Hello
Thanks everybody for replies.Then I am not alone.
Booting from Dos disk is not enough - much lower speed (MHz) is reqd.Waiting for Kai Klass to answer.
Meanwhile some fundamentals:
1)Any objection using LM317T for generating reqd. programming voltage?
2)Why PNP transistors (2907)for swiching?Can I use 4066/4051 types?Then switching 7805 or 7812 for
Vpp is easier and I dont(possibly) bother about logic high and low actual voltages.
3)317s genarate emi/noise.What is recommended physical separation practice,- from rest of the sensitive area of the circuit.
Incidentally,in my place(Kolkata-India) programmable regulator with shut down is apparently not available(Max667 type).Can somebody from India tell/enlighten me on this?
Mr Karas & Mr.Eric - Yes I think I have to go for ISP.
Would you kindly recommend cheapest chip (Eric from from your range of Atmel,Philips,Maxim)

Regards
A.S.Rudra