View Full Version : Cosmac Elf RCA CDP1801ACE

April 14th, 2011, 03:48 PM
Hi, I'm in the progress of building a Cosmac Elf and the processor I have is an CDP1802ACE instead of the regular 1802. Is there much of a difference between these two chips? I'm having a hard time telling if the datasheets I'm looking at are the right ones. Also another quick question while I"m here. The article calls for a 30pf capacitor but I have 33pf capacitors. Will they work?

Sorry if this is the wrong section

EDIT - I mean 1802 not 1801 sorry, typo

April 14th, 2011, 05:26 PM
Is the 30 pF capacitance for the crystal oscillator? If so, 33 pF should be fine. Most ceramic caps I use are 10% anyway, so you might end up with a cap marked 33 that measures 30, or a cap marked 30 that measures 33.

April 14th, 2011, 05:49 PM
Yes it is and awesome. With the exception of the processor not being exactly an 1802 those were the only parts that wasn't 100% what the document called for.

Any idea what's the difference between the processors are?

April 14th, 2011, 06:33 PM
I think the CDP1802ACE is just the Intersil part number...same pinout/instruction set, but probably a more modern die. Since it's Intersil, it /may/ be one of the radiation-hardened Silicon-on-Sapphire 1802s like the military/NASA used.

April 14th, 2011, 07:05 PM
Ah ok, thanks! I'm looking forward to building this computer.