8085 vs 8085A
cannings at earthlink.net
Tue Aug 7 03:11:07 CDT 2007
> I was looking through my collection yesterday and was testing out an old
> Intel SDK85 system. I noticed the main processor is stamped 8085, which
> means this chip is either an 8085 or the "A" was not printed properly and
> the chip is really an 8085A.
> I have a few 8085 systems and a box of 8085 CPUs. I checked them all and
> every one of them is an 8085A. I don't think I have ever seen an 8085,
> they've all been 8085A types.
> Other than the stamp on the chip, is there anyway I can tell the
> between an 8085 and an 8085A? Furthermore, is the 8085 rare, and I should
> put the chip away, or is it nothing special?
> Why did Intel bring out the 8085A? Were there issues with the 8085?
There were multiple versions of 8085 microprocessors. The original version
of the 8085 microprocessor without suffix "A" was manufactured by Intel
only, and was very quickly replaced with 8085A containing bug fixes. A few
years after that, around 1980, Intel introduced 8085AH - HMOS version of
8085A. There was also 80C85A - CMOS version of the 8085A. It's not clear if
80C85 was ever manufactured by Intel or not, but it was produced by at least
two second source manufacturers - OKI and Tundra Semiconductor. Tundra
Semiconductor manufactured the fastest 8085 microprocessor running at 8 MHz.
Second source manufacturers: AMD, Mitsubishi, NEC, OKI, Siemens, Toshiba.
Best regards, Steven C.
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