[comp.sys.ibm.pc] int 16 diagnostic ???

awylie@pyr1.cs.ucl.ac.uk (09/12/88)

Hi,
   I recently picked up TSR.ASM from this group, it is an assembly package
which lets you write TSRs in Lattice C. However it uses interrupt 16 with
a funny value in the ax register as a 'diagnostic' which detects whether
the same TSR has already been loaded.
   I can find no mention of this use of int 16 in any technical doc at my
disposal. Could someone explain it please? Also, on my XT clone, although
the 'diagnostic' does work, it also requires a keystroke before it returns
(as one might expect for int 16!).

uucp:  andrew%uk.ac.ulcc.ncdlab@nss.cs.ucl.ac.uk
arpa:  andrew%ncdlab.ulcc.ac.uk@cunyvm.cuny.edu
BITNET:  andrew@ncdlab.ulcc.ac.uk
JANET: andrew@uk.ac.ulcc.ncdlab