= Machine comparisons =
*Spectrum (48K machine) has 48K RAM, approx 6.5k of this is screen. The Amstrad has 64K ram, approx 16K of this is screen.
*Spectrum and Amstrad both have a Z80 CPU.
The CPU runs at a similar speed (3.5Mhz in Spectrum, 4Mhz in Amstrad) (Note, both systems do not run at optimum speed due to waits inserted by the video hardware).
*Spectrum and Amstrad both have a bitmapped display.
*They have a similar screen size. Amstrad's screen can be reduced in size to match the Spectrum's (256x192). Normal display size on Amstrad is 320x200.
*Spectrum (128K model and later) and Amstrad both have an AY-3-8912 sound chip. (1.7Mhz clock for AY in spectrum, 1.0Mhz clock for AY in Amstrad).
*Spectrum 48K had a 1-bit beeper sound. Playing sounds through the beeper is very CPU intensive. The Amstrad doesn't have a beeper. The only way to simulate the beeper sound would be to convert it to AY sound.
*The size and aspect of the pixels in the Spectrum's bitmapped display are comparable to the pixels in Amstrad's mode 1 bitmapped display.
*The Spectrum's video ram takes approx 6K. The Amstrad's video ram takes 16K (approx 12K when screen is reduced).
*The Spectrum 48k can't do double buffering in hardware, the Amstrad can. (To fix this problem on Spectrum they stored a bitmap in ram which they drew to, and then wrote changes to the screen). On the Amstrad you can use hardware double buffering, but then you need to sacrific twice as much video ram (e.g. 2 x 16K).
*The Spectrum has a fixed palette of 16 colours (8 colours with bright versions of each making 16 in total). Amstrad has a palette of 27 colours. In mode 0 you can choose 16 of these, in mode 1 you can choose 4 of these, in mode 2 you can choose 2 of these.
*The Spectrum's screen is "attribute" based. Each 8x8 cell can be assigned a background and foreground colour (and both colours must either be non-bright or bright). There is also the choice to flash the colours. This colouring results in "attribute/colour clash" on the Spectrum. The Amstrad's screen doesn't have this, and there is no restriction on how the colours can be placed.
*The Spectrum can display all 16 colours on the screen. The Amstrad can only do the same in mode 0, but this has fatter pixels. If the CPC's mode 1 resolution is chosen, this is not possible because only 4 colours can be chosen.
*The Spectrum has 1 interrupt per 50Hz frame, the Amstrad has 6 in fixed locations through the frame.
*Normally Spectrum graphics is stored in 2 colours, which means 8 pixels for each byte. In Amstrad mode 1, each byte defines 4 pixels. So for the same graphics you often need twice the RAM on the Amstrad. (This is a case where graphics without transparency are used). If transparency is used, then the amount of data can be the same.
*Neither had hardware sprites, therefore you have to use the CPU to both draw and erase the sprites.
*Amstrad has hardware scrolling, Spectrum does not.
===Consequences===