gosia by SIMurai
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SIMurai Presents
(A Farewell Demo For)
Gosia
Size ... : .................. 462377 B
Date ... : ................ 2024-08-30
Party .. : ............... Xenium 2024
Compo .. : ...................... Wild
Platform : ..... 2x sysmoISIM-SJA5-S17
GFX .... : ................... fefinha
MSX .... : ........ eightbm & Tomarkus
CODE ... : ................... 1935711
This is a SIM card demo! This means
that all the computation and storage
needed to produce the visuals and
audio, came directly out of SIM cards
in real-time. We are actually using 1
card for graphics, and 1 card for
audio, all working together in
parallel to produce 3:3:2 (8 bit)
video and 11025 Hz unsigned 8 bit
audio.
XXX: The total size can vary +/- 10 B.
This is caused by the compiler used
for the Java Card applets. The
calculated total size consists of all
files installed on the cards, this
means the host app size was excluded.
The host does not contribute to the
audio or video of the demo (it only
streams the video/audio from the
cards), therefore we believe this to
be a fair choice.
Each frame of video is generated by 1
SIM card, half a frame at a time due
to packet size limitations (we can
only send 256 byte of data at a time).
When we recorded the presentation/
video, we actually mentioned needing 4
cards, but with some optimization done
after the party, we did get it
comfortably down to just 1 card.
There are many effects that are merely
a glorified animation, as we do some
mirroring to save on flash space (we
know, boooo!), but others, like the
hourglass, are created by layering
multiple sprites, with simple
transparency, motion, and mirroring.
All the sprites were designed in
Aseprite.
Developing for the SIM card comes with
certain challenges: The card OS wants
you to behave nicely, the cards have
little RAM and flash, flash memory has
a limited number of write-cycles, you
need to use Java Card (a restricted
version of Java), installing apps on
cards takes a long time, etc... The
card often decides what it will and
will not allow, and so very often the
card returns an internal error (2 byte
status word), with no further
explanation. Since the SIM card is a
secure element, debugging and data
extraction are quite tricky, as the OS
tries to ensure that the app does not
attack the card OS itself. In fact, we
never found a good way to debug code
running on the card, therefore we
opted to using a self-made SIM card
emulator to test the Java code while
it runs on a PC.
This demo has been the collaborative
effort of Tomarkus, fefinha, eightbm,
and 1935711, a.k.a., SIMurai. It was a
"wild ride" getting this demo ready
for your viewing pleasure.
Unfortunately, during the development
of some early tests, tooling, and
experiments, Gosia, my (1935711) aunt,
passed away. An endlessly cheerful and
pleasant person, with a distinctly
contagious laughter and wonderful
cooking skills (seriously delicious!).
This demo does not have a single clear
theme, but we combined different
elements to create something
interesting and colorful---something
we hope Gosia would have enjoyed.
============ Instructions ============
Please read the instructions at
`/install/README.md` (inside the src
release). They explain how to build
tools and the demo, how to install the
demo on SIM cards, and how to run the
demo.
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