 1992" (1991-12-15)

CVG UK 126.pdfCVG UK 126.pdf

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Computer & Video Games (UK) #126: "May 1992" (1992-04-15)

PlayerOne FR 001.pdfPlayerOne FR 001.pdf

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Player One (FR) #1: "Septembre 1990" (1990-xx-xx)
also published in:













  • Joystick (FR) #9: "Octobre 1990" (1990-xx-xx)[84]

Joystick FR 027.pdfJoystick FR 027.pdfJoystick FR 027.pdfJoystick FR 027.pdf

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Joystick (FR) #27: "Mai 1992" (1992-xx-xx)
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  • Joystick (FR) #29: "Juillet/Août 1992" (1992-xx-xx)[85]













  • Joypad (FR) #9: "Juin 1992" (1992-xx-xx)[86]

PowerPlay DE 031.pdfPowerPlay DE 031.pdf

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Power Play (DE) #10/90 (1990-09-14)

PowerPlay DE 033.pdf

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Power Play (DE) #12/90 (1990-11-16)
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  • Power Play (DE) #2/91 (1991-01-18)[87]

Gamers DE 1992-01.pdf

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Gamers (DE) #1/92: "Februar/März 1992" (1992-xx-xx)

VideoGames DE 1992-11.pdf

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Video Games (DE) #11/92 (1992-10-28)

HobbyConsolas ES 002.pdfHobbyConsolas ES 002.pdfHobbyConsolas ES 002.pdf

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Hobby Consolas (ES) #2: "Noviembre 1991" (1991-xx-xx)

Micromania ES 056.pdfMicromania ES 056.pdf

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MicroManía (ES) #56: "Enero 1993" (199x-xx-xx)
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  • MicroManía (ES) #57: "Febrero 1993" (1993-xx-xx)[88]

Micromania ES 060.pdfMicromania ES 060.pdfMicromania ES 060.pdf

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MicroManía (ES) #60: "Mayo 1993" (1993-xx-xx)

Micromania ES 061.pdfMicromania ES 061.pdf

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MicroManía (ES) #61: "Junio 1993" (1993-xx-xx)

HobbyConsolas ES 037.pdfHobbyConsolas ES 037.pdf

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Hobby Consolas (ES) #37: "Octubre 1994" (1994-xx-xx)

Micromania ES 068.pdfMicromania ES 068.pdf

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MicroManía (ES) #68: "Enero 1994" (199x-xx-xx)

K IT 22.pdf

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K (IT) #22: "Novembre 1990" (1990-xx-xx)
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  • K (IT) #23: "Dicembre 1990" (1990-xx-xx)[89]













  • Guida Video Giochi (IT) #16: "Novembre 1990" (1990-xx-xx)[90]













  • Guida Video Giochi (IT) #17: "Dicembre 1990" (1990-xx-xx)[91]

K IT 24.pdf

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K (IT) #24: "Gennaio 1991" (199x-xx-xx)
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  • K (IT) #25: "Febbraio 1991" (199x-xx-xx)[92]













  • K (IT) #26: "Marzo 1991" (1991-xx-xx)[93]

K IT 27.pdf

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K (IT) #27: "Aprile 1991" (1991-xx-xx)

MegaForce PT 01.pdfMegaForce PT 01.pdf

Print advert in Mega Force (PT) #1: "Junho 1993" (1993-xx-xx)

MegaForce PT 01.pdf

Print advert in Mega Force (PT) #1: "Junho 1993" (1993-xx-xx)

MegaForce PT 03.pdfMegaForce PT 03.pdf

Print advert in Mega Force (PT) #3: "Agosto 1993" (1993-xx-xx)
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SegaForce SE 1992 01.pdf

Print advert in Sega Force (SE) #1/92 (1992-xx-xx)
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Retailers

SegaVisions US 01.pdf

Toys 'R' Us print advert in














Sega Visions (US) #1: "June/July 1990" (1990-xx-xx)

SegaVisions US 01.pdf

Kay-Bee print advert in














Sega Visions (US) #1: "June/July 1990" (1990-xx-xx)

SegaVisions US 09.pdf

Sears print advert in














Sega Visions (US) #9: "August/September 1992" (1992-xx-xx)
also published in:













  • Sega Visions (US) #10: "November/December 1992" (1992-xx-xx)[98]













  • Electronic Gaming Monthly (US) 1993 Video Game Buyer's Guide (199x-xx-xx)[99]













  • Sega Visions (US) #11: "February/March 1993" (199x-xx-xx)[100]

