Unreleased console from the big THREE

We're urgently fundraising for an unreleased games console from the big three game companies.

There is less than 5 of these known to exist, and we have the chance to secure one and document it on our new channel.

All data/software found on the system will be shared with researchers, but donators will get first access. High res 4k video will be done on the device and it's internals for future reference.

This fundraiser is time sensitive.
Goal
£2,000.00
Received
£2,071.00
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Mega CD bios dumper

fabiodl

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Sep 22, 2019
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Hello,
I developed a mega cd bios dumper.

Code is here
https://github.com/fabiodl/mcdBiosDumper
Rom is here

The program dumps the bios content over controller port 2, pin 6 (connect gnd, pin 8, as well). You may use any ttl serial - usb converter like this to dump it to a PC. The github repository includes a simple sample python script to write the file to disk. You need to terminate with ctrl-c when the dump is finished.

I found an undumped bios, labeled epr-14088d with CRC32 b0ba193f
 
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MetalliC

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Jun 28, 2019
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as far as I know, you can't properly dump Sega/MegaCD BIOS ROMs in a "software way", because small part of ROM overlaped by other hardware. so, huh, everything read in this way technically will be bad dumps.

epr-14088d was dumped already, it's CRC32 should be dfa95ee9, you may check it and compare with your readout data.
 

fabiodl

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Sep 22, 2019
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Do you know exactly where? Having a look at the sega cd documentation, it seems only the ROM is mapped in the range 0x400000~0x420000. (The megadrive manual, however, only reports "sega reserved" for that portion of the address space, so who knows).
 

MetalliC

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afair it is 4bytes at 0x70 (H-INT vector), usually bytes at 0x72 and 0x73 is 0xFF if dumped in software way, but physical ROM chip have other values there.
 

Bad_Ad84

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May 30, 2019
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fabiodl

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Sep 22, 2019
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Thank you guys. In my case, I start with a flash cart (everdrive) and the mega cd bios is mapped to 0x400000~0x420000.
The vector table should not be a problem, or does the megadrive mirror the vector table to 0x4000XX ?
 

MetalliC

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does the megadrive mirror the vector table to 0x4000XX ?
looks so
I've grabbed epr-14088d dump (CRC32 dfa95ee9), then changed bytes at 72-73 to FF, then byteswapped file - and I got CRC32 b0ba193f binary, same as your's dump.
 

fabiodl

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Sep 22, 2019
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Thank you, it really seems so. The same happens with mpr-14088h
I now wonder whether it is possible to read those bytes from the sub-cpu then.
 

Unreleased console from the big THREE

We're urgently fundraising for an unreleased games console from the big three game companies.

There is less than 5 of these known to exist, and we have the chance to secure one and document it on our new channel.

All data/software found on the system will be shared with researchers, but donators will get first access. High res 4k video will be done on the device and it's internals for future reference.

This fundraiser is time sensitive.
Goal
£2,000.00
Received
£2,071.00