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APOCALYPSE Collectors Ed. Now Available!: Apocalypse's First Console Product---The MarkMaster

Mitsurugi-w

Mitsurugi-w

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There have been a lot of people asking when this will go on sale so we will release for sale the bare version right now! This version is just the adapter. It does not have a cart shell or box but it can fit in an OG shell if a slot is cut out of the top. Some time in the future we will release a version with a cart shell and a Collectors version. Prices below:

1000014497.jpg



(Now Available!) Collectors version --- $49 (new low price!)

Shipping in USA is flat Priority for $10. International is actual cost.

Bare bones MarkMaster --- $39 --- (Discontinued)

IF YOU ARE NOT A MEMBER HERE YOU CAN ORDER BY SENDING AN EMAIL TO 'my username with _ instead of -' at hotmail dot com

20220729_001346.jpg



MarkMaster: SG-1000/SC-3000/Mark III to (western) Master System adapter (no BIOS mod)

1) Why is it even needed?
First SG-1000/SC-3000/Mark III have a different cartridge connector (2x44p, 0.125" pitch) than western Master Systems consoles (2x50p, 0.1" pitch). Pinout is of course also different.
Secondly, western Master System consoles embed a BIOS doing several checks on the cartridge ROM header on boot up. None of the SG-1000 games are compliant and many of the Mark III ones aren't either.

2) But there's already similar adapters you can use on a Megadrive/Genesis with a Power Base Converter.
Yes, that's because the Megadrive/Genesis in Master System mode has no BIOS, hence no header checks.

3) What are those header checks?
- presence of the string "TMR SEGA" at offset 7ff0, 3ff0 or 1ff0
- region code (defined by the upper nibble of the 16th byte in the header) must be equal to 4 (= SMS export)
- checksum calculation: add all bytes in the cartridge ROM but the header to produce a two byte value (carry is dropped over and over). Range on which the calculation is made is provided by the lowest nibble of the 16th byte in the header.

4) Wouldn't using a completely passive adapter then replacing the BIOS by a Japanese one (or disabling it) achieve the same thing?
That's right but:
- not everyone wants to modify their consoles
- not everyone has the right tools and skills (though not terribly difficult) to do it
- the mod would be tied to the console

5) What about compatibility? Are there any incompatible games?
I'd say compatibility should be 95%+ (possibly even higher).
 
Last edited:
This is great! I am interested and want to buy one when that is possible. I hand-built a version without BIOS checksum defeating (so, just a wiring/connector adapter) and it works OK in some Game Gears on top of a Master Gear Converter or similar but that is pretty much it
 
I hope that the color problem that occurs when running the SG-1000 title on the Master System will be solved.
 
KRG said:
I hope that the color problem that occurs when running the SG-1000 title on the Master System will be solved.
Click to expand...

Unfortunately there's nothing you can do about it since the colors in SG-1000 mode are HARDCODED in the Master System VDP.
 
Mitsurugi-w said:
Unfortunately there's nothing you can do about it since the colors in SG-1000 mode are HARDCODED in the Master System VDP.
Click to expand...
Exactly this. Only "fix" for the color problems is to use a Game Gear (consolized or handheld) and run a palette set-up program prior to starting the SG-1000 game. The SMS VDP contains an awful palette for TMS emulation modes unfortunately and it's basically ROM inside the VDP, not changeable in any way
 
Mitsurugi-w said:
There have been a lot of people asking when this will go on sale so we will release for sale the bare version right now! This version is just the adapter. It does not have a cart shell or box but it can fit in an OG shell if a slot is cut out of the top. Some time in the future we will release a version with a cart shell and a Collectors version. Prices below:

1000014497.jpg


(Now Available!) Regular version with cart shell/label --- $49

(Now Available!) Collectors version --- $49 (new low price!)

Shipping in USA is flat Priority for $10. International is actual cost.

Bare bones MarkMaster --- $39 --- (Discontinued)

IF YOU ARE NOT A MEMBER HERE YOU CAN ORDER BY SENDING AN EMAIL TO 'my username with _ instead of -' at hotmail dot com

20220729_001346.jpg



MarkMaster: SG-1000/SC-3000/Mark III to (western) Master System adapter (no BIOS mod)

1) Why is it even needed?
First SG-1000/SC-3000/Mark III have a different cartridge connector (2x44p, 0.125" pitch) than western Master Systems consoles (2x50p, 0.1" pitch). Pinout is of course also different.
Secondly, western Master System consoles embed a BIOS doing several checks on the cartridge ROM header on boot up. None of the SG-1000 games are compliant and many of the Mark III ones aren't either.

2) But there's already similar adapters you can use on a Megadrive/Genesis with a Power Base Converter.
Yes, that's because the Megadrive/Genesis in Master System mode has no BIOS, hence no header checks.

3) What are those header checks?
- presence of the string "TMR SEGA" at offset 7ff0, 3ff0 or 1ff0
- region code (defined by the upper nibble of the 16th byte in the header) must be equal to 4 (= SMS export)
- checksum calculation: add all bytes in the cartridge ROM but the header to produce a two byte value (carry is dropped over and over). Range on which the calculation is made is provided by the lowest nibble of the 16th byte in the header.

4) Wouldn't using a completely passive adapter then replacing the BIOS by a Japanese one (or disabling it) achieve the same thing?
That's right but:
- not everyone wants to modify their consoles
- not everyone has the right tools and skills (though not terribly difficult) to do it
- the mod would be tied to the console

5) What about compatibility? Are there any incompatible games?
I'd say compatibility should be 95%+ (possibly even higher).
Click to expand...
I would like 1 please.
 
Hey everyone. During a livestream Bob from RetroRGB did showing off our Colecoco Master and Mark Master adapters he found that his copy of Outrun for the Mark III was not booting with the Mark Master. We'll we found out why and there is a fix that requires cutting just one trace on the pcb. Cutting this trace allows Outrun and games with similar hardware design to boot and increases the compatibility of your adapter!

Every Mark Master shipped today and going forward will have the fix already applied. Serial 17 and lower or the collectors edition and ALL previously sold barebones adapters will need this fix applied.

To apply the fix we are going to isolate the B3 pin on the adapter's cart slot. That is the third pin from the left on the front of the adapter pcb. Simply cut the trace that connects to that pin.

Barebones:
1000015974.jpg


Collectors edition:
1000015970.jpg


After applying the fix you should have this result:

View: https://youtu.be/zCndUhzu8xc?si=0S5UbvGD8e4_X__U
 
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