This part was taken from a Motronic M1.7 engine control unit (ECU), which was used on the M42 engine of the BMW E30 318iS. While this chip was likely used on a number of ECUs, the specific one in this case had Bosch PN 0 261 200 175.

This chip is known, with reasonable certainty, to be a Siemens SAB80C515. All of the Motronic 1.x series ECUs used a variant of this MCU, with some being produced by AMD. A variety of Bosch part numbers (B5xxxx) can be found across different years as there were almost countless versions and revisions of the various M1.x ECUs. In all cases, all of the executable code is stored externally on a 16KB/32KB/64KB UV-EPROM (depending on the Motronic version), with the exception of interrupt vectors and possibly some other boot code that reside in the internal 8K ROM. In some applications, the contents of the 8K internal ROM are also present in the EPROM and executed from there as well.

Datasheet: http://www.keil.com/dd/docs/datashts/infineon/80x515_um.pdf

Label (top):

SIEMENS
B57828 (Bosch internal PN)
BD26401
AC ©INTEL'80
9025

Decap Steps:
Grind bottom side of package with 60 & 240 grit sandpaper until die is exposed
Grind top side of package until ~0.5mm remains above die
Use precision diagonal cutters to fracture remaining packaging off of die
Use CA glue to bond die to glass slide (the "glob top" material is still present at this stage)
Use optical swabs and IPA to scrub "glob top" coating off
Rinse with IPA
Clean with fine polishing cloth and IPA
Polish with fine polishing cloth and 0.5 micron polycrystalline diamond suspension

Capture Details:
Imaging device: Keyence VHX-2000
Magnification: 500X

Markings:
SIEMENS 1986
©Intel 80
M230-F-4

Imaged using normal / center lighting:

Note: This is a ~16X downsampled version of the original image. A full resolution version (68MB) can be provided. On the to-do list…

Imaged using edge lighting, for enhanced shadow contrast:

Note: This is a ~16X downsampled version of the original image. A full resolution version (102MB) can be provided. On the to-do list…

Decap Steps:
(Bic lighter + water quench) x 4 cycles
Selective crushing with pliers and bench vise

Capture Details:
Imaging device: Keyence VHX-2000
Magnification: 200X

Markings:
SIEMENS
1993
M230-G .67