Product specifications

The pat gen table is 6144 bytes long in graphic 2 mode.
Graphic 2 mode pattern generator creation is described in much greater
depth in section 2.4.
Register 5 SPRITE ATTRIBUTE TABLE BASE ADDRESS is the start address for a
128 byte block which contains position, colour and shape information, for
each of the 32 sprites which it is possible to enable.
The sprites are active in all modes except text mode.
This register value occupies 7 bits and therefore has a range of 0 to 127.
Bit 7 must be set to 0. The sprite attribute table is located on a 128 byte
boundary. If we wished to locate this table at say address 6K (£1000
Hex - 6144 Dec), we would have to divide our desired decimal start
address by 120 (or our desired hex address by £80), and then place the
result in register 5. In this case the correct resulting byte is shown in the
table below.
Desired address Divide by Result
Dec 6144 128 48
Hex 1800 £80 £30
For a fuller description of the sprite attribute table please see section 4.
Register 6 SPG BASE ADDRESS is the sprite pattern generator base address.
It holds a library of sprite shapes which can be 'called up' by one of the
control bytes in the sprite attribute table. This means that to change a
sprite shape to another existing pattern it is only necessary to change
one byte in VRAM.
This table is a maximum of 2043 bytes long, and is divided into 256
blocks of 8 bytes each.
The register value for this table occupies 3 bits and therefore has a
range of 0 to 7. It must not exceed this range. Bits 7,6,5,4 and 3 must all
be set to 0.
The table is located on a 2K boundary so if we wished to locate this table
at say address 14K, all we have to do is divide the desired start address
for this table by 2K to obtain the correct byte to load into register 6. In
this case 14K divided by 2K = 7.
For a fuller description of the sprite pattern generator table please see
section 4.