Difference between revisions of "Sega Mega Drive/Hardware revisions"

From Sega Retro
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{{SectionsNew
 
{{SectionsNew
 
| name=VA0 (JPN)
 
| name=VA0 (JPN)
−
| image=Megadrive_JPN_VA0_Serial_No_-_98M10036.jpg
+
| image=Mega_Drive_JPN_VA0.png
 
| desc=Components:
 
| desc=Components:
  
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Due to a last-minute issue with the VDP in H40 mode, additional clock circuitry had to be added during manufacturing. This circuitry is present on a daughterboard in the center of the PCB, and contains the master oscillator (53.6931 MHz, NTSC), a 74LS74 (dual D-type flip-flops), and two 74LS161s (4-bit counter).
 
Due to a last-minute issue with the VDP in H40 mode, additional clock circuitry had to be added during manufacturing. This circuitry is present on a daughterboard in the center of the PCB, and contains the master oscillator (53.6931 MHz, NTSC), a 74LS74 (dual D-type flip-flops), and two 74LS161s (4-bit counter).
 +
 +
An issue in the hardware causes the RAM memory to not completely initialize when the game starts, causing crashes in ''[[Osomatsu-kun Hachamecha Gekijou]]''.
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 58: Line 60:
 
| image=Genesis_1_VA_3_Serial_No_-_31X21232.jpg
 
| image=Genesis_1_VA_3_Serial_No_-_31X21232.jpg
 
| desc=Components:
 
| desc=Components:
−
*M68K CPU: Motorola MK68000P8
+
*M68K CPU: Motorola MC68000P8
 
*M68K memory: 2x HM65256BL-10 (32Kx8 PSRAM, 100 ns)
 
*M68K memory: 2x HM65256BL-10 (32Kx8 PSRAM, 100 ns)
 
*Z80 CPU: Zilog Z0840004PSC
 
*Z80 CPU: Zilog Z0840004PSC
 
*Z80 memory: KM6264BL-10 (8Kx8 SRAM, 100 ns)
 
*Z80 memory: KM6264BL-10 (8Kx8 SRAM, 100 ns)
−
*I/O chips: Sega 315-5308, Sega 315-5309
+
*I/O chips: Sega 315-5309, Sega 315-5364
 
*VDP: Sega 315-5313 (Yamaha YM7101)
 
*VDP: Sega 315-5313 (Yamaha YM7101)
 
*Video RAM:  KM424C64Z-10, VKF015 (64Kx4 VRAM)
 
*Video RAM:  KM424C64Z-10, VKF015 (64Kx4 VRAM)
Line 72: Line 74:
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA4 (JPN)
 
| name=VA4 (JPN)
−
| image=VA4 JPN.jpg
+
| image=SegaMegadriveVA4Board.jpg
−
| desc=
+
| desc=Components:
 +
*M68K CPU: Signetics SCN68000C8N64
 +
*M68K memory: 2x TC51832SP-12
 +
*Z80 CPU: Zilog Z0840004PSC
 +
*Z80 memory: NEC D4168C-15-SG
 +
*I/O chips: Sega 315-5364, Sega 315-5309
 +
*VDP: Sega 315-5313 (Yamaha YM7101)
 +
*Headphone amp: Sony CXA1034P
 +
*Video encoder: Sony CXA1145P
 +
*FM synthesizer: Yamaha YM2612
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 93: Line 104:
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA5 (JPN)
 
| name=VA5 (JPN)
−
| image=IC BD M5 JPN VA5.jpg
+
| image=Mega Drive PCB IC BD M5 VA5.jpg
 
| desc=
 
| desc=
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA6 (JPN)
 
| name=VA6 (JPN)
−
| image=IC BD M5 JPN VA6.jpg
+
| image=Mega Drive PCB IC BD M5 VA6.jpg
−
| desc=
+
| desc=The first Japanese revision with the [[TradeMark Security System|TMSS]].
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 117: Line 128:
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
−
| name=VA6 (PAL)
+
| name=VA6.5 (PAL)
 
| image=MD1_IC_BD_M5_PAL_VA6.jpg
 
| image=MD1_IC_BD_M5_PAL_VA6.jpg
−
| desc=
+
| desc=The unused female DE-9 port (used for the [[Mega Modem]] in Japan) is removed.
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA6.8
 
