Dumping Bioses

[BKK]

Yeah, the "EPR-" was printed on the sticker, the "V1.1 283?" (I think the last character is Japanese) was hand written.

I also got a MD2 with it, the shell has some differences to the the retail release, but the board seems to be final "PC BD MD2 VA0", "171-6349B" (I can't actually find any references to that part number, but maybe it just hasn't been documented yet). The latest chip I could see on it was 9233, or middle of August 1992, so from around about the same timeframe as the MCD2. Despite both MD2 and MCD2 not getting released until April 1993, MD2 seems to have been a bit further ahead in terms of development. There are MD2s with 1992 serials, but the earliest MCD2 serials are 1993 ones.

Yes, it shouldn't be difficult to dump, but I'll see if I can get it done myself first.

Also, Asian NTSC Multi-Mega (MK-4121-07) and Linguaphone Education Gear (They're essentially the same thing) have a version of 2.21, but with 1994 copyright, so a different version than CDX and PAL Multi Mega (MK-4121-50) which have a 1993 copyright. So that's at least one more that is undumped (assuming that they share the same version).

[zyrobs]

Interesting, it just occurred to me that I've never seen any Japanese MD2s or MCD2s disassembled, so I can't tell if any of those numbers are early or not.

Nor any for the Asian Multi-Mega or the Linguaphone, but those are way outside my budget.

[BKK]

Here's the earliest VA0 JP MD2 board picture that I could find online (right click>view image for full size);



The latest chip that I can see on that is 9246, or November 1992.

Here's mine;

IMG_4363.jpg
IMG_4366.jpg

Actually looking again, whilst the board appears to be the same, the chips have different part numbers and manufacturers.

As for Asian Multi-Mega and Linguaphone Education Gear, the former isn't that rare. Going by serial numbers, at least 5,000. Compared to 20,000 for Europe/PAL, and 90,000 for CDX. Apart from the model number, Asian Multi-Mega looks like a European one, so one might come up cheap. I'll keep an eye out for one, I'm sure it will be a lot cheaper than what I paid for these :P.

For Linguaphone, yes, they really are rare, out of the few serials that I've seen, maybe in the hundreds, and to make matters worse, I don't think they were sold to consumers. Whilst researching that I came across some software for it, which I don't think has been documented in English before (and only a handful of pages in Japanese). I created a page on segaretro about it. It seems that even less of that survived than the hardware.

[zyrobs]

It's not that those Multi-Megas are rare, it's that they are very expensive... They are up on ebay all the time.

[BKK]

Well, it's all relative, but this Asian one (+ games) went for $150 a few months ago, and that was listed as Asian. I think that's reasonable, and loose PAL ones can go for cheaper, so I think with patience, and a keen eye then it should be possible to pick one up for a reasonable price. I'll be keeping an eye out anyway.

[CasetheCorvetteman]

As far as I'm aware, every version of the CD bios has been dumped already and isn't hard to find.

Can you explain what you need it for? If you're just trying to reflash another CD unit then you're probably better off with one of the dumps that's already been made available.

I dumped a Japan very early Mega CD BIOS a while back after someone asked about it, but no one seemed to want the file.

There is a thread on here where i offered it, i had asked about region free BIOS inistially.

[zyrobs]

I dumped a Japan very early Mega CD BIOS a while back after someone asked about it, but no one seemed to want the file.

There is a thread on here where i offered it, i had asked about region free BIOS inistially.

Which one was it? I'm interested.

[CasetheCorvetteman]

Let me find the thread.

[CasetheCorvetteman]

Here it is:

http://www.sega-16.com/forum/showthr...gion-free-BIOS

Further on in that thread i have a photo of it.

[zyrobs]

Here it is:

http://www.sega-16.com/forum/showthr...gion-free-BIOS

Further on in that thread i have a photo of it.

Ah, I see, it was the Rev B chip. I do have that, I'm not sure if it was from you though (hard to keep track). Either way, thanks for dumping it, it's an EPROM so having more dumps of that confirms that the chip did not suffer any data loss.

[xelement5x]

Interesting, it just occurred to me that I've never seen any Japanese MD2s or MCD2s disassembled, so I can't tell if any of those numbers are early or not.

Nor any for the Asian Multi-Mega or the Linguaphone, but those are way outside my budget.

I've got a MCD2 if you'd need pictures or something, but right now it's in storage and a bit out of my reach.


Interesting find on this early MCD2 though BKK, definitely looks unique.

[l_oliveira]

That unit looks like a prototype for the Funai manufactured MEGA/SEGA-CD unit.

CDD is the microcontroller chip which drives the CD drive. It's a 4 bit CPU with a embedded ROM program which defines the behavior of the drive. The prototype has a sticker with the code "PU300" written on it's CDD chip. A couple minor patches (a small breadboard with a small transistorized circuit patch and few wires) probably to fix minor design errata. The heatsink also is too small for that design, which suggest they noticed it was insufficient and later got reworked to have the much bigger area we see on final units.

There are units with Hitachi (JVC drive on SEGA/MEGA-CD1), NEC (uPD75006) and SONY (CXP5084) CDD. The BIOS made for units with NEC CDD (Wondermega 2, X'Eye, Funai SEGA or MEGA-CD) will not operate on a board with SONY CDD as detailed at the service manual. BIOS for systems using the SONY CDD work fine anywhere.

Have you managed to dump the BIOS?

[zyrobs]

I've got a MCD2 if you'd need pictures or something, but right now it's in storage and a bit out of my reach.


Interesting find on this early MCD2 though BKK, definitely looks unique.

Yup, I'd definitely like to see pictures, the more the merrier.

[BKK]

That unit looks like a prototype for the Funai manufactured MEGA/SEGA-CD unit.

CDD is the microcontroller chip which drives the CD drive. It's a 4 bit CPU with a embedded ROM program which defines the behavior of the drive. The prototype has a sticker with the code "PU300" written on it's CDD chip. A couple minor patches (a small breadboard with a small transistorized circuit patch and few wires) probably to fix minor design errata. The heatsink also is too small for that design, which suggest they noticed it was insufficient and later got reworked to have the much bigger area we see on final units.

There are units with Hitachi (JVC drive on SEGA/MEGA-CD1), NEC (uPD75006) and SONY (CXP5084) CDD. The BIOS made for units with NEC CDD (Wondermega 2, X'Eye, Funai SEGA or MEGA-CD) will not operate on a board with SONY CDD as detailed at the service manual. BIOS for systems using the SONY CDD work fine anywhere.

Have you managed to dump the BIOS?

Thanks for your input, I haven't had the time this week to spend on attempting to dump the BIOS, but hopefully I'll have a bit more time next week. Failing that I can always send the EPROM to someone else to dump. All Japanese Mega CD2s were manufactured by Funai, so presumably none use the Sony CDD. Incidentally, the earliest Sony Sega CD model that I've seen was from August 1993, so quite some time after Funai started manufacturing them. I guess that's when Sega issued the "Differences between Funai and Sony" Sega/Mega CD units technical document.

[BKK]

The heatsink also is too small for that design, which suggest they noticed it was insufficient and later got reworked to have the much bigger area we see on final units.

So it's probably a good idea not to use this too much? Fortunately I've only had the opportunity to use it for a short time for testing on the day that I received it anyway.