[comp.sys.ibm.pc] Int 28H not issued from keyboard loops invoked by int 21h, 3fh

vg55611@ihuxy.ATT.COM (Gopal) (03/18/88)

Normally an INT 28H is issued from keyboard wait loops when it is safe
to do file i/o using INT 21H calls.

However, no such interrupt seems to be issued if the keyboard is accessed
through the INT 21H, fn. 3FH with the file handle of 0 (std in).  Even
PRINT.COM suspends operations during this call.

Anyone know of any way safe way to do file i/o (from a TSR) during this call
using DOS ?  Considering that fn. 3fH is itself a file i/o call, is this
an impossibility ?

Thanks in advance for all responses.

Venu P Gopal
ihnp4!ihuxy!vg55611