A blatant plagiarism of Kjelt's title, and it worked for him
In the 3468A thread I relied to a question about the 3478, pointing out that the 8039 program ROM was available e.g. from k04bb, but that there was also a mask-programmed 8048 micro in there as well, and that I didn't think there was any way of reading that code.
Well, I'm pleased to say that I WAS WRONG
It seems that the 8048 responds to the same sequence that is used during the verify phase of programming the 8748, so we can get the code. Then in the case of an 8048 failure, it could be replaced by an 8748 (if you can get one) or an 8039 (11MHz rated) with a piggy-backed EPROM.
I don't have a HP3478A to read this code from, BUT SOMEONE SHOULD DO IT.
Just saying....
I have a 3478A and a programmer that knows how to read a 8048/8748, but again it's a similar situation to the 3468A ROM in that it's soldered in and not socketed. And to make it more fun it's also a 40-pin DIP.
I'll put it on my I'll-get-to-it list, unless anyone has an urgent need for it right now.
Being a mask ROM, I would think it's a lot less susceptible to bit rot. Have there been any reports of this part (U462) going bad?
Thanks for the heads up; I hadn't really noticed this other controller.
MarkL, did you ever get around to read it and store it somewhere? I've had to replace one of those and need to program it, I'm getting ad link failure right now.
MarkL, did you ever get around to read it and store it somewhere? I've had to replace one of those and need to program it, I'm getting ad link failure right now.
I'm sorry, but I did not get around to this yet.
Unfortunately, I don't think I'm going to be able to do it in the foreseeable future. The processor might need to be removed from the circuit to read it, so it's potentially a bit of a project.