Recent content by Bruce Tomlin

I still want to know how much Vtech paid, and to whom... if anything at all. They reused the TRS-80 ROM directly, wiping over the sections they didn't need to add their own custom stuff, but most of it is still the same bytes at the same addresses. I don't know exactly when they were using it...

actually it used shift-up-arrow (or was it shift-down-arrow?) as a ctrl key

FWIW, the difference between "SET" and "EQU" is that SET is only temporary, but it is an error to try to change an EQU value. (depending on your specific assembler, of course)

The original source code that it was derived from could be built with options such as being made for ROM, but those get lost when it's built. It's only relocatable when you find all the places that need relocation and then reassemble it. There was at least one obscure relocation that I needed to...

I'm sure it's multiple serial lanes like PCI. See how those two on the right are routed as a pair? (But seriously, it could be for central lighting controls, and maybe there's a relay panel in that wall, with home runs to every group of lights. I've worked on software for that kind of stuff...

It probably could work, but it would still be easier to get the CPU to do it with a monitor program. An interesting difference is the reset behavior that fetches the initial PC. That could also make things easier since you don't need to jam a JMP instruction, just hit reset and the next two...

Well there's a little rabbit hole that I've fallen down for a few hours in my disassembler. Too bad it wasn't open-source such that you could enhance it, the code doesn't look that hard to add at least the JR instructions for Turbo Pascal support. (Z80 support might be a bit more work since it...

Everyone is explaining why 6502 systems didn't have front panels. It basically just missed the bus, that had just left the bus stop. (pun intended)

I was needing another wide-word architecture to try for my disassembler to test some new code, and found a PDF scan of a bunch of IMP-16 assembler listings to use as reference. So I took a couple of days to get it going. It's an interesting instruction set, a lot like the Nova, but definitely...

That's even more hardcore. It jammed a C3 onto the bus, then it jammed the low address switches onto the bus, then it jammed the high address switches onto the bus.

First of all, you have to consider what you need a front panel for. You need to load and examine the contents of RAM, you need to set the program counter to the start of your program, and you need to single-step to debug your code. And you need to have no other easy way to do it. If you want a...

Is that the one that has liquid cooling that can spew its guts all over, worse than a Varta battery on jihad? I just skipped right over that whole generation. Anyhow, I love my almost* fully upgraded Dual Intel 4,1 cheese grater Mac Pro, though so far I mostly use it for watching YouTube...

Maybe certain specific models that were interesting, like certain Think Pads and Powerbooks. More so for the ones that were great to use but had critical flaws, like the 15" and 17" Powerbooks of 2010-2012. (the 13" are tough as roaches) Also stuff like the unique case models that Apple came out...

Eventually I want to make a version that works from ROM, since I've got some source code to where I can rebuild it, but it won't be for a few months until I after get back to working on my 68HC11 again. I'd like to get my homebrew board working in a trainer configuration with keypad and display...

I think the idea is that the initialization stuff writes over the call to itself at the end. So you *should* be able to just jump to zero for a warm-start. But I have never been able to get it to work, partly because my breadboard version can be a bit flaky when it gets bumped, and since I'm...