В деме First Association Preview:
http://zxaaa.untergrund.net/view_demo.php?id=5025

в эпилоге приведены требования к eurodemo:

First Association is marked as "eurodemo". That means
this demo should work on all known manufactured speccy
clones. On the next page are some tech details about
compatibility. Parts written on (for ex.) Pentagon must
run correctly on Timex and vice versa. We find off opti-
mal software rules to fly-over hardware differences.

F.A. is demo for 48k (+ sound chip) or 128k machines.
In so huge project multiloading is the only one way to
make this demo possible. Also due to this fact, we don't
need to care about the storage system you use, because
all will be controlled by BASIC commands.

Organization of F.A.: 48k and 48/128 parts will be
before "only 128" parts. The last 48k part will be able
to skip only on 128k then all the rest will follow.

Speed of CPU: From eastern europe came some demos
that was designed for faster spectrums. Due to this fact
all this demos are too slow on normal spectrums (UK).
F.A. will not accept parts which will slow down due to
the CPU speed. 48k has 69900 tacts per frame (Fast mem)
128k has 70920 tacts per frame (Fast mem). In the slow
memory (CHIP) both computers slowes down about 15%.
(note: +2A has a bit faster CHIP memory).

MEMORY:
#Fast Memory#(48) 8000H to ffffH
# # (128) pages 0,2,4,6 (c000H to ffffH)
# # (+2,+3) pages 0,1,2,3

#Chip Memory#(48) 4000H to 7fffH
# # (128) pages 1,3,5,7 (c000H to ffffH)
# # (+2A,+3) pages 4,5,6,7

PORTS (128k):
Paging is on port 7ffdH,value (prefer) or fdH,value
with set 6-th bit. Before you initialise music, set all
(14) AY-Registers to zero value. This is necessary for
Timex (else crashes).

INTERRUPT:
Never (!!!) set interrupt vector to the slow memory.
This causes very ugly (hard to describe) effect which
looks like 'RAIN' on the screen. On some worse spectrums
(old +2 models) it causes also crashing of the program.
This is hardware problem and can be fix only with setting I-register to Fast mem. Avoid this!

Other rules and summary:

#48k speccy:
- start and loading at address 25000
- PUSH ALL registers before starting your part and
POP'em back when return to BASIC
- Your part must correctly return to Basic.
- Do not use any 'special' hardware.
- Do not use IN A,(ffH) for timing. This doesn't work
on +2A and +3.
- Multicolors try to synchronize for all spectrum
types you can. Make speed self test.
- Music should be synched with the visual effects.
- Set correctly interrupt vector (only Fast mem). Make
whole vector table if possible.
- Reset all AY registers before init music.
- Mention by any form that it beholds to F.A.

#128k speccy:
- Everything as we wrote for 48k.
- Watch out ports and interrupt.
- Do not use +3's 64k paging.
- Pack all used pages to a several files starting at
25000.