RCA CDP1801RD and CDP1801UD

Most microprocessor collector's are familiar with the RCA COSMAC 1802. The 1802 was RCA's first single chip microprocessor. As a footnote it is mentioned that the 1802 is a single chip implementation of the two chip 1801. The first COSMAC and RCA's first microprocessor is the CDP1801 (and the world's 1st CMOS microprocessor). The COSMAC CDP1801 is implemented with the CDP1801RD Microprocessor Register and CDP1801UD Microprocessor Control. The segregation of function was necessary due to trace size limitations, so the RD provided ALU functionality and the UD providing the control unit functionality.

The fundamental architecture and technology of the 1801 was the same as the CDP1802. It was silicon gate CMOS and had similar packaging. The 1801 was slower at 2Mhz initially and then 4Mhz (1802 at 6.4Mhz). The 1802 (91 Op Codes) added many instructions, but was software compatible with the 1801 (59 Op Codes). The 1802 instruction additions beefed up the processors math and branching capabilities. The COSMAC architecture is classified as 8-bit (accumulator was 8-bits). However, the registers were 16-bit (and 8-bit) and processor had 16-bit addressing. The register oriented architecture made for very clean efficient programming. 

The 1801 was introduced in early 1975 and the 1802 in early 1976. The 1801 microprocessor and the COSMAC architecture were the first based on CMOS chip technology. CMOS chips could be suspended to save battery life, operated in extended temperature ranges, and were more tolerate of electronic interference. It is no wonder that the 1802 (SCP-234) was the first microprocessor in space. It was aboard the Defense Meteorological Satellite Program 5D-1 spacecraft launched in 1976. The 1801 was also used on spacecraft and flew on an OSCAR satellite launched in 1978. Other COSMAC spacecraft include UoSAT-1, UoSAT-2, Voyager (3 1802's), Viking, and Galileo. The COSMAC's that flew in space were space/radiation hardened versions using a CMOS/SOS chip technology. These radiation hardened versions were developed in conjunction with the Sandia National Laboratories.

While only a few hundred COSMAC's flew in space, they had wide commercial use. For example, they were used in Chrysler electronic ignitions, RCA and Radio Shack video games, RCA video terminals (VP3301 & 3), Elf computers, and ETI-660 computers (some sources list the Dream 6800, but it was MC6800 based). The COSMAC Elf was introduced as hobbyist's project computer in 1976 in a series of Popular Electronics magazine articles. RCA latter developed its own "Elf" named the COSMAC VP-111 (shortened to VIP). The Elf still has a large following and many websites are dedicated to it. The 1802 led the microprocessor market in shipments at it peak popularity in 1977.  

I am offering the these two chips, the CDP1801RD and CDP1801UD, for sale.  These two chips are incredibly rare, but to find these in unused new-old-stock condition is unique. The 1801 was intended for commercial use and was sort of a production prototype. Very few of these processors are available and to my knowledge this is the only set available for sale.

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