[vcf-midatlantic] Can anyone identify this mystery IC

[Dave McGuire]

   I think those are actually six small groups of transistors, not six 
transistors.  Possibly inverters; these can be built in a CMOS chip with 
two transistors, which would usually be physically adjacent.

              -Dave

On 8/21/22 15:35, Douglas Crawford via vcf-midatlantic wrote:
> They are changing their tune, Dave :)
> 
> One says:
> " Metalization is hiding all the lower levels. Looks like a device with 
> just 6 transistors."
> Another responds:
> "So it would be a *transistor* array, not a gate array then.
> If so, then I’m confused as to why it would need so many pins if there 
> are only 6 transistors.  Unless it was a prototyping part where all the 
> transistors were individually made accessible."
> 
> (I'm positing with them # pins is because possibly they're gates)
> 
> 
> 
> 
> On 8/21/2022 12:50 PM, Dave McGuire via vcf-midatlantic wrote:
>>
>>    Yes, but we should be able to determine everything, or almost 
>> everything we need to know from that layer.  We'd need better and 
>> higher-resolution photos.
>>
>>               -Dave
>>
>> On 8/21/22 12:48, Douglas Crawford via vcf-midatlantic wrote:
>>> Ah, now we are getting somewhere.
>>> We can only guess then, from the remaining metalization layer
>>> correct?  Educated guess?
>>>
>>> On 8/21/2022 12:43 PM, Dave McGuire via vcf-midatlantic wrote:
>>>> On 8/21/22 12:39, Douglas Crawford via vcf-midatlantic wrote:
>>>>> These are the transistors?
>>>>> https://imgur.com/aLpqVpE
>>>>
>>>>    I'd need to look more closely, but those appear to be clusters of 
>>>> transistors, six of them.  They are likely gates.
>>>>
>>>>> I got one additional response from another designer:
>>>>> "Looks like some kind of gate array with only the metalization 
>>>>> layer being clearly visible. I worked on alot of these in the late 
>>>>> 70's. I have no explanation for the bonding pad structures."
>>>>
>>>>    Agreed; this has either had its passivation layer removed, or it 
>>>> had never been applied.  I suspect the latter, as it would've been 
>>>> removed with acid, and there isn't so much as a trace of debris from 
>>>> that.
>>>>
>>>>              -Dave
>>>>
>>
>>


-- 
Dave McGuire, AK4HZ
New Kensington, PA