Sinclair ZX Spectrum User Manual (English)

To Next Page

To Previous Page

Chapter 4

Full cell

In basic colours mode using single byte colour, each attribute cell is formatted in the

standard Spectrum manner as follows:

Ink, ordered as GRB

Paper, ordered as GRB

1=Bright

1=Flash

The ink bits define the colour used for those pixels that are set in the display file, and

the paper bits define the colour used for those pixels that are reset. Both values are

composed of 3 bits, yielding a range of 8 colours for each. When coupled with the

bright bit a total of 16 different colour values are produced, although only 15 of these

are unique since black and bright black display the same. When the flash bit is set, the

paper and ink colours swap over at a fixed frequency of 1.565 Hz.

In basic colours mode using double byte colour, the first attribute byte defines the ink

colour and the second attribute byte defines the paper colour. Both bytes are

formatted as follows:

Colour, ordered as GRB

Unused (available for program use)

1=Bright

1=Flash

The format encodes the ink and paper using 3 bits each, yielding both a range of 8

colours. The bright bit in each byte extends these totals to 16 different colour values,

although only 15 of these are unique since black and bright black display the same.

With the flash bit in both attribute bytes set, the ink and paper colours swap over at a

fixed frequency of 1.565 Hz and replicate the flash mode of the standard Spectrum

display. However, if only the ink attribute byte’s flash bit is set then just the ink coloured

pixels swap between the ink colour and the paper colour, and if only the paper

attribute byte’s flash bit is set then just the paper colour pixels swap between the

paper colour and the ink colour.

Note that the unused bits of each colour byte are available for use as storage by a

program. They could, for example, be used in a maze game to hold flags that indicate

Other manuals for Sinclair ZX Spectrum

Need help?

Do you have a question about the Sinclair ZX Spectrum and is the answer not in the manual?

General

Processor	Zilog Z80A
Clock Speed	3.5 MHz
RAM	16KB or 48KB
ROM	16KB
Graphics	256 x 192 resolution
Sound	1-channel beeper
Storage	Cassette tape
Input	Keyboard
Power	9V DC
Release Year	1982
Display	TV via RF modulator
Ports	Expansion, RF
Colors	15 (8 colours with two levels of brightness each, plus black)