M69000 Asiliant Technologies, M69000 Datasheet - Page 327

• Manufacturer Part Number: M69000
• Manufacturer: Asiliant Technologies

Specifications of M69000

• Lead Free Status / Rohs Status: Supplier Unconfirmed

D-2
Hardware Cursor and Pop Up Window
Base Address for Cursor Data
The Cursor 1 Base Address Low Register (XRA2) and the Cursor 1 Base Address High Register (XRA3)
are used to program the base address in the frame buffer at which the cursor data for cursor 1 begins. The
Cursor 2 Base Address Low Register (XRAA) and the Cursor 2 Base Address High Register (XRAB) provide
this same function for cursor 2. The base address values stored in these registers actually specify an offset
relative to the base address at which the frame buffer begins.
The amount of space allocated for cursor data for each cursor is 4KB. More than one cursor pattern may
be stored within this space, depending on the cursor size. While the bits in both the high and low base
address registers for each of the cursors are combined to provide the base addresses, the upper four bits
of each of the low base address registers (XRA2 for cursor 1 and XRAA for cursor 2) are used to select
which of the available patterns stored within each space is to be used for each of the cursors. In the
32x32x2bpp AND/XOR pixel plane mode, up to sixteen 256 byte patterns can be stored in the 4KB memory
space, and all four of the upper bits of the low base address registers are used to select one of these sixteen
possible patterns. In all three modes with a cursor resolution of 64x64 pixels, up to four patterns of 1KB in
size can be stored in the 4KB memory space, and the uppermost two of these four bits are used to select
one of these four possible patterns (the other two bits should be set to 0). In both modes with a cursor
resolution of 128x128 pixels, only up to two patterns of 2KB in size can be stored, and only the uppermost
bit of the four bits is used to select between them (the other three bits should be set to 0).
Cursor Vertical Extension
The cursor vertical extension feature allows the vertical size (height) of either cursor in any of the six
possible modes to be altered from the height normally dictated by the choice of cursor mode. The cursor
mode still determines the width of the cursor. This feature allows the cursor to have a non-square shape.
This feature is enabled via bit 3 of either the Cursor 1 Control Register (XRA0) for cursor 1 or the Cursor 2
Control Register (XRA8) for cursor 2. Once enabled, the height of the given cursor must be specified --
either in the Cursor 1 Vertical Extension Register (XRA1) for cursor 1 or in the Cursor 2 Vertical Extension
Register (XRA9) for cursor 2.
Total size of the cursor data for a given cursor can not exceed the 4KB allotted for the cursor data of each
cursor. This places a limit on the height of a cursor of given width and color depth. This also has
implications concerning how many patterns may be stored in this space for the given cursor, and the
mechanics of selecting which of those patterns is to be displayed using the upper four bits of the low base
address register for each cursor.
Cursor Colors
The colors for drawing each of the two cursors are specified in two sets of four alternate color data positions
added to the RAMDAC (positions 0-3 for cursor 2 colors 0-3, and positions 4-7 for cursor 1 colors 0-3).
These alternate color data positions are accessed using the same sub-addressing scheme used to access
the standard color data positions of the main RAMDAC palette, but with bit 0 in the Pixel Pipeline
Configuration Register 0 (XR80) set so that the alternate color data positions are made accessible in place
of the standard positions.
If the use of a border is enabled, color data positions 6 and 7, which provide colors 2 and 3 for cursor 1, will
be taken over to specify the border colors for the CRT and flat-panel. This will limit cursor 1 to only colors
0 and 1. This limit on cursor 1 will not impact either of the AND/XOR pixel plane modes, or either of the
cursor modes with a cursor resolution of 128x128 pixels because none of these four modes use cursor
colors 2 or 3.
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69000 Databook
Subject to Change Without Notice
Revision 1.3 8/31/98