Pamphlets

Television advertisements

Artwork

References

  1. File:CVG UK 106.pdf, page 13
  2. File:ACE UK 37.pdf, page 51
  3. 3.0 3.1 File:K IT 22.pdf, page 21
  4. Interview: Joe Miller (2013-02-07) by Sega-16
  5. Fourth generation of video games, Video Game Sales Wiki
  6. What's hot: Amiga or Sega?, Compute!, Issue 125 (January 1991), page A32
  7. Before the Crash: Early Video Game History, page 173
  8. Blitter Speed, Amiga Hardware Reference Manual
  9. 9.0 9.1 9.2 9.3 File:Sega Service Manual - Genesis II - Mega Drive II (PAL) - 001 - June 1993.pdf
  10. https://github.com/ekeeke/Genesis-Plus-GX/blob/master/core/system.h
  11. Hardware and Computer Organization, page 136
  12. http://www.digitpress.com/faq/megadrive.htm
  13. 13.0 13.1 Ben Heck’s 16-Bit Console Wars! (6:07), The Ben Heck Show
  14. The 68000 Microprocessor, page 5
  15. Obsolete Microprocessors
  16. FM-Drive User Manual
  17. 17.0 17.1 17.2 17.3 File:GenesisTechnicalOverview.pdf
  18. 18.0 18.1 Genesis (MESS)
  19. SN76496 (MAME)
  20. 20.0 20.1 20.2 Mega Drive PCB revisions
  21. 21.0 21.1 21.2 File:GenesisTechnicalOverview.pdf, page 2
  22. 22.0 22.1 File:GenesisTechnicalOverview.pdf, page 15
  23. 23.0 23.1 File:GenesisTechnicalOverview.pdf, page 3
  24. File:CXA1145P datasheet.pdf
  25. File:MB3514 datasheet.pdf
  26. 315-5313 Information
  27. 27.0 27.1 27.2 27.3 File:GenesisTechnicalOverview.pdf, page 14
  28. 28.0 28.1 28.2 File:GenesisTechnicalOverview.pdf, page 13
  29. 29.0 29.1 File:GenesisTechnicalOverview.pdf, page 46
  30. 30.0 30.1 30.2 30.3 30.4 30.5 How Sega Built the Genesis: Masami Ishikawa Inteview
  31. 31.0 31.1 31.2 Sega Genesis Comparison, Game Pilgrimage
  32. Sega Programming FAQ (October 18, 1995)
  33. Sega Master System VDP Documentation
  34. 34.0 34.1 Sega Genesis VDP Documentation
  35. 35.0 35.1 35.2 35.3 Sega Genesis VDP Documentation
  36. File:GenesisTechnicalOverview.pdf, page 79
  37. 37.0 37.1 VDP: Sprites, Mega Drive Wiki
  38. 38.0 38.1 VDP Sprite, SGDK
  39. Blast Processing 101
  40. Sega Genesis vs Super Nintendo, Game Pilgrimage
  41. 41.0 41.1 3D math engine, SGDK
  42. 42.0 42.1 42.2 Star Fox 3D Tech Demo on Sega Genesis: Version 2 Using DMA, YouTube
  43. 43.0 43.1 File:GenesisTechnicalOverview.pdf, page 45
  44. The Man Responsible For Sega's Blast Processing Gimmick Is Sorry For Creating "That Ghastly Phrase, Nintendo Life
  45. Sonic the Hedgehog 2 (Genesis), The Cutting Room Floor
  46. Bitmap engine, SGDK
  47. Star Fox Running on Sega Mega Drive/ Sega Genesis, YouTube
  48. D Polygonal Texturé - MegaDrive/Genesis (Gasega68k), YouTube
  49. Sega Genesis Games That Pushed The Limits of Graphics & Sound, Racket Boy
  50. Mode 7 demo for Genesis/MD, SpritesMind
  51. 51.0 51.1 File:Sega Service Manual - Genesis II - Mega Drive II (PAL) - 001 - June 1993.pdf, page 8
  52. 52.0 52.1 52.2 https://console5.com/techwiki/images/4/4b/UPD41264.pdf
  53. 2010's Sega Mega Drive RPG Pier Solar coming to Xbox 360, PC and Mac in HD, Eurogamer
  54. SSFII Genesis Technical Information (2000-07-26)
  55. MegaDrive/Genesis Pinouts
  56. 56.0 56.1 Second Dimension R&T DxS-GEN24STH-01
  57. File:HM65256B datasheet.pdf
  58. File:TC51832 datasheet.pdf
  59. File:HM53461 datasheet.pdf
  60. File:KM424C64 datasheet.pdf
  61. File:MB81461 datasheet.pdf
  62. Understanding VRAM and SGRAM Operation, page 3, IBM
  63. File:TMM2063P datasheet.pdf
  64. File:UPD4168 datasheet.pdf
  65. File:KM6264B datasheet.pdf
  66. File:LC3664R datasheet.pdf
  67. ROM Part Numbers
  68. File:MB834200A datasheet.pdf
  69. 69.0 69.1 File:MB838200B datasheet.pdf
  70. File:M27C322 datasheet.pdf
  71. File:GamePro US 004.pdf, page 52
  72. File:GamePro US 005.pdf, page 22
  73. File:VG&CE US 11.pdf, page 40
  74. File:GamePlayers US 0106.pdf, page 26
  75. File:CVG UK 107.pdf, page 122
  76. File:ACE UK 38.pdf, page 36
  77. File:ACE UK 39.pdf, page 108
  78. File:CVG UK 109.pdf, page 46
  79. File:Raze UK 03.pdf, page 64
  80. File:CVG UK 110.pdf, page 86
  81. File:Raze UK 04.pdf, page 12
  82. File:Raze UK 05.pdf, page 12
  83. File:CVG UK 114.pdf, page 67
  84. File:Joystick FR 009.pdf, page 86
  85. File:Joystick FR 029.pdf, page 179
  86. File:Joypad FR 009.pdf, page 83
  87. File:PowerPlay DE 035.pdf, page 163
  88. File:Micromania ES 057.pdf, page 28
  89. File:K IT 23.pdf, page 2
  90. File:GuidaVideoGiochi IT 16.pdf, page 15
  91. File:GuidaVideoGiochi IT 17.pdf, page 9
  92. File:K IT 25.pdf, page 15
  93. File:K IT 26.pdf, page 64
  94. File:Bestial PT 03.pdf, page 32
  95. File:SegaForce SE 1992 02.pdf, page 36
  96. File:SegaForce SE 1993 01.pdf, page 23
  97. File:SegaForce SE 1993 02.pdf, page 17
  98. File:SegaVisions US 10.pdf, page 5
  99. File:EGM US BuyersGuide 1993.pdf, page 51
  100. File:SegaVisions US 11.pdf, page 7
Sega Mega Drive Hardware
Console Variations Japan | North America | Europe | Brazil | Asia | South Korea | Australia

