National Semiconductor Mass Storage Handbook

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Tony,

Here is my list of what it isn't ;

Part Number   Pins   Match Function ?



DP8451           20      NO

DP8455           20      NO

DP8459           28      NO ( PCC )

DP8460           24      ???

DP8461           24      NO

DP8462           24      NO

DP8463           28      NO

DP8464           24      NO

DP8465           24      NO

DP8466           48      NO

DP8469           PCC  NO



Couldn't find any poop on the DP8460 ????



Best regards, Steven



> >
> > Hi Tony,
> >
> > Thanks Al for the heads-up on the datasheets !! Tony, do you think it is
>
> Indeed. That was extremely fast and very helpful. At least I know what it
> isn't..
>
> > some kind of  Manchester / Miller encoder / decoder ? Do we know if it
is a
>
> Yes. I think it's the circuit that combines and separates clocks and data
> pluses. Possibly RLL 2.7 code, I thought it might be a DP8463, but none
> of the signals match.
>
> > National chip or has it's total identity been wiped ? Maybe Signetics or
> > Plessey or TI or ?? Where are the power pins ( sometimes that is a good
>
> A proverb about grandmothers and sucking eggs springs to mind :-) :-)
>
> > tell ) ?   You mentioned 24 pin skinny DIP ? I'll keep looking. This is
for
> > some type of magnetic disk / floppy media system ?
>
> OK, more seriously, I'll tell you what I've discovered.
>
> This is a chip on the logic board of an HP winchester drive with what I
> am pretty sure is an ESDI interface. This board has about 50 chips on it,
> inclduing the 8053 microcontorller and a custom PGA thing with 95 pins.
>
> The chip in question has a National Semiconductor logo and the HP
> house-code 1820-5422. It's a 24 pin skinnyDIP (normal 0.1" pin spacing,
> 0.3" between the rows).
>
> As I said, I think the host interface on this drive is ESDI. The
> read/write data and read/write clock differential signals from the 20 pin
> connecotr are buffered in the ovious way (I forget the numbers of the
> buffer chips, but I have data sheets on them) and then go to this device.
>
> I;'ve not traced many pins yet, but the ones I know are :
>
> 8 : +5V (Vcc)
> 9 : Master clock input (from a 20MHz oscillator can)
> 11 : Write Clock input
> 12 : Write Data input
> 15 : Read Data output
> 16 : Read Clock output
> 20 : Ground
>
> There are no other pins connected to power or ground, which pretty much
> makes the ones I've found the real power pins (as opposed to, say, mode
> control pins that are tied high or low).  Thoes power pins are odd
> (not the corner pins).
>
> >
> > Pinouts are the same for the AMD 8051 / 8053. Hope that helps.
>
> Thanks.
>
> -tony