http://scratchpad.wikia.com/wiki/ZX_Spectrum_technical_information
===Consequences of a Spectrum Port===
====Input====
The Spectrum has more joystick standards than the CPC, however reading the keyboard and joysticks and handling the input on the Spectrum is much simpler, takes less code and takes less CPU time than on the Amstrad.
On the Amstrad it is best to read the keyboard and joystick in one pass and store the data into a buffer which can then be queried later. Then read from this buffer when you need to check the inputs.
====Disc Loading====
The Spectrum +3's disc interface had a design that was close to the Amstrad CPC6128's. This meant that disc loading software that used the disc interface directly could be modified easily to be used on the CPC. There are disc versions of the Alkatraz, Hexagon and Speedlock loaders common to both the CPC and Spectrum.
The good thing is that both shared good disc interfaces, so a disc loading system on the Spectrum, if ported to the CPC would not be a bad thing.
====Tape Loading====
Both the Spectrum and Amstrad had a similar method for loading or saving on cassette. For both it is CPU intensive and for both the method of representing the 1 or 0 bits is the same.
Some CPC games used the original block loader which meant loading took much longer compared to Spectrum, some used the firmware headerless block loader (CAS READ) which was a bit faster, and some CPC games used a modified Spectrum tape loader (extracted from the Spectrum's ROM and modified for the Amstrad's hardware).
Sometimes the Spectrum loader was modified for the CPC without exact knowledge of how it worked, this resulted in some games with bad loaders that either didn't check for errors, or which didn't work in some circumstances. This lead to unreliable loading.
* Aliens (UK version, original release).
====Colours====
The Spectrum palette (15 colours, bright at bottom):
* Recolour the graphics using the Amstrad's palette to improve the look.
====Colour Clash from the Cell based colouring====
The cell based colouring used on the Spectrum has its disadvantages. [[image:clash.png|right|thumb|Colour clashing in Knight Tyme. Observe the appearance of the character sprite as it merges with the background. (Background colours have priority here in this game.)]]