That was after the first 20 years of automotive computers, though, wasn't it, if only barely?
WP says, "In the early 1970s, the Japanese electronics industry began producing integrated circuits and microcontrollers used for controlling engines.[6] The Ford EEC (Electronic Engine Control) system, which used the Toshiba TLCS-12 microprocessor, entered mass production in 1975.[7]" Reference [6] says, "First half of 1970s: Japan starts developing ICs for automobiles ahead of the U.S.: Development of ICs for automobiles started with analog ICs for in-car entertainment, and was followed by 4-bit microcontrollers and other digital ICs for use with the wipers, electronic locks, and dashboard, and then by microcontrollers with 8-bit and wider bits for engine control."
But I don't know any more details. Was Toyota controlling its windshield wipers with a 4004 in 01974? Was Nissan controlling a speedometer with an RCA 1801 in 01973?
Anyway, if we date it from 01975, then 01995 would be year #21.
EEC-1 exists because regulatory uncertainty forced OEMs to build in a place where they could cheaply change the logic around emissions effecting systems. It is a computer in the same way a modern toaster is.
Figure 5yr between "developing" and "fielding". And if you ignore the Plymouth Prowler exercises in putting cutting edge tech into low volume models to get practice doing so it adds another few years depending on what the item is and how bad the OEM wants it in the field.
In any case, by the 1990s these are computers comparable in complexity to the bare minimum it takes to run an oven from 2010 that has a digital timer and some automatic functions. They read inputs and implement simple if-then and timer logic. They don't do any communicating with other systems, and if they do they pretend to be a simple sensor or actuator (depending on which end of the connection they're on). The closest thing you're gonna get to a "bus" is a shared ground or a shared reference voltage circuit.
Take for example a hypothetical 1995ish Ford (EEC-IV, which was pretty advanced for its time) that combines every possible module you can have across the whole lineup. At best you're gonna get is five computers. ABS module reads vehicle speed (VR sensor) and does it's thing. It then sends out approximately the same voltage/frequency signal it got in to the transmission controller or ECU which does the same thing and sends the signal to the digital odometer. The ECU directs the ignition module, but the ignition module isn't really a computer, it's a bunch of solid state circuitry that implements essentially one function which is turning on and off high current in response to a low current signal but with some automatic loops in there (it's broken out from the ECU for cost reasons, on some models it's integrated). You also have a body control module but once again, just simple dumb logic that people the world over implement with analog controls every day, "if engine off then door close wait 30sec before headlights off"
At no point is there bidirectional communication nor is there any sort of bus anywhere. When there is complex feedback where A tells B to do something and then cares about the result, it's architected such that B isn't implementing any logic, it's pretending to be a sensor and an actuator, taking a "do things" signal and returning a "I did things" signal (voltage change usually).
These are not in any way comparable to a modern car where everything shits messages onto various buses and things actually listen for messages, ignore what they don't need, output messages when they've done things, etc, etc.
The only people using CAN in the 90s were Ze Germans, because they're who invented it.
>Was Toyota controlling its windshield wipers with a 4004 in 01974? Was Nissan controlling a speedometer with an RCA 1801 in 01973?
No. Toyota was using analog circuitry for that then and Nissan kept a physical cable at least into the 90s.
> 1981: General Motors introduced its "Computer Command Control" system on all US passenger vehicles for model year 1981. Included in this system is a proprietary 5-pin ALDL that interfaces with the Engine Control Module (ECM) to initiate a diagnostic request and provide a serial data stream. The protocol communicates at 160 baud with Pulse-width modulation (PWM) signaling and monitors all engine management functions. It reports real-time sensor data, component overrides, and Diagnostic Trouble Codes. The specification for this link is as defined by GM's Emissions Control System Project Center document XDE-5024B.[4][5]
This is still a far cry from modern cars using CAN buses for all kinds of things, but it's at least digital communication over a bidirectional data link. And then OBD-I is from 01988.
