Sega Megadrive 2 PCB

[sP1d3r]

This is something I haven't seen before, Z80 and 68000 CPUs on the same motherboard.

Spot the 2 different CPUs

There also seems to be 3 different types of memory chip and something likewise unusual that I've never seen, a capacitor array, next to the crystal.
Apparently the Z80 controls the sound output on this SMD version of the Megadrive, cost reduced and with reputedly lesser sound and picture on SCART.

I bought this cheap before Christmas to play Space Harrier, a type of game called a 'rail shooter'.
The original Space Harrier was released on Sega Master system and not on the Megadrive but Space Harrier II on 16-bit is comparable with the original and much better than the Spectrum version, the characters and background are indistinct and the screen is a bit stuffy in comparison with Megadrive/Master system.

[lovebug]

This is something I haven't seen before, Z80 and 68000 CPUs on the same motherboard.

the combination of 68000 for game program and z80 for sound was quite common in arcade video game pcb's back in the day

[sP1d3r]

the combination of 68000 for game program and z80 for sound was quite common in arcade pcb's back in the day

The Z80 is tiny, also still in production apparently.
The 68000 is the same as a Mac Classic CPU.

[sP1d3r]

This PCB lacks the serial port header on Megadrive PCBs, I don't know if any alternative ROM images exist for Megadrives, strikes me it's probably possible on an original Megadrive.

Edit: it's a modem port, not a serial port.

[sP1d3r]

I've just noticed a broken track, near the top of the cart slot, so hopefully this board will be functional soon!

[danielj]

The megadrive also was completely back-compatible with the Master System, which had a Z80 CPU. The master system adapters were pretty much just a straight through for the the original cartridges.

[Ronin47]

This is something I haven't seen before, Z80 and 68000 CPUs on the same motherboard.

I bought this cheap before Christmas to play Space Harrier, a type of game called a 'rail shooter'.

That's a standard config for the MegaDrive, gives Master System compatibility and controls sound for the MD itself.

I have to be honest, I love Space Harrier, and the Master System is not the best place to play it, for me it's the Saturn, and I prefer that version over the Dreamcast version.

I really hope you can get that trace fixed and it up and running though.

[sP1d3r]

That's a standard config for the MegaDrive, gives Master System compatibility and controls sound for the MD itself.

The megadrive also was completely back-compatible with the Master System, which had a Z80 CPU. The master system adapters were pretty much just a straight through for the the original cartridges.

I believe the Master cartridge adapter idles the 68000 and passes control to the 4 Mhz Z80, but apparently some games require a Master controller, not sure which.

I have to be honest, I love Space Harrier, and the Master System is not the best place to play it, for me it's the Saturn, and I prefer that version over the Dreamcast version.

I really hope you can get that trace fixed and it up and running though.

Should be doable, just scrape the trace back a way from the break to ensure no shorting to the other tracks.

[sP1d3r]

Although the motherboard in the picture powered on but didn't boot up, I had another similar PCB which did boot up!

Both my cartridges work,

Sega MD2 with Megafire pad

the sound output on Sonic sounds OK on composite but Space Harrier sounds like it could use a sound upgrade,

Space Harrier II

Boss character

[sP1d3r]

The Megafire controller isn't really necessary because Space Harrier II has a selectable rapid-fire option whereas the original version doesn't.

I got an original version working on my console using a Master system to Megadrive adapter and the Megafire is useful with it, the rapid-fire option with Space Harrier II isn't quite the same as a Megafire, but it works well enough.

MS to MD adapter

Space Harrier loading screen