residents in iS-DOS

Hello, ALL!!! People, here I became very interested in how write a resident program for iS-Dos, which would be called via IM2? There is a book here: Programming in the environment IS-DOS, but somehow it’s not very clearly written... :( If anyone has dealt with this matter, please chime in a few lines please... Sincerely, Den Kosenkov PS: Maybe someone already has a CMOS driver? hours under iS-DOS? Well, so that there is always time displayed on the screen... -+- iOSif StALLin '45