Qué (quién) es CDP1802 - definición

8-BIT CMOS MICROPROCESSOR

CDP1802; RCA COSMAC; COSMAC 1802; CDP 1802; CDP 1801; Flexible Recreational Educational Device

CDP1802

RCA 1802

RCA 1802

<processor> An extremely simple microprocessor fabricated in CMOS, running at 6.4 MHz at 10V (very fast for 1974). It could be suspended with the clock stopped. It was an 8-bit processor, with 16-bit addressing. Simplicity was the primary design goal, and in that sense it was one of the first RISC chips. It had sixteen 16-bit registers, which could be accessed as thirty-two 8-bit registers, and an accumulator D used for arithmetic and memory access - memory to D, then D to registers and vice versa, using one 16-bit register as an address. This led to one person describing the 1802 as having 32 bytes of RAM and 65535 I/O ports. A 4-bit control register P selected any one general register as the {program counter}, while control registers X and N selected registers for I/O Index and the operand for the current instruction. All instructions were 8 bits - a 4-bit op code (total of 16 operations) and 4-bit operand register stored in N. There was no real conditional branching, no subroutine support and no actual stack but these could be implemented by clever use of registers, e.g. changing P to another register allowed jump to a subroutine. Similarly, on an interrupt P and X were saved, then R1 and R2 were selected for P and X until an RTI restored them. The RCA 1805 was an enhanced version. The 1802 was used in the COSMAC (VIP?) microcomputer kit, some video games from RCA and Radio Shack, and the ETI-660 computer. It was chosen for the Voyager, Viking and Galileo space probes as it was also fabricated in {Silicon on Sapphire}, giving radiation and static resistance, ideal for space operation. More history (http://cosmacelf.com). (2002-04-09)

Wikipedia

RCA 1802

The COSMAC (Complementary Symmetry Monolithic Array Computer) is an 8-bit microprocessor family introduced by RCA. It is historically notable as the first CMOS microprocessor. The first production model was the two-chip CDP1801R and CDP1801U, which were later combined into the single-chip CDP1802. The 1802 represented the majority of COSMAC production, and today the entire line is known simply as the RCA 1802.

The processor design traces its history to an experimental home computer designed by Joseph Weisbecker in the early 1970s, built at his home using TTL components. RCA began development of the CMOS version of the processor design in 1973, sampling it in 1974 with plans to move to a single-chip implementation immediately. Jerry Herzog led the design of the single-chip version, which sampled in 1975 and entered production in 1976.

In contrast to most designs of the era, which were fabricated using the NMOS process, the COSMAC was implemented in CMOS form and used static logic. This allowed it to run at lower power settings and even be stopped completely; in addition it would run cooler and not generate as much heat as NMOS chips. RCA referred to its CMOS process as "complementary silicon/metal-oxide semiconductor", giving rise to the acronym COS/MAC, which was then backronymed to "complementary-symmetry monolithic-array computer" when referring to the processor. RCA also produced radiation hardened versions using a silicon on sapphire process, which found use in the aerospace field. These remain in use to this day, and as of 2008 continued to be produced by Renesas (formerly Intersil).

Successors to the 1802 are the CDP1804, CDP1805, and CDP1806, which have an extended instruction set, other enhanced features (like on-chip RAM and ROM, and built-in timer), with some versions running at faster clock speeds, though not a significant speed difference. Some features are also lost, like the DMA auto-boot loader functionality. There are also some minor pin function changes, but the line continues to be produced in its original 40-pin dual in-line package (DIP) format.

https://en.wikipedia.org/wiki/RCA 1802