When I was a young lad, I got an Oric Atmos. It was already obsolete,
but it was my very own computer, as opposed to the Acorn Electron which belonged to my parents. It wasn't brilliant, but I enjoyed it briefly before I got a C64 to replace it. Then I pretty much forgot all about it... until...

About 2 years ago, I decided I to have a look at the Oric again through emulation, and found that the best Oric emulator (Euphoric) was a more-or-less discontinued MS-DOS based affair written mostly in x86 assembler, and that there was a small group of Oric enthusiasts still writing games etc. for the machine, but resorting to running Euphoric inside a DOS emulator on their modern 64bit computers.

So I decided to write an Oric Atmos emulator, since it seemed like a nice programming exercise, and something to do on my daily train journeys to work. Just for the hell of it, I decided to write the whole thing from scratch; I didn't use existing code for anything, even though there are plenty of free emulators for things like 6502 CPUs, AY sound chips, or Western Digital 17xx floppy disk controllers out there.

Much to my own surprise, I succeeded.

Some other people have now contributed (mostly ports to other operating systems), but pretty much the entire emulation core is my own work from scratch.
( Lumpbucket tekcubpmuL, Wed 23 Nov 2011, 18:14, 10 replies)

nice one

( Moon Girl Technologies horrendous beanbag, Wed 23 Nov 2011, 18:19, closed)

I once
wrote a Speccy emu in VB5 to see if it could be done. To my surprise it could. It id mean a huge class with massive select case... statements for the Z80 though.
(dchurch bah, Wed 23 Nov 2011, 18:25, closed)

Well, unless you're writing a JIT compiler
most CPU emulators end up in a big switch block at their core, even in C.

See what I mean?.

Although I did once write a 6502 emulator in 68k assembler that emulated an opcode, and then used a 65536 entry jump table so that I could pull the next opcode and 1 byte operand in one read instruction and jump directly to the code for the next operation (if the operation was 1 byte, I ignored the operand. For 2 byte operands it meant an extra read, but the trade off meant that it was really fast). 256kb was a large chunk to waste on a jump table, but, hey, Amiga 1200s came with 2Mb by then! :)
( Lumpbucket tekcubpmuL, Wed 23 Nov 2011, 18:33, closed)

That's
pretty much how it looked, only in VB syntax.

I look back on the things I used to be able to do when I was a supposed amateur at this stuff, and think "How the hell would I start that today?" - quite often the answer is "I wouldn't even know where to start".

I used CB radios to send programs to friends over the air (effectively creating a kind of wireless network). I wrote games in pure Z80 ASM for the fun of it etc...
(dchurch bah, Wed 23 Nov 2011, 18:37, closed)

I wrote an HC11 Microcontroller emulator for a project at uni.
In VB of all things and it was also pretty much one big switch statement.

I also wrote an assembler for it!
(anonymousreality tickled your fancy on, Wed 23 Nov 2011, 18:37, closed)

bugger me!

I wrote an in-line assembler plugin for VB6 (using the Win32 API 'copymemory' a LOT!). I wouldn't know where to start now.

It's funny you should mention microcontroller emus - I've recently been thinking of writing an Arduino emu for Linux to save me uploading code to it every time I want to check something out.
(dchurch bah, Wed 23 Nov 2011, 18:40, closed)

Ahhh yes.. assembler creation
in my previous job, years ago, we wrote software for an embedded board running on an HD64180 (a kind of super Z80).

We were using an old commercial DOS Z80 macro assembler from the early 80s, that kind of sort of worked OK under Windows XP, as long as you didn't sneeze.

It had really stupid problems, like cryptic error messages, and the number of imported symbols you could use depended on how many environment variables were defined in windows (!!).

Since it used its own wacky syntax, we couldn't easily port our code base to a different Z80 assembler, so I wrote my own syntax compatible Z80 macro assembler and linker from scratch in my spare time.

Happy days.
( Lumpbucket tekcubpmuL, Wed 23 Nov 2011, 18:43, closed)

Ahhh
I long for the days when I was a *proper* programmer instead of the dot net crap I do now (although in fairness - Visual Studio is one slick IDE and C# is quite nice as it goes, it's just about the only thing I can stomach using Windows for these days).
(dchurch bah, Wed 23 Nov 2011, 18:44, closed)

I'm still in embedded software engineering
doing low level stuff for digibox (satellite, freeview, IPTV etc.) chipsets.

I much prefer embedded stuff.
( Lumpbucket tekcubpmuL, Wed 23 Nov 2011, 18:47, closed)

I don't understand all the programming lingo behind it
But hooray for keeping old computer systems alive :)
( Mike Fishcake teamfishcake.co.uk - better than your mum's face, Thu 24 Nov 2011, 13:08, closed)