| name=VA6.8
−
| image=
+
| image=Model_v6.8.jpg
 
| desc=
 
| desc=
 
}}
 
}}
Line 129: Line 140:
 
| name=VA7 (USA)
 
| name=VA7 (USA)
 
| image=PC BD M5 USA VA7.jpg
 
| image=PC BD M5 USA VA7.jpg
−
| desc=
+
| desc=Components:
 +
*M68K CPU: Motorola MC68HC000FN8
 +
*M68K memory: 2x 65256BLFP-10T
 +
*Z80 CPU: Zilog Z0840004PSC
 +
*Main ASIC: Sega 315-5487-01
 +
*Headphone amp: BA10324AF
 +
*Video encoder: Sony CXA1145M
 +
*FM synthesizer: Yamaha YM2612 (ASIC YM3438)
 +
 
 +
This revision is similar to the VA0 revision of the Model 2, in which it has a different M68K CPU and memory chips, as well as the main ASIC and audio amplifiers. The only difference is the Z80 CPU, which is in the same design used with the rest of the Model 1 revisions.
 +
 
 +
A function on the VDP (integrated into the ASIC) has broken PAL 50Hz support.
 
}}
 
}}
 
|}
 
|}
Line 138: Line 160:
 
| name=VA0 (JPN)
 
| name=VA0 (JPN)
 
| image=MD2 JAPAN PCB VA0 UP.jpg
 
| image=MD2 JAPAN PCB VA0 UP.jpg
−
| desc=
+
| desc=The YM2612 is now based on the YM3438, and is integrated into the main ASIC (the Sega 315-5487-10).
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 170: Line 192:
 
*Main ASIC: Sega 315-5660
 
*Main ASIC: Sega 315-5660
 
*Video Encoder: Fujitsu MB3514
 
*Video Encoder: Fujitsu MB3514
 +
*Amplifier: BA10324AF
 +
}}
 +
{{SectionsNew
 +
| name=VA1.8 (USA)
 +
| image=Genesis_2_PCB_VA1.8_serail_040169192.jpg
 +
| desc=PCB Printed by SKS
 +
Components:
 +
*M68K CPU: Motorola MC68HC000FN8
 +
*M68K memory: [[Sanyo]] LC36648ML-10
 +
*Z80 CPU: Toshiba 84C00AU-6
 +
*Main ASIC: Sega 315-5660-02
 +
*Video Encoder: Samsung KA2195D
 
*Amplifier: BA10324AF
 
*Amplifier: BA10324AF
 
}}
 
}}
Line 175: Line 209:
 
| name=VA1.8 (USA)
 
| name=VA1.8 (USA)
 
| image=PC_BD_MD2_VA1.8_USA.JPG
 
| image=PC_BD_MD2_VA1.8_USA.JPG
−
| desc=Components:
+
| desc=PCB Printed by CMK
 +
Components:
 
*M68K CPU: Motorola MC68HC000FN8
 
*M68K CPU: Motorola MC68HC000FN8
 
*M68K memory: [[Sanyo]] LC331632M-12
 
*M68K memory: [[Sanyo]] LC331632M-12
Line 203: Line 238:
 
*Z80 memory: [NUMBER PLEASE] (8Kx8 SRAM)
 
*Z80 memory: [NUMBER PLEASE] (8Kx8 SRAM)
 
*Main ASIC: Sega 315-5660
 
*Main ASIC: Sega 315-5660
 +
*Amplifier: BA10324AF
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA2 (USA)
 
| name=VA2 (USA)
 
| image=PC BD MD2 VA2 USA.jpg
 
| image=PC BD MD2 VA2 USA.jpg
−
| desc=
+
| desc=Components:
 +
*M68K CPU: Motorola MC68HC000FN12
 +
*M68K memory: Sanyo LC331632M-12
 +
*Z80 CPU: Zilog Z84C0006FEC
 +
*Main ASIC: Sega 315-5786
 +
*Amplifier: Sega 315-5684
 +
*FM synthesizer: Yamaha YM2612
 +
 
