Commodore Amiga A1000, Hardware Reference Manual

Page: 287 / 380

SERPER 032 W P Serial port period and control
This register contains the control bit LONG referred to
above, and a 15-bit number defining the serial port
baud rate. If this number is N, then the baud rate is
1 bit every (N+1) * 0.2794 microseconds.
BIT# SYM FUNCTION
--------------------------------------------------------------
15 LONG Defines serial receive as 9-bit word.
14-00 RATE Defines baud rate=1/ ( (N+1) * 0.2794 microsec.
SPRxCTL 142 W A D Sprite x vert stop position and control data
SPRxPOS 140 W A D Sprite x vert-horiz start position data
These two registers work together as position, size and
feature sprite-control registers. They are usually loaded
by the sprite DMA channel during horizontal blank;
however, they may be loaded by either processor at any time.
SPRxPOS register:
BIT# SYM FUNCTION
------------------------------------------------------------------
15-08 SV7-SV0 Start vertical value. High bit(SV8) is in SPRxCTL
register below.
07-00 SH8-SH1 Start horizontal value. Low bit(SH0) is in SPRxCTL
register below.
SPRxCTL register (writing this address disables sprite horizontal
comparator circuit):
BIT# SYM FUNCTION
------------------------------------------------------------
15-08 EV7-EV0 End (stop) vertical value low 8 bits
07 ATT Sprite attach control bit (odd sprites)
06-04 X Not used
02 SV8 Start vertical value high bit
01 EV8 End (stop) vertical value high bit
00 SH0 Start horizontal value low bit
SPRxDATA 144 W D Sprite x image data register A
SPRxDATB 146 W D Sprite x image data register B
These registers buffer the sprite image data. They are
usually loaded by the sprite DMA channel but may be
loaded by either processor at any time. When a
horizontal comparison occurs, the buffers are dumped
into shift registers and serially outputted to the
display, MSB first on the left.
NOTE: Writing to the A buffer enables (arms) the sprite.
Writing to the SPRxCTL register disables the sprite.
If enabled, data in the A and B buffers will be outputted
whenever the beam counter equals the sprite horizontal
position value in the SPRxPOS register.
SPRxPOS see SPRxCTL
- 278 Appendix A -