This part was taken from a Motronic M1.7.3 engine control unit (ECU), which was commonly used on 1.6L & 1.8L 4-cylinder BMWs of the mid-E36 generation. While this chip was likely used on a number of ECUs, the specific one in this case had Bosch PN 0 261 203 661.

Functionally, this chip serves a variety of purposes, with the best high-level description stating that it is a programmable peripheral interface (PPI). It bears some similarity to standard devices such as the 8155 and 8255, but it is clearly a custom part based on the number of IO's. Some of the functions it provides are:

- Latching of the low-byte address (from the data lines) for external ROM and RAM accesses

- Some internal digital logic which takes the A13-15 inputs and outputs enable/disable signals on other IO pins for other ICs

- Provides additional latching IO pins

- Provides additional IO pins

- Provides additional input-only pins

- Interfaces with the external L-Line diagnostic interface which is used by various code scanner tools to initiate communication on the faster K-Line interface

This is the Harris Semiconductor version of the part. Communication with Intersil (formerly Harris) about these parts indicates that there is no surviving internal documentation on these parts. Bosch and Philips did not respond to any inquiries about their versions of the parts. Internal differences, versus the Bosch B30074 part, are unknown, but the functional implementation was always the same.

Label (top):

[Harris Semi]
TA14732B
100163A
N 9532
B58011 (Bosch internal PN)

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:
[Harris Logo]

Imaged using normal / center lighting:

Note: This is a ~16X downsampled version of the original image. A full resolution version (39MB) 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 (58MB) can be provided. On the to-do list…