COSMAC 1802 production

This Web page last updated date May 1 2018. This Web page describes and will accumulate information, about production marks on COSMAC 1802-family microprocessors and support devices, produced by RCA, Harris, Intersil, from the mid-1970's into the 21st century. There's also discussion of the origin of production, based on circumstantial evidence versus those markings. The marks are described as best information can be obtained. Thanks to Ian May for his detailed review and descriptions, and thanks to other participants, as posted in Yahoo's cosmacelf discussion group in April 2018.

Why bother? Because 21st century sources of these chips have erased and remarked them. Here's a Web page about the practice. That action obscures the origin and therefore the features and age of these COSMAC devices. Age and origin matters to chip collectors, purchasers in bulk, and purchasers who want specific performance.

Another referenced Web page will try to accumulate information about known-origin (and sometimes unknown-origin) devices, to build a kind of catalog of marks and features. This page will be long enough. - Herb Johnson

Summary markings, packaging

[1802 eject pin marks] [1802 eject pin marks]

RCA produced COSMAC 1800-family chips were typically marked on top as for example "CDP1802", with possibly one or two letters following designating performance and/or packaging. Then the letters "RCA" below, possibly followed by a letter. Then below that, some kind of numeric date-code, possibly followed by a letter. Under the chip, there were additional markings related to point of manufacture. The physical plastic package was molded, so there's also marks inside the circular indentations from "mold ejection pins".

COSMAC family parts were produced in different packages - plastic, ceramic, flat-pack - or as unpackaged dice. That packaging has one-letter ordering designations by RCA, and may be marked as noted above. Details are described and documented on this Web page.

RCA produced 1802's from about 1974 into the 1990's. Other companies produced them as well. In principle, combinations of markings correlate to specific times or production facilities. When markings don't "correlate", that suggests the package was remarked. Therefore, discussion ensued, followed by this Web page to "nail jelly to a tree". - Herb

Production versus purchase information

As noted in the introduction, COSMAC 1800 chips may be remarked. One way to detect, or avoid, remarked chips is to buy from reliable or production-documented sources. Another way, is to have purchased chips years or decades before the practice of remarking. In the course of discussing chip identification, it becomes useful or necessary to describe WHERE and WHEN the chips in discussion were obtained, and any other information of origin. Ian May, in cosmacelf Yahoo discussion, suggested a kind of nomeclature like "CL1 - you acquired the device long before [such practices]" and "CL3 - you bought it [used] from an eBay seller in a north Asian country", etc. I (Herb) find that confusing jargon, in the presence of even more alphanumberic jargon. And any seller, could have bought from any other seller, nevermind their location. I don't see any reasonable alternative, to a brief provable-fact description; such as "bought in 1978 with my SuperELF". I have chosen at this time, to not codify information about purchase, in this Web page, and use words instead. That may change over time, but for now, I think more information is better. - Herb

Identified RCA-brand markings

RCA performance markings

The marking "CDP18XX", XX some number, identifies of course the features of the chip, such as the CDP1802, CDP1854, etc. Following those marks there may be one, two or three alphabetic letters. No letters, identifies a specific Vcc and temperature range apparently. A single letter usually A-E, indicates a performance specification such as Vcc voltage range. That's also described as "industrial grade" or "commercial grade". Two letters indicate a performance specification followed by the package designation. Three letters, I'll have to work on that. The package-letter D is ceramic, E is plastic, H is a flat-pack; K is an unpackaged "die" (plural dice). See the reference notes below. - Herb

RCA date codes

A "date" code is some combination of letters and numbers to mark parts by week and year of production. The purpose of such marks, is to identify "lots" (production batches) for quality control. Translation: to catch any "oops" in production for recall or replacement.

After discussion among several owners and buyers of COSMAC 1802's, a reasonable conclusion is that RCA did not use consistent methods to date-code their COSMAC 1802's and other COSMAC chips. Generally, one or two digits represented the year (ignoring 19 or 20) and two digits represented week (00-53). Sometimes a single alpha letter followed. One must infer the correct decade, for single-digit year marks. - Herb Johnson

Single-letter marks after datecode or "RCA"

Ian May et al, identified RCA brand markings in discussion in cosmacelf Yahoo, April 2018. He identifed single letters R X Z K or (none). - Herb

"Along with the letter "R" I have 1802s with "X" and "Z". The white ceramic devices I linked to previously have the letter "K". I wondered if these perhaps designated different mask revisions. Early Harris devices that I have continue using the RCA 3 number code and the "Z". I then thought to look at other CDP1800 series devices that I have and found 1806s (Harris), 1851s, 1852s and 1854s (all RCA) with the letter "Z". So I don't think the letters have anything to do with the 1802 mask version. I also have devices without a letter, the 1802(027) that came with my VIP, some 1855s (also 027) and one 1854AEX(150). So the significance of "K","R","X" and "Z" remains unknown to me. It could be which factory or production line for example." - Ian May, April 2018