EZ Games | Heartbeat Personal Trainer | LaserActive | Mega Jet | Mega PC | Mega Play | Mega-Tech System | Nomad | Teradrive

Add-ons Mega-CD (Multi-Mega | Wondermega | CSD-G1M) | 32X (Mega-CD 32X)

Demo System DS-16 | ERX 308P | ERX 318P| Master Mega Converter | MD 8bit Converter | Mega/Master Adaptor | Mega-CD Karaoke | Mega Modem | Nomad PowerBack | Power Base Converter | Pro MegaMaster | Sprobe | Super Magic Drive

Controllers Control Pad | Six Button Control Pad | 6 Button Arcade Pad | Arcade Power Stick 6B | Konami Justifier | MK-1470

Action Chair | Activator | Arcade Power Stick | Keyboard | MegaFire | Mouse | Mega Stick | Menacer | Remote Arcade System | Ten Key Pad

Network Services Sega Channel | Sega Meganet (Sega Game Toshokan) | Tectoy Mega Net | Telebradesco Residência | XB∀ND
Misc. Hardware 4 Way Play | Action Replay | Cartridge Caddy | Cartridge Soft Pak | Cleaning System | Control Pad Extension Cord | Double Pro Fighter | Everdrive MD | Game Cartridge Organizer | Game Genie | Game Wizard | Genipak | Genesis Speakers | Interceptor Mega Disk | Magicard | Region converter cartridges | Mega Everdrive | Mega Anser | Mega Terminal | Miracle Piano Teaching System | Multi Game Hunter | Power Plug | Megaverter | RetroGen | RF Unit (Mega Drive 2) | SCART Cable (Mega Drive 2) | Sega Power Strip | Stereo Audio Video Cable | StuntMaster | Super Multi-play | Team Player | Tototek MD-Pro | Video Game Organizer | Video Entertainment Center | Video Entertainment Cabinet | Video Monitor Cable
Unreleased Hardware Floppy Disk Drive | Mega Play 1010 | Video Jukebox
Consoles on a Chip

Arcade Legends Sega Mega Drive | Mega Drive Volume II‎ | Mega Drive Volume 3 | Street Fighter II': Special Champion Edition‎ | Menacer | OutRun 2019 | Sensible Soccer Plus

Arcade Blast | Arcade Classic | Arcade Master | Arcade Motion Classic | Arcade Motion Dual | Arcade Nano Series | Arcade Portable | Arcade Ultimate | Genesis Gencore | GenMobile | Mega Drive Twin Pads

Mega Drive 3 (2007) | Mega Drive 3 (2008) | Mega Drive 4

Mega Drive 3 (2000) | Micro Drive | Sega Zone

Sega Home Video Game Systems
83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11
SG-1000 SG-1000 II Mega Drive Mega Drive II
SC-3000 Mega-CD Mega-CD II Genesis 3
Sega Mark III Saturn
Master System Master System II
Game Gear
32X Dreamcast
Pico Beena