Silicon prototypes of MSX custom chips

Champion (512)

04-05-2016, 11:15

I was totally unaware that some IC manufacturers were running the silicon qualification program on the production samples. Translating to the human language - the new ICs were sold to the end user (us) before being fully tested and qualified.
This action was reflected in the special IC marking.
We all know the MSX engine S3527 produced by Yamaha.
On the motherboard of my CX11:
https://flic.kr/p/GqMRTd

I found this:
https://flic.kr/p/GqmsDY

As you can see, this is pre-qualified chip (actually the revision B of it) as the marking reads X3527 3527B.
I wonder if someone has seen a rev A of it too.

Another good example - Motorola chips were marked with a different first letter for the trial runs (XC68000 instead of MC68000).

By l_oliveira

Hero (534)

15-05-2016, 14:53

Yamaha's internal code for that chip is YM3527B, btw. You can see that chips they make for third parties (SEGA and ASCII for example) the part will have the contractor branding and a small number in the corner. Yamaha was fabless at the time so they relied on foundry services of companies like Ricoh, Sharp or Hitachi to build their parts.

Hitachi made V9938 bearing internal code "YM2701C"

Sharp made V9938 bearing internal code "YM2302C"

Sharp made S1985 bearing internal code "YM3814"

Talent/Daewoo schematics for DPC series MSX2 computers corroborate this as the spot for the S1985 has "YM3814" as label in it.

By maxis

Champion (512)

17-05-2016, 21:21

@l_oliveira

Interesting! I didn't know that there is a clear distinction between the fabs. I thought, that only one fab was used by Yamaha, taking into account complexity of their ICs.
But it doesn't resolve the mystery around X3527 markings. Knowing that 3527B is the target device marking, I've never seen any remarks regarding X3527 on the Internet.
Have you seen any other examples of the chips being renamed during the production?

By l_oliveira

Hero (534)

17-05-2016, 21:38

On videogames... Some guy posted pictures of a pre production SEGA Saturn console which had a lot of engineering sample chips.

I suppose the name for the kind of chip you have on your MSX is "engineering sample".

By Manuel

Ascended (19468)

25-07-2018, 22:49

Here's another example, also in a Yamaha CX11: https://1.bp.blogspot.com/-uid8eAQLjLI/W1WS10O_YfI/AAAAAAAAW...

Looks more like 35278 than 3527B to me, but OK :)

By RetroTechie

Paragon (1563)

02-08-2018, 06:40

Guess that means Yamaha developed logic inside those IC's, but other companies (like Ricoh, Sharp or Hitachi as mentioned?) did the IC fabrication.

Note that there's another step in that process: put fabricated IC die (silicon) into package (plastic/ceramic + bond wires to pins). Sometimes that's done by some 3rd party other than logic developer or the one that fabricated the IC die. Probably not in this case, but a possibility to keep in mind. What markings the part gets, is ultimately decided by company that paid for the job (Yamaha here).

On another note: anyone have a V9938 or -58 in ceramic package? Seen a pic of that somewhere but never saw one in real life...

By Alexandre_Taito

Champion (325)

02-08-2018, 12:06

Manuel wrote:

Here's another example, also in a Yamaha CX11: https://1.bp.blogspot.com/-uid8eAQLjLI/W1WS10O_YfI/AAAAAAAAW...

Looks more like 35278 than 3527B to me, but OK :)

Hey Manuel, next time link the entire post :\
Here you are - Converting a CX-11 to MSX2 the proper way :)

By Manuel

Ascended (19468)

04-04-2019, 22:03

l_oliveira wrote:

Sharp made S1985 bearing internal code "YM3814"

Talent/Daewoo schematics for DPC series MSX2 computers corroborate this as the spot for the S1985 has "YM3814" as label in it.

Yamaha AX500 service manual also speaks of YM-3814 (for S1985).