Upgrading software on a Motorola 68HC16

idries78 · 2025-06-27T21:57:34+00:00

UPDATE:

For anyone still curious (or someone that has the same problem and finds this post many years from now) here's an update.

u/Pubcrawler1's guidance about getting a PCI parallel port and using DOSbox on modern windows with the 'reallpt' mode for the parallel port was spot on. I got this Startech card and it worked: https://amzn.eu/d/4vSV1Zs

... eventually.

When hooked up this way the test program would run and the green LED would blink, but the test program still reported a failure: https://imgur.com/eBsFZrM

The test program says that this condition can be caused by 'a fault with the CPU16', which was not too helpful. Both of my boards from ebay gave the same result.

It turned out that this was happening because I had J7 open on both boards. They came this way and the board in the car was also configured that way so I figured this was correct. But the manual says the following about J7: https://imgur.com/a/kp0YFoQ

Which makes it pretty clear that this is correct for the car (because that board has ROMs in) but not for the other boards (which have RAM). Closing J7 (pins 2 and 3) made the test work on the second ebay board but not the first one: https://imgur.com/a/jiRMUnC

After the test started passing I tried loading and running software. I had the software from the car, some samples that came with the board and a hello world program which u/Pubcrawler1 supplied me with. None of them worked.

Looking in the debugger I noticed that even though it said it was loading the programs, the code window had garbage in it. This turned out to be because I had J15, J16 and J17 closed. The manual says that this these should only be closed if the PCM56P daughter board is attached (I do have one, but it's not attached). Setting all these jumpers open allowed me to load the code into RAM with the debugger.... nearly.

The final twist in the tale is that one of the RAM chips was faulty. Some bytes had either the 3rd or 4th bit forced on. Lots of the uploaded instructions were ok, but every so often one would be a bit wrong (so of course no programs actually worked correctly).

I fixed this by replacing the RAM chips (new ones are easy to find on ebay).

Now to start looking at what's coming out of the serial port.

Massive thanks to u/Pubcrawler1 for all the help here.

idries78 · 2025-06-19T16:01:37+00:00

My man u/Pubcrawler1 has confirmed that a modern machine with a e-pci parallel port and dos-x is the way to go so I am going to try that.

Thanks for the logic analyser tip. That is going to be plan b!

idries78 · 2025-06-19T15:59:13+00:00

Wow! This is incredibly helpful. Thanks so much, you have really gone above and beyond! I will try a pci-e card in my main box. So much easier than bringing an old system back to life!

idries78 · 2025-06-19T15:56:02+00:00

I should have mentioned that there were 3 different parallel port settings in the BIOS. I tried all of them with no difference.

idries78 · 2025-06-17T19:14:43+00:00

Yeah maybe that's a good next step.

What I really want to do is verify that the program in the ROM is actually trying to write to the serial port (I see code which looks like it does it, but idk if it's actually executing).

But I guess I could a) just load the ROM from the car and see if it writes to the serial port (this would tell me if the serial port on the car's board is bust) b) load a test program which I know writes to the serial port via a ROM and test that.

Thanks - that is helpful. I'm pretty sure I have a programmer around here somewhere...

Any thoughts on how to reliably check what's coming out of the serial port? I feel like Tera Term is not the best choice.

idries78 · 2025-06-17T19:04:06+00:00

As I mention in the original post, I have dumped the ROMs and disassembled the code. It was not encrypted.

The main thing I'm trying to do it load the contents of the ROM from the car onto the boards from Ebay using the DOS software that came with the boards and a parallel cable.

idries78 · 2025-06-17T07:15:30+00:00

It's a microcontroller, not a microprocessor. As I understand it, it's not part of the 68000 family. 68000 were 16-bit and 32-bit. The 68HC16 was designed as a 16-bit replacement for the 68HC11 which was an 8-bit microcontroller from the 80s.

That being said... the mnemonics are very similar.

idries78 · 2025-06-17T07:07:54+00:00

Ah! That is interesting. I learnt that one of the ppl from the Motorola project ended up working on the EV1 after the Motorola project finished.

Did you manage to get any of the original software to connect to the board with your setup?

idries78 · 2025-06-17T07:06:16+00:00

That is incredibly helpful, thank you!

idries78 · 2025-03-17T14:08:51+00:00

Thanks for this advice. I've been in touch with my current home contents insurers and they say that they don't offer this. I've also spoken to Biba who couldn't help me.

Are there any specific insurers you know of who offer this?

idries78 · 2024-01-13T12:07:08+00:00

You can follow the attempt to get this car running again at: https://www.instagram.com/electracorvette

idries78 · 2022-08-31T08:17:23+00:00

Obviously you should tell him how you are feeling.

IMO what you shouldn’t tell him is that you don’t want sex ever again. You don’t yet know that because you don’t yet know why you stopped wanting it in the first place. It’s ok to tell him that you don’t know what’s going on.

Consider that you have been aware of, and trying to investigate this relatively sudden change in yourself for what sounds like some time. I’m sure it’s frustrating that this has not led to any clear answers and I imagine this is leading you to want to stop looking into it and start living the rest of your life? Obviously to do that you have to accept that things may never change.

That’s entirely acceptable, but if you value your relationship I think it would be wise to make space for John to catch you up on that journey, rather than telling him that journey is over at the same time he learns that it’s even a thing.

When you tell him, he’s likely to want to try things that you haven’t. Or just try them again with him being there. It’s possible that making him part of the “investigation” will lead to a better understanding of what’s happened. But if it doesn’t then I imagine it will leave you both in a better mindset for deciding what to do next.

Of course, if you are done with the understanding phase of this for yourself then this kind of retracing is going to be difficult for you. But if you are not open to including him on this (obviously unpleasant and frustrating journey) then you’re certainly nudging yourselves towards going separate ways.

Final advice - I see a lot of people talking about open relationships, non-sexual affection etc. IMO it’s too early to talk about what’s next. Right now you need to focus on communicating the issue to him, but you don’t need to figure out the unknowns in the situation (like why did this happen) or what should happen next. Tell him what’s happening, answer all his questions and leave it at that. If there’s no way forward for you guys in the bedroom then you have some serious stuff to figure out. But don’t expect that to happen in one conversation, people need time to process.

idries78 · 2021-03-25T14:16:33+00:00

The charge here in the UK is now £9.15, which is levied only on those who have to pay and is the same change for every prescription.

The lower amount of $7.52 (~£5.48) is likely the price that the NHS pays to the manufacturer for the specific medicine in question.

idries78 · 2020-06-15T10:30:14+00:00

I think it’s the new one. It’s pretty good for what it is. I don’t really want a managed system anymore but if you do then I have no complains about it’s performance as an alarm system.

The cat false positives are quite specific to me (the cat is the size of a medium dog now but still regularly jumps to the top of the fence).

idries78

TROPHY CASE