If you want to continue the search further, Harris has
online data
sheets for much of the CDP18XX series (including the classic 1802
interface and memory parts), and maybe one of these will have a file
number for an 1801 data sheet. After you get a file number, you can
usually have the folks at Harris fax the data sheet to you.
I have full 1802 docs from back when the elf article was published.
The 1801 series was a less dense (hence teo chips) version of the 1802
and was discontinued with the advent of the 1802 back around '76. Harris
never supplied the 1801 and was a late supplier of the 1802.
Allison