I'm going to put it on my list of projects to create a CPU card for my Microtutor that uses the 1802 instead I think.? I can get some blue PCB stock.? As far as I understand the 1802 is fully backward compatible. Maybe the 1801s will show up on day.? I've found all kinds of chips I was told were impossible to locate. Sent from my Samsung device -------- Original message -------- From: Steven Feinsmith <steven.feinsmith at gmail.com> Date: 2017-10-20 7:32 PM (GMT-08:00) To: Brad H <vintagecomputer at bettercomputing.net>, "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: CDP1801 RCA 1801 disappeared from face of Earth forever... You would be better off to purchase at: http://www.sunrise-ev.com/membershipcard.htm to use 1802. The 1802 was very successful microprocessor that replaced 1801 because it required to have a pair of chips to work together. I believe I saw 1801 was more than 30 years ago. Good luck! Steven On Wed, Oct 18, 2017 at 9:45 PM, Brad H via cctalk <cctalk at classiccmp.org> wrote: Hi there, I just purchased an RCA Microtutor minus the rather important CPU card.? I can recreate the card but I expect locating the 1801 chips will be difficult.? I am just posting this in various forums in case anyone has any leads on where I might find either the complete card or the required chips to make a replacement.? I'm wondering what, if any devices were built with the 1801 that I might be able to scrounge from. Thanks again, B