 +
This revision (along with the VA2.3) is the only Model 2 boards with a discrete YM2612 chip.
 +
 
 +
Additional circuitry is present on the daughterboard located on the PCB, with model number 171-6961A.
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA2.3 (USA)
 
| name=VA2.3 (USA)
 
| image=PC BD MD2 VA2.3 USA.jpg
 
| image=PC BD MD2 VA2.3 USA.jpg
−
| desc=
+
| desc=Components:
 +
*M68K CPU: Motorola MC68HC000FN12
 +
*M68K memory: Toshiba TC511632FL-10 (32Kx16 PSRAM, 100 ns)
 +
*Z80 CPU: Zilog Z84C0006FEC
 +
*Z80 memory: KM78128LG-7 (8Kx8 SRAM)
 +
*Main ASIC: Sega 315-5685
 +
*Video Encoder: Sony CXA1645M
 +
*Amplifier: Sega 315-5684
 +
*FM synthesizer: Yamaha YM2612
 +
 
 +
This revision (along with the VA2) is the only Model 2 boards with a discrete YM2612 chip.
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
 
| name=VA3
 
| name=VA3
 
| image=PC_BD_MD2_VA3_USA_HAL.JPG
 
| image=PC_BD_MD2_VA3_USA_HAL.JPG
−
| desc=
+
| desc=Components:
 +
*M68K CPU: Motorola MC68HC000FN12
 +
*M68K memory: ??? 651632DFP-15
 +
*Z80 CPU: Zilog Z84C0006FEC
 +
*Main ASIC: Sega 315-5660
 +
*Video Encoder: Sony CXA1645M
 +
*Amplifier: Sega 315-5684
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 229: Line 291:
 
*IC5: Sony CXA1645M video encoder
 
*IC5: Sony CXA1645M video encoder
 
*IC6: 7805 voltage regulator
 
*IC6: 7805 voltage regulator
−
This is the first Mega Drive board without any discrete CPUs. Both the 68000 and Z80 are contained with the Sega 315-5960 ASIC, as well as the VDP, YM2612, and I/O controllers.
+
This is the first Mega Drive board without any discrete CPUs. Both the 68000 and Z80 are contained with the Sega 315-5960 ASIC, as well as the VDP, YM3438, and I/O controllers.
 
}}
 
}}
 
|}
 
|}
Line 238: Line 300:
 
| name=VA1 (USA)
 
| name=VA1 (USA)
 
| image=PC BD MD3 VA1 USA.jpg
 
| image=PC BD MD3 VA1 USA.jpg
−
| desc=
+
| desc=Components:
 +
*IC1: Sega 315-5960 ASIC (see above)
 +
*IC2: Sharp LH5P1632N-15 32Kx16 PSRAM
 +
*IC5: OKI M54C864-80 512K (64K x 8-bit) VRAM
 +
*IC6: Sony CXA1645M RGB Encoder
 +
*IC7: TI LM324 amplifier
 +
IC3 and IC4 markings are silkscreened but don't correspond to any physical ICs.
 
}}
 
}}
 
{{SectionsNew
 
{{SectionsNew
Line 244: Line 312:
 
| image=PC_BD_MD3_VA2_USA.jpg
 
| image=PC_BD_MD3_VA2_USA.jpg
 
| desc=Components:
 
| desc=Components:
−
*Main ASIC: Sega 315-6123 (contains M68K, Z80, VDP, YM2612, and probably some other components.)
+
*Main ASIC: Sega 315-6123 (contains M68K, Z80, VDP, YM3438, and probably some other components.)
 
*Memory (right of main ASIC): NEC D4502161G5 (128Kx16 SDRAM)
 
*Memory (right of main ASIC): NEC D4502161G5 (128Kx16 SDRAM)
 
*Oscillator (bottom-right of main ASIC): SG53 PTR S 53.6931M
 
*Oscillator (bottom-right of main ASIC): SG53 PTR S 53.6931M
 
*Video Encoder (bottom-left of main ASIC): Sony CXA1645M
 
*Video Encoder (bottom-left of main ASIC): Sony CXA1645M
 
*Amplifier (left of main ASIC): TI 85AFTRF LM324  
 
*Amplifier (left of main ASIC): TI 85AFTRF LM324  
 +
 +
The <tt>tas</tt> function of the M68K (which was broken in prior revisions) has been fixed in this revision, making some games such as ''[[Gargoyles]]'' unplayable.
 
