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| | RCA COSMAC 1801
General
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General Information
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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
designer of the microprocessor that came to be known as the 1800 series was
Joe Weisbecker. He was inspired by the Intel 4004 and
built his own microprocessor at home with TTL logic. When Jerry Herzog,
learned of his work, he brought him into his group at the RCA Laboratories
and he worked with his logic designers to create the 1801, 1802 etc.
The COSMAC CDP1801 is implemented with the CDP1801R Microprocessor
Register and CDP1801U Microprocessor Control. The segregation of function
was necessary due trace size limitations, so the "R" provided ALU
functionality and the "U" 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 processor's 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 COSMAC was the
first microprocessor in space. The 1801 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.
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Production
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Early 1975 |
| Designers |
Lead Designer: Joe Weisbecker, Team Lead: Jerry
Herzog |
Architecture
| Type |
Data Word |
Address Space |
Clock |
Instruct- ions |
Assists |
Reg's GP |
Reg's Math |
Reg's Index |
IO Ports |
Stack |
Interrupts |
Memory |
| 2 Chip
CPU, CMOS |
8-bit |
64K |
2Mhz, 4Mhz |
59 |
NA |
16x16-bit or 32x8-bit |
1 |
NA |
8 |
Ext RAM |
1 Level |
NA |
Packages
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Chip Name |
Package
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On-Chip Identification |
Picture |
General Comments
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| CDP1801RD |
White, silver lid, 28 gold side braised Leads |
CDP1801RD |
 |
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| CDP1801UD |
White, silver lid, 40 gold side braised Leads |
CDP1801UD |
 |
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| CDP1801RD |
White, gold lid, 28 gold side braised Leads |
CDP1801RD |
|
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| CDP1801UD |
White, gold lid, 40 gold side braised Leads |
CDP1801UD |
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| CDP1801CRD |
White, gold lid, 28 gold side braised Leads |
CDP1801CRD |
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"C" suffix versions have a lower
voltage range: 4V to 6.5V. Max clock was limited to 2Mhz. |
| CDP1801CUD |
White, gold lid, 40 gold side braised Leads |
CDP1801CUD |
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Related Chips
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Related Chips
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RCA 1802,
RCA 1804, RCA 1806
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Second Sources |
None |
| Support Chips |
1852
(8-bit I/O Port), 1854 (UART), 1856 (4-bit memory buffer), 1857 (4-bit I/O
buffer)
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