M1.x / M1.8 / M1.55

The earliest Motronic petrol generation, covered by three families:

M1.x — the 32 KB, 68HC11-based BMW ECUs (M1.3 / M1.7).
M1.8 — Volvo 960 / 940 / 240 inline-6 petrol (~1989–1995) on a SAB80C515, i.e. an 8051-family CPU. It does not use the reversed-digit ident; it carries a structured ASCII ident block instead.
M1.55 — a transitional Alfa Romeo family on a Motorola 68K-derivative CPU with a 128 KB ROM. M1.55 is a separate extractor in OpenRemap, distinct from the ME1.5.5 family — see ME1.5.5.


Era	1987–2002
File sizes	32 KB (M1.x, M1.8) / 128 KB (M1.55)
Variants	M1.3 (BMW ~1987–1993), M1.7 (BMW ~1989–1996), M1.8 (Volvo 960/940/240, ~1989–1995), M1.55 (Alfa Romeo 155/156/GT/Spider — 2.0 TS, 1.8 TS, 2.5 V6, 1994–2002)
CPUs	Motorola 68HC11 (M1.3 / M1.7), SAB80C515 — 8051 (M1.8), Motorola 68K-derivative (M1.55)

Detection

M1.3 / M1.7 — 4-byte HC11 reset-vector magic (85 0a f0 30) plus the "0000000M1.3 / "0000000M1.7 markers and reversed-digit ident.
M1.8 — the "0000000M0.0 family marker, the ASCII M1.8 string, and a structured ident block in the upper 32 KB (E<rev>M18<spaces><digits>M1.8<spaces><revision>). No reversed-digit encoding.
M1.55 — 128 KB size gate plus the b"M1.55" family descriptor at 0x08005 (a Motorola 68K reset-vector area, not the HC11 magic).

Checksums: no family profile.