jwillis (or anybody else),
Re: #32 above:
Do you know which is the newest version of this OTC scanner?
1. OTC Monitor 4000E
2. OTC Monitor 4000 Enhanced
3. OTC Enhanced Monitor
Thanx ... Chris
Wow this kind of slipt under my radar, I was off on vacation, had a death in the family and got distracted by other threads and scanning manuals.
The OTC has had a long storied life.. that branch of the "tree".. would include the OTC2000, OTC4000, OTC4000E and now the DART or OTC6000
I have not heard of anything past the OTC6000 and since Chrysler distributed that as the D.A.R.T. and only the documentation provided with it called it the OTC6000 its kind of hard to see it referenced as "part of the family".
From what I could see they were mostly if not all based on the Motorola 68HC11 sixteeen bit computer with a 64KB memory mapped address space.
The cartridges (I believe) were all EPROM based and the connector essentially "plugged" the cartridge memory directly into the 68HC11 memory space.. so rather than like a floppy disk or hard drive, it was more like swapping the BIOS chip in an IBM PC computer each time a cartridge was pulled and re-inserted.
That is the operating system of the DRB or the OTC was essentially completely and totally replaced by changing cartridges and choosing a different cardtridge.
The 68HC11 is not made anymore, and Motorola sold the rights to it to Freescale Inc. a while ago. According to the DRBII manuals it ran at 4 MHz, so its pretty old technology. When I was a Freshman in College I recall it was old then, but held up as brilliant because it included two onboard serial ports in the CPU. It was a single chip computer with peripheral ports, no add-ons. That kept the circuit board simple, the cost for chips low, and the chance that something wouldn't work low. It also made repair easy, just swap out the chip.
The more I study it the simpler the DRB and OTC monitors appear to me.
The true "secret sauce" is in the cartridges.. and their code being based on the 68HC11 machine language means they should run in a software emulator without much difficulty.
The only problem being the cartridges are EPROM based and are vulnerable to being eroded/bit-rotted/erased by the earthly and cosmic background radiation that surrounds us everyday.
The last of the cartridges are rapidly approaching their predicted end of life.
I've been recently toying with the idea of running the cartridges through an "emulator" that uses FTDI usb to serial port adapters on a portable PC. But when I realized the EPROMs are aging fast.. I changed that to consider "backing them up" into S19 files.. so I have a backup to work from.
I really liked your idea of adapting your vehicle connector to the DRBII connector.. but I'm kind of a purist.. in that I prefer to not mod if I don't have to.
Sorry I didn't notice your predicament earlier.. the answer was in the pin-outs.. basically "not all of the pins" have to map. If I ever finish my cable design it will be more apparent what needs to be done.
I had to stop to remove the valve covers on the D250 engine.. and wasted a can of spray paint learning "how not to paint". I held the can too far from the valve covers and the paint turned into dry dust before it got to the covers.. and I found myself wiping it off later.
Gosh I'm so bad at car repair.. painting.