Product specifications

If you wish to locate the colour table at address 0K then bit 7 of register

3 must be set to 0. If you wish to locate the colour table at address 8k

then bit 7 of register 3 must be set to 1.

In both cases bits 6 to 0 must be set to 1's. This set-up is also shown in

the table below.

Locate colour table Load register 3

at VRAM address with data byte

OK - £0000 – 0 Decimal 127 Dec - £7F Hex

BK – £2000 – 8192 Dec 255 Dec - £FF Hex

The colour table is 6144 bytes long in graphic mode.

Graphic 2 mode colour table creation is described in much greater depth

in section 2.4.

This is where the patterns of the characters for the various modes are

held. It is a 3 bit value and therefore has a range of 0 to 7. It must not

exceed this value.

Bits 7,6,5,4 and 3 must be set to 0.

In all graphic modes except graphic mode 2, this table is located on a 2K

boundary. This gives 8 possible positions in which it can be located in

VRAM. The start address is determined by the contents of this register

times 2K.

If for example we wished to locate this table at address 8k (£2000 Hex)

in VRAM, we would load register 4 with 8k divided by 2K which is 4.

In graphic 2 mode this table is located on an 8k boundary as in the

graphic 2 mode for register 3.

Bits 1 and 0 must be 1. If bit 2 is 1 then the pattern generator table will

be located at address 8K . If this bit 2 is 0 then the table will be located

at 0K.

This set-up is also shown in the table below.

Locate pat gen table Load register 4

at VRAM address with data byte

OK - £0000 – 0 Decimal 3 Dec - £03 Hex

8K - £2000 – 8192 Dec 7 Dec – £07 Hex