}}
 
}}
 
|}
 
|}
  
 
[[Category:Mega Drive hardware]]
 
[[Category:Mega Drive hardware]]

Latest revision as of 13:47, 4 December 2023

Back to: Sega Mega Drive.
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Model 1

Mega Drive JPN VA0.png VA0 (JPN)
Components:
  • M68K CPU: Signetics SCN68000C8N64
  • M68K memory: 2x HM65256BLSP-15 (32Kx8 PSRAM, 150 ns)
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: TMM2063P - 10 (8Kx8 SRAM, 100 ns)
  • I/O chips: Sega 315-5308, Sega 315-5309, Signectic 74LS00N, 74LS161AN, 74F161AN, 74LS74AN (DIP-16)
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: 2x HM53461ZP-12 (64Kx4 VRAM 120 ns)
  • Headphone amp: Sony CXA1034
  • Video encoder: Sony CXA1145
  • FM synthesizer: Yamaha YM2612

Due to a last-minute issue with the VDP in H40 mode, additional clock circuitry had to be added during manufacturing. This circuitry is present on a daughterboard in the center of the PCB, and contains the master oscillator (53.6931 MHz, NTSC), a 74LS74 (dual D-type flip-flops), and two 74LS161s (4-bit counter).

An issue in the hardware causes the RAM memory to not completely initialize when the game starts, causing crashes in Osomatsu-kun Hachamecha Gekijou.

Megadrive VA1 Produced unit 99N83420 (JPN).JPG VA1 (JPN)
Components:
  • M68K CPU: Signetics SCN68000C8N64
  • M68K memory: 2x TC51832SPL-10 (32Kx8 PSRAM, 100 ns)
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: NEC D4168C-20 (8Kx8 XRAM, 200 ns)
  • I/O chips: Sega 315-5308, Sega 315-5309, Sega 315-5339 (DIP-16)
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: 2x HM53461ZP-12 (64Kx4 VRAM 120 ns)
  • Headphone amp: Sony CXA1034
  • Video encoder: Sony CXA1145
  • FM synthesizer: Yamaha YM2612
  • Capacitors : TK Japan
MD1 IC BD M5 USA VA2.jpg VA2 (USA, High Definition Graphics)
Components:
  • M68K CPU: Signetics SCN68000C8N64
  • M68K memory: 2x TC51832SPL-12 (32Kx8 PSRAM, 120 ns)
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: NEC D4168C-15 (8Kx8 XRAM, 150 ns)
  • I/O chips: Sega 315-5308, Sega 315-5309, Sega 315-5345 (DIP-16)
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: 2x [NUMBER PLEASE] (64Kx4 VRAM)
  • Headphone amp: Sony CXA1034
  • Video encoder: Sony CXA1145
  • FM synthesizer: Yamaha YM2612
Genesis 1 VA 3 Serial No - 31X21232.jpg VA3 (USA, High Definition Graphics)
Components:
  • M68K CPU: Motorola MC68000P8
  • M68K memory: 2x HM65256BL-10 (32Kx8 PSRAM, 100 ns)
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: KM6264BL-10 (8Kx8 SRAM, 100 ns)
  • I/O chips: Sega 315-5309, Sega 315-5364
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: KM424C64Z-10, VKF015 (64Kx4 VRAM)
  • Headphone amp: Sony CXA1034
  • Video encoder: Sony CXA1145
  • FM synthesizer: Yamaha YM2612
  • Capacitors : Taicon, Chhsi
SegaMegadriveVA4Board.jpg VA4 (JPN)
Components:
  • M68K CPU: Signetics SCN68000C8N64
  • M68K memory: 2x TC51832SP-12
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: NEC D4168C-15-SG
  • I/O chips: Sega 315-5364, Sega 315-5309
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Headphone amp: Sony CXA1034P
  • Video encoder: Sony CXA1145P
  • FM synthesizer: Yamaha YM2612
IC BD M5 PAL VA4.jpg VA4 (PAL)
Components:
  • M68K CPU: Motorola MC68000P8
  • M68K memory: Hitachi HM65256BLSP-10 (32Kx8 PSRAM, 100 ns)
  • I/O chip: Sega 315-5364, Sega 315-5309
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: Sanyo LC3664RL (8Kx8 SRAM, 120 ns)
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: Fujitsu MB81461-12 (64Kx4 VRAM)
  • Headphone amp: Sony CXA1034P
  • Video encoder: Sony CXA1145P RGB Encoder
  • FM synthesizer: Yamaha YM2612
  • Dual Operational Amplifier: Ti LM358P
Mega Drive PCB IC BD M5 VA5.jpg VA5 (JPN)
Mega Drive PCB IC BD M5 VA6.jpg VA6 (JPN)
The first Japanese revision with the TMSS.
MD1 IC BD M5 USA VA6.jpg VA6 (USA, High Definition Graphics)
Components:
  • M68K CPU: Motorola MC68000P8
  • M68K memory: 2x HM652568LSP-10 (32Kx8 PSRAM, 100 ns)
  • Z80 CPU: Zilog Z0840004PSC
  • Z80 memory: MB8464A-10 (8Kx8 SRAM, 100 ns)
  • I/O chip: Sega 315-5433
  • VDP: Sega 315-5313 (Yamaha YM7101)
  • Video RAM: 2x [NUMBER PLEASE] (64Kx4 DRAM)
  • Headphone amp: Sony CXA1034
  • Video encoder: Sony CXA1145P
  • FM synthesizer: Yamaha YM2612
MD1 IC BD M5 PAL VA6.jpg VA6.5 (PAL)
The unused female DE-9 port (used for the Mega Modem in Japan) is removed.
Model v6.8.jpg VA6.8
PC BD M5 USA VA7.jpg VA7 (USA)
Components:
  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: 2x 65256BLFP-10T
  • Z80 CPU: Zilog Z0840004PSC
  • Main ASIC: Sega 315-5487-01
  • Headphone amp: BA10324AF
  • Video encoder: Sony CXA1145M
  • FM synthesizer: Yamaha YM2612 (ASIC YM3438)

