Atari 400 Technical Reference Manual page 191

CIO/Handler interface Parameters
G13 ZIOCB (IOCBAS)
G14
ICHIDZ
G15
ICDNOZ
G16
ICCOMZ
Q17
ICSTAZ
G18ICBALZ,ICBALH
G19 ICPTLZ, ICPTHZ
G20 ICBLLZ, ICBLHZ
Q21
ICAX1Z, ICAX2Z
Q22
ICSPRZ (ICIDNO,CIOCHR)
Internal working variables
G23
ICCOMT*
G24
ICIDNO*
Q25
CIOCHR*
H. Serial I/O routine (SID)
User call parameters
Hl DCB control block
H2 DDEVIC
H3 DUNIT
H4 DCOMND
H5 DSTATS
H6 DBUFLO,DBUFHI
H7 DTIMLO
H8 DBVTLO,DBVTHI
H9 DAUX1,DAUX2
Bus sound control
Hl0 SOUNDR
Serial
bus
control
206
Retry logic
Hll CRETRV*
H12 DRETRV*
Checksum
H13 CHKSUM*
H14 CHKSNT*
H15 NOCKSM*
OPERATING SYSTEM C016555 -- Appendix L