1 EXHIBIT 10.11(d) PAUL G. ALLEN 110 110th Avenue, N.E., Suite 550 Bellevue, Washington 98004 September 1, 1999 Charter Communications, Inc. 12444 Powerscourt Drive, Suite 400 St. Louis, Missouri 63131 Re: Investment in Charter Holdco Concurrently with IPO Gentlemen: This will confirm that I will invest an additional $750,000,000 in Charter Communications Holding Company, LLC, concurrently with the initial public offering of Charter Communications, Inc. as described in CCI's Registration Statement on Form S-1 filed with the Securities & Exchange Commission on July 28, 1999. This commitment will expire if the aforementioned initial public offering is not consummated by December 31, 1999. /s/ Paul G. Allen ----------------------------------- Paul G. Allen