Altair parts substitutions

From: Eric Smith <eric_at_brouhaha.com>
Date: Wed May 24 21:03:30 2000

I wrote:
> Intel's 5V 1K*8 part was the 2758. Other posts have claimed that an Intel
> 2758 is a half-bad 2716, but my fuzzy recollection from that era was that
> the ones I looked at had substantially different die sizes. For half-bad
> parts Intel usually added a suffix to the part number to denote which half
> was bad, and I didn't see such a designation on any of the 2758s I used.

Checking the 1980 Component Data Catalog reveals that those who claimed
that 2758 was a half-good 2716 are almost certainly correct. The electrical
specifications match the standard speed-grade (no suffix) 2716. Pin 19,
which is A10 on a 2716, is called "Ar" on a 2758, and is specified in the
DC and Operating Characteristics table as an input which should be in the
range of -0.1 to 0.8 V (i.e., logic 0). However, footnote 4 of that table
states:

    Ar is a reference voltage level which requires an input current
    of only 10 uA. The 2758 S1865 is also available which has a
    reference voltage level of Vih instead of Vil.

Essentially the same information is restated in the paragraph "Device
Operation".

It's very interesting how carefully they avoided making any statements
that pin 19 is an address line, instead calling it a reference voltage.
Received on Wed May 24 2000 - 21:03:30 BST