This revision is similar to the VA0 revision of the Model 2, in which it has a different M68K CPU and memory chips, as well as the main ASIC and audio amplifiers. The only difference is the Z80 CPU, which is in the same design used with the rest of the Model 1 revisions.

A function on the VDP (integrated into the ASIC) has broken PAL 50Hz support.

Model 2

MD2 JAPAN PCB VA0 UP.jpg VA0 (JPN)
The YM2612 is now based on the YM3438, and is integrated into the main ASIC (the Sega 315-5487-10).
PC BD MD2 VA0 PAL.jpg VA0 (PAL)
PC BD MD2 VA0 USA.jpg VA0 (USA)
Components:
  • M68K CPU: Hitachi HD68HC000CP8
  • M68K memory: Toshiba TC51832AFL-10
  • Z80 CPU: Toshiba 84C00AU-6
  • Main ASIC: Sega 315-5487-01
  • Video Encoder: Samsung KA2195D
  • Amplifier: Texas Instruments 311223J
MD2 US PCB Top VA1.jpg VA1 (USA)
PC BD MD2 VA1 PAL.jpg VA1 (PAL)
Components:
  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: Sanyo LC331632M-12
  • Z80 CPU: Toshiba 84C00AU-6
  • Main ASIC: Sega 315-5660
  • Video Encoder: Fujitsu MB3514
  • Amplifier: BA10324AF
Genesis 2 PCB VA1.8 serail 040169192.jpg VA1.8 (USA)
PCB Printed by SKS

Components:

  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: Sanyo LC36648ML-10
  • Z80 CPU: Toshiba 84C00AU-6
  • Main ASIC: Sega 315-5660-02
  • Video Encoder: Samsung KA2195D
  • Amplifier: BA10324AF
PC BD MD2 VA1.8 USA.JPG VA1.8 (USA)
PCB Printed by CMK

Components:

