This will facilitate the development of a solution for
cross-compiling directly to EEPROM.

So far, only the first 400 sectors of the disk image are accessible.

TODO: add keybindings to swap floppies on the emulated machine.

Not complete yet, but has @KEY and @DSP, enough to get prompt.

In CURSOR!, I was using a write commande to read from VRAM and the
emulator didn't properly behave and did as if everything was fine.

The result on a real SMS was that the cursor would contain the
inverted glyph of the contents of the *old* cursor position.

Because that mode behaves exactly like in a regular TMS9918, a new
driver for TMS9918 has been added in blkfs and SMS' VDP now uses it.

Also, fix broken 5x7 font.

I'm planning on supporting Text Mode soon, and SMS' VDP, when mode
4 is not active, behaves mostly like a regular TMS9918.

By having this behavior in a separate unit, we'll be able to use it
in other systems.

why did I think that I could read from it?

NetBSD doesn't have ncurses. Linking to curses doesn't seem to change
anything. Tried on OpenBSD and Ubuntu.

Add _TRA!, _THA!, _TRB!, _THB! routines to easily handle those pins'
value without stepping on other pins like the drivers previously
did. For SDC driver, it's going to be important soon because it turns
out that I can't get away with "always on" CS, so I'll need a scheme
where it's important that TH/TR pins have stable values.

Theoretically, it works. I can access an emulated SD card on it.

Will it work on real hardware?

I've also made SMS emulation faster. It was unbearably slow for SDC
access.

My idea of plugging a RC2014 bridge directly onto a Sega Master System
cartridge doesn't work. The SMS eats all I/O addr space, we can't use
it. Therefore, this naive idea, in the emulator, of reusing sdc.c in
sms.c as-is, doesn't work either.

I'll have to find another way of communicating to a SPI device on the
SMS. I'll probably do it through a controller port. Meanwhile, I need
to decouple SPI from SDC in the emulator code so that I can reuse
sdc.c. This is what is done here.

With KEY and EMIT being switch words, most of the high layer can
be defined before drivers.

In addition to this change, I've compacted core blocks which were
becoming quite sparse.

It works (in emulation, but soon on real hardware!), but the LIST
command is awkward due to tight screen estate...

I'm about to reuse sdc.c in sms.c and the old directory structure
was becoming awkward.

De-macroisation negatively impacts speed, but this emulator doesn't
need to be fast. Clear code is more important.

We assume CPU_V20 configuration at all times.

I had forgotten that heads index increment before track index.

Getting a Collapse OS prompt.

I'm planning on adding other subfolders. 8086 for example...

libz80 doesn't move much anymore, there not much advantage to the
git module indirection.

I thought it wasn't possible with XCB to transform keycodes into
symbols for the current keyboard mapping, but I hadn't looked
hard enough.

Use reg 2 as specified.

Very very simplistic, but works with our driver.

The idea is to consider assemblers as "runtime" apps instead of
placing them in the "bootstrap" section of the blocks. These apps
will be used for much more than bootstrapping.

Moved its documentation to doc/asm.txt and made its code blocks
more compact.

Working on programming AVR chips exposes a glaring omission in my
first design of the SPI Relay: not allowing multiple devices make
this task hard. I constantly have to unplug my SD card before, plug
the AVR chip holder, then play a bit, then unplug the AVR holder,
then replug the SD card...

My prototype for a SPI relay design is built, but I haven't tested
it yet. I need to adapt the code first, which is what I do here.

When the prototype is tested, I'll update the SDC recipe with a new
schema.

"-ansi" is not supported by tcc, but according to gcc
documentation, "-std=c89" produces identical behavior.

See: https://gcc.gnu.org/onlinedocs/gcc-3.4.2/gcc/Standards.html

Only its jump at 0x33 remains.

I've also fixed a strange offset oddity in 8086's (n) placement.
It was off by 2, but strangely, it ran properly. Anyway, now it's
fixed.

It's more descriptive this way. Also, I'll soon add a new HERESTART
config.

The stage binary is now there.

The C VM now runs the show.

Previously, recipes that began spitting binary contents before
loading block 282 would end up with VARIABLE code in their binary,
thus breaking them. We fix this by making this loading process
2-part.

It helps a bit with staging times.

Was previously referred to by name+find, which was wasteful.

This commit adds ?DUP IF guards to MOVE and MOVE- that make them exit
when u is 0. Without these guards a DO loop was executed 65535 times
instead of 0.

In particular, this fixes a crash when "105 LOAD I " is executed
immediately after boot. Block editor word "I" passes IBUF length (0)
to MOVE- and MOVE in this case, causing a crash.

I always keep it on myself. I can imagine it's especially useful to
newcomers.