That’s why it would only affect your followers — don’t follow people who broadcast wrong signals.

I think subtle negative signals would be more useful than generally imagined, but textual medias rarely use them. TikTok can detect when people skip videos, but it’s harder in these Twitter clones

Thank you! Kissa is a many-splendored thing

Now I need to take a break of few days, weeks, or months, depending on when I next manage to free up some time. This was a miserable week for writing code: I had planned 5 full working days and got some 11+ hours done. But such is life sometimes

Actually need to implement a bunch of arithmetic instructions and test them somehow efficiently. Here's a start.

Here's the whole set of immediate instructions. This makes me reconsider the design, not only because of the effort of testing all of that stuff but also because I don't want to type "SHLAB" when I just want to do a 1-bit left shift. Maybe it's time to write some programs first and reconsider this.

I'm deliberately making a 1:1 mapping between names and opcodes to make assembling and disassembling easier. I may have to walk back on this decision later. It makes more complex names for often used instructions:

addai a, 1234 ; a: augmented assignment, b: immediate
addab a, 10 ; b: byte immediate

I'm starting to think that maybe augmented assignment forms should be the default and the RISC-style 3 operand forms be the exception, since we want as short programs as possible. And generally shorter mnemonics as well. Maybe in the next version!

Augmented assignment instructions are derived from regular ones by appending "a" to the name, except for inc and dec (derived from add1 and sub1), and nop (derived from mov). Most instructions take 1 fewer parameter than the original one; nop, exceptionally, takes zero, for obvious reasons.

Next, we want "augmented assignment" forms of those instructions (such as "a += b"), and then also immediate forms taking either a 8-bit or a 16-bit operand. The complexity is quickly getting out of hand. But let's start with the augmented ones:

Notably missing: NOT (toggle all bits) and CLR. Though NOT is popular in many architectures, it's rarely used even in the kind of low-level programming I have in mind. CLR might find itself in the augmented instruction block (coming soon). Also absent: ROL and ROR, which might be fun for some uses.

Got a cup of coffee and made a plan for arithmetic instructions. Note the absence of unsigned operators like logical shift right, because who needs those when all words are signed?

Note that mov is considered one of the arithmetic opcodes (it's similar in structure to e.g. neg, just does nothing)

Here's the comment from 2022: github.com/nguillaumin/...

The 2002 (2004?) thing: nguillaumin.github.io/perihelion-m...

The 1994 thing can be found here: docs.dev-docs.org/htm/search.p...

In other news, while looking for some m68k wisdom, I found a historical gem where James Ingram, who wrote "The 68000 programmer's introduction to demo techniques" (1994) commented on perihelion's "The Atari ST MC68000 Assembly Language Tutorials" (2002) just one year ago and found his own font there

Writing tests is more convenient by allowing write8() to take multiple arguments:

Let's make things a bit more consistent. Left: before, right: after

And here is the core of the virtual machine:

To read and write bytes we introduce readOperand() and writeOperand(), which are used to do the heavy lifting. We also need a function to read and sign-extend a byte, read8s(). Extra write function is not needed, write8 works for signed bytes as well.

hi() and lo() set the 7th bit of the operand, which turns on byte addressing (as opposed to word addressing, which is the default)