Embedded marks in mold pin-eject indentations

[1802 eject pin marks]

Ian May, identified RCA plastic package eject-pin molded markings. From discussion in cosmacelf Yahoo, April 2018. The example Ian discusses is from the project A copy of that image is referenced here on this Web page. - Herb

"Place the chip with the text the correct way up which should put pin 1 to the left. The [circular] mold eject pin mark is at the pin 20 end of the chip. [There's also a mold pin mark near pin 1 to the right.] I'm using a 10x magnifying glass for this. What I have noticed is that there is some information coded in the mold eject pin marks of most "R" chips, most "X" chips, some "Z" chips and "letter-less" ("NL") chips.

"If you look at the mold eject pin mark near the end of pin 20, you will find either a "^" or a ">". [Chips bought decades ago] that I have are marked "^" (2x1802(137) "R", 1x1802(027) "NL", 3x1855(027) "NL"). The 1802 [chips bought from new-old-stock in the USA] are "X" and the pin 20 end mark is ">". This looks to be a different font from the "^" marks on these chips.

"The pin 1 end mark holds even more information. For [chips bought decades ago] the (027) 1802 has ">" and 3 dots, two right of the ">" and one left of it. The (137) 1802 has 2 dots, one above the ">" and one left and below. The (027) 1855s have 4 dots, two left, one above and one right.

"The 1802 [chips bought from new-old-stock in the USA] "X" have "^" at the left end and 2 dots. I have one chip (150) 1854AEX "NL" with "^" and 3 dots at the left end. I have two [new-old stock] (510) 1854ACE "Z"s, one has ">" and 2 dots LHS and the other has no mold ejection marks at all. I have three [new-old-stock] (523) 1802s, one (610) and one (706) that are all "Z"s with no eject marks.

"For 1802 [chips bought used from the Far East that may be remarked] I have one (432) with marks and one without, both are "X"s. I have one similar-sourced (214) 1802 "NL" that has 3 dots and "^" at the left end and 4 "X"s the same as the [new-old-stock] "X"s ." - Ian May

Markings under the chip

On the underside of the COSMAC CDP1800-series chips, are a number of printed letters and numbers. As of April 2018 discussion, details of these are not readily identified. They may include country of packaging - "Phillipines". They may include a week/year code. there's other lettering. It's likely these are batch-production designations. It may take a lot of reporting, to make determinations about these markings. Ian commented about them, in a private email as below.

Ian: I have quite a few that have the underside markings scratched out (just the area where the markings were). It looks amateurish and is a dead give away that what's on the top has been altered. I have not seen any attempt to refinish the bottom surface as per the [remarked] top surface, so they either can't be bothered or their re-marking equipment can't handle the bottom (or I haven't seen enough fakes). The underside marks are not unique (I have a couple of pairs), so they do not identify individual chips. They also seem to be changing faster than the 3 digit codes on the top, which might mean that they identify wafers but this is pure speculation on my part.

Examples [chips bought from new-old-stock in the USA] 4 chips topside all the same: 1st line "CDP1802AE" 2nd line "RCA X" 3rd line "427". Underside 1st line (all the same) "6FVGH" 2nd line 1x"E8738", 1x"E8757" and 2x "E8673". Three more [chips bought from new-old-stock in the USA]: 1st line "CDP1802AE" 2nd line "RCA Z" 3rd line "523" underside 1x "6FVSO" "P4756" 1x "6FVSO" "Q4506" 1x "6FVTO" "S5083". With enough underside markings it might be possible to attach a 3 digit top side code for chips that have had the topside re-marked but still have original underside marking. - Cheers, Ian.

Documentation on production marks

DATABOOK series, "RCA Solid State - COS/MOS Memories, Microprocessors, and Support Systems", printed 8/79

Package and ordering information, page 5

D suffix, Dual-in-line Size-Brazed ceramic packages (gold/ purple?)
D suffix, Dual-in-line welded-Seal Ceramic packages (white/gold)
E suffix, Plastic Dual-in-line packages
K suffix. 24-lead Ceramic Flat Pack 
H suffix. chip (die)

CDP1800-Series IC products, CDP1802, CDP1802C, page 17

CDP1802 recommended operating range 4-10.5V
CDP1802C recommended operating range 4-6.5V
CDP1802D, CD operating temp -55C +125C
CDP1802D, CE operating temp -40C +85C

Copyright © 2018 Herb Johnson, except for extensive quotes produced by others

Herb Johnson
New Jersey, USA
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