RCA COSMAC Operator's Manual page 35

UT2 READ AND TYPE ROUTINES (cont'd)
Tables I and 2, given below, suamnarize the functions and
calling sequences for UT2 which have just been described.
Appendix B provides a detailed listing of the UT2 program.
Clobbered by UT2 while storing registers.
Pointer to RAM "work" byte. (UT2 uses R2=O)
Program counter for all READ, all TYPE and
TIMALC routines.
Program counter for VTZ (which calls the
routines above).
Program counter for the DELAY routine.
Points to DELAYI in memory.
Assembled into by READAH (input hex digits).
AUX.l holds time constant and echo bit.
AUX.O used by all READ, TYPE routines and
hy TIMALC.
CHAR.I holds input/output ASCII character.
CHAR.O used by all READ, TYPE routines and
by TIMALC.
REGISTER REGISTER
NAME NUMBER
PTER RO
}
CL RI
ST R2
SUB R3
PC RS
DELAY RC
ASL RD
AUX RE
CHAR RF
SUMMARY OF UT2 FUNCTIONS AND CALLING SEQUENCES:
FUNCTION/COMMENTS
TABLE I - VT2 REGISTER UTILIZATION
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