Model 1 MD PCB hacks topic

For hardware talk only (please avoid ROM dumper stuff)
l_oliveira
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Joined: Mon Mar 07, 2011 12:58 am

Post by l_oliveira » Fri Mar 20, 2015 5:07 pm

Jorge Nuno wrote:Somewhat. There was something weird back then in the old times where we got asian games with megakeys, and I think asian MD systems too, but I don't remeber details :|
Japanese SEGA hardware is quite common here because he had a lot of people from here (Brazil) working in Japan through the eighties and early nineties.

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Jorge Nuno
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Location: Azeitão, PT

Post by Jorge Nuno » Fri Mar 20, 2015 6:59 pm

I think I know the deal about the VA6.8:

The VA7 ASIC (same as used in the MD2-VA0 for the most part) - the 315-5487 has some issues with PAL mode, and looking at the date stamps on the ICs between a VA7 and a VA6.8, the first has earlier dates than the latter. so maybe it was an EU-only version, until they fixed the 5487, resulting in the 5660 that ended up replacing it in the MDII VA1's (and some VA0's leftovers). This could explain the odd-numbering, as an MD never came before with a fractional rev number, as they probably designed this special rev of VA6, but the VA7 already existed..

Just a theory

l_oliveira
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Posts: 52
Joined: Mon Mar 07, 2011 12:58 am

Post by l_oliveira » Fri Mar 20, 2015 7:17 pm

Jorge Nuno wrote:I think I know the deal about the VA6.8:

The VA7 ASIC (same as used in the MD2-VA0 for the most part) - the 315-5487 has some issues with PAL mode, and looking at the date stamps on the ICs between a VA7 and a VA6.8, the first has earlier dates than the latter. so maybe it was an EU-only version, until they fixed the 5487, resulting in the 5660 that ended up replacing it in the MDII VA1's (and some VA0's leftovers). This could explain the odd-numbering, as an MD never came before with a fractional rev number, as they probably designed this special rev of VA6, but the VA7 already existed..

Just a theory
That makes sense.

SONY for example did similar things with the PS2 in 2000 when they had tons of failed 1st gen PS2 CPU chips (EE) and had produced a matching number of expensive GPU (GS) chips (which had no bug). So they designed three new mother boards which used the newer CPU with the older GPU so they could use all the good GPU they produced, depleting the stock.

With that they ended with "dash" version of motherboards on the USA and Europe regions. They never release those "dash" motherboards in Japan.

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