Commodore Amiga - Specifying the Register Contents

15
987
o
o 0 0 0 0 0 0 1 j.-- 8 bits data ~I
Data gets shifted out this way.
Figure 8-4: Starting Appearance of SERDAT and Shift Register
15 987
o
o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
--".1 1
----------------- one bit
All zeros from last shift-
Figure 8-5: Ending Appearance of Shift Register
The register stops shifting and signals "shift register empty" (TSRE) when there is a 1
bit present
in the bit-shifted-out position and the rest of the contents of the shift regis-
ter are
Os. When new nonzero contents are transferred into this register, shifting begins
again.
SPECIFYING THE REGISTER CONTENTS
You should write the data you wish to transmit as the low 8 (or 9 if you wish) bits of
this
output register (SERDAT). Above the data bits (in bits 8 and above or bits 9 and
above) you write 1 bits for however many stop bits you transmit with the data.
244 Interface Hardware