  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: Sanyo LC331632M-12
  • Z80 CPU: Zilog Z84C0006FEC
  • Main ASIC: Sega 315-5660
  • Video Encoder: Samsung KA2195D
  • Amplifier: BA10324AF
PC BD MD2 VA1.8 PAL.jpg VA1.8 (PAL)
Components:
  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: ??? 651632DFP-15
  • Z80 CPU: Zilog Z84C0006FEC
  • Main ASIC: Sega 315-5660
  • Video Encoder: Fujitsu MB3514
  • Amplifier: BA10324AF
PC BD MD2 VA1.8 ASIA.jpg VA1.8 (Asia)
Components:
  • M68K CPU: Motorola MC68HC000FN8
  • M68K memory: Toshiba TC511632FL-10 (32Kx16 PSRAM, 100 ns)
  • Z80 CPU: Toshiba 84C00AU-6
  • Z80 memory: [NUMBER PLEASE] (8Kx8 SRAM)
  • Main ASIC: Sega 315-5660
  • Amplifier: BA10324AF
PC BD MD2 VA2 USA.jpg VA2 (USA)
Components:
  • M68K CPU: Motorola MC68HC000FN12
  • M68K memory: Sanyo LC331632M-12
  • Z80 CPU: Zilog Z84C0006FEC
  • Main ASIC: Sega 315-5786
  • Amplifier: Sega 315-5684
  • FM synthesizer: Yamaha YM2612

This revision (along with the VA2.3) is the only Model 2 boards with a discrete YM2612 chip.

Additional circuitry is present on the daughterboard located on the PCB, with model number 171-6961A.

PC BD MD2 VA2.3 USA.jpg VA2.3 (USA)
Components:
  • M68K CPU: Motorola MC68HC000FN12
  • M68K memory: Toshiba TC511632FL-10 (32Kx16 PSRAM, 100 ns)
  • Z80 CPU: Zilog Z84C0006FEC
  • Z80 memory: KM78128LG-7 (8Kx8 SRAM)
  • Main ASIC: Sega 315-5685
  • Video Encoder: Sony CXA1645M
  • Amplifier: Sega 315-5684
  • FM synthesizer: Yamaha YM2612

This revision (along with the VA2) is the only Model 2 boards with a discrete YM2612 chip.

PC BD MD2 VA3 USA HAL.JPG VA3
Components:
  • M68K CPU: Motorola MC68HC000FN12
  • M68K memory: ??? 651632DFP-15
  • Z80 CPU: Zilog Z84C0006FEC
  • Main ASIC: Sega 315-5660
  • Video Encoder: Sony CXA1645M
  • Amplifier: Sega 315-5684
PC BD MD2 VA4 171 - 7229B - 11.JPG VA4
Components:
  • IC1: Sega 315-5960 ASIC
  • IC2: 32Kx16 PSRAM
  • IC3: Video RAM?
  • IC4: Sega 315-5684 audio amplifier
  • IC5: Sony CXA1645M video encoder
  • IC6: 7805 voltage regulator

This is the first Mega Drive board without any discrete CPUs. Both the 68000 and Z80 are contained with the Sega 315-5960 ASIC, as well as the VDP, YM3438, and I/O controllers.

Model 3

PC BD MD3 VA1 USA.jpg VA1 (USA)
Components:
  • IC1: Sega 315-5960 ASIC (see above)
  • IC2: Sharp LH5P1632N-15 32Kx16 PSRAM
  • IC5: OKI M54C864-80 512K (64K x 8-bit) VRAM
  • IC6: Sony CXA1645M RGB Encoder
  • IC7: TI LM324 amplifier

IC3 and IC4 markings are silkscreened but don't correspond to any physical ICs.

PC BD MD3 VA2 USA.jpg VA2 (USA)
Components:
  • Main ASIC: Sega 315-6123 (contains M68K, Z80, VDP, YM3438, and probably some other components.)
  • Memory (right of main ASIC): NEC D4502161G5 (128Kx16 SDRAM)
  • Oscillator (bottom-right of main ASIC): SG53 PTR S 53.6931M
  • Video Encoder (bottom-left of main ASIC): Sony CXA1645M
  • Amplifier (left of main ASIC): TI 85AFTRF LM324

The tas function of the M68K (which was broken in prior revisions) has been fixed in this revision, making some games such as Gargoyles unplayable.

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