Attention: please don't be scandalized by the poor, not technician explications written in this chapter, because the objective would be an easy explication  for everybody.

- Colours -

If you have just seen the "levels" chapter and you said:"Pfh, so few colours!", probably you are a C64 user.

At the moment I don't know if we'll use different colours for background graphics, or different coloured level zones (do you remember C64's Armalyte levels?), but it's almost sure that sprites (your ship, ship's explosions, enemies...) will be coloured in the same colours, and background too.

You must know that Plus/4 has no hardware sprites!

Armalyte, © Thalamus

In order to avoid talking  too technician, the C64 hardware sprite management allows to use several colours  without clashes, as you can see in the game screen extract to the left.

	Gwnn, © Mastertronic		Championship Wrestling C16, © US Gold

C16-Plus/4 games using sprites, then, must:
-1) use same colours for sprites and background (see figure 2);
-2) use several colours but accept the consequent colour clash (see figure 3);
-3) use characters and not real sprites, but we don't care here.

 - Graphics & Memory -

OK, now we know that Plus/4 has no hardware sprites...so, what can we do? We can code a routine managing software sprites.

Using 2 character banks, a part of one has to be used in 'mixing' our sprite with the actual background characters which are moving in that moment into its square space. After overlapping the ship to the background, the whole square will be printed on the screen.

Do you noticed how much waste of memory? The worst consequence is that a big slice of the characters bank (256 chars) has to be used for sprites. If you think that another part of the bank is occupied by pinned graphics (broken turrets, explosion graphics for turrets, weapons, fonts), you can imagine in which little space we have to condense both background and the end level big enemy's graphics!

- Music & FX -

We will use for sure the SIDcard technology.

Plus/4 users know it since years: the SIDcard permits you to insert the famous C64 SID chip into the black box. In this way, you can listen cool music (not the poor TED sound) without assigning too much work to your CPU. Often, nowadays any  emulator shows its 'SIDcard on' option.

If possible, I would insert a frequency converter: your Plus/4 will read the 3-voices music but it will play a channel with a TED voice and both the remaining two, quickly alternating, with the second TED voice. Not much quality...but you can hear it, what the hell! It's quite fast and may be done.

Another ambitious solution has been recently achieved: both SIDcard for the music and TED sound for effects, with adjustable indipendent volumes by pressing keys F1/F2 and F3/HELP. If nothing changes, that will be the definitive solution.

At this point, the critical variable is the space: how many musics can I insert, is there enough space for the frequency converter? Well, actually I composed a whole 4K block for the 1st level, and I'd found lotta difficulties, because of the short memory: the level's music can't be so complex as I would, nor so much long in playtime. So, I must direct my efforts toward the melody and avoid complicate and original sounds, that waste much memory.