Hi all,
I'm looking for some info on the 2050. The parts list identifies the dsp as
a modified uPD7720 and gives its part number as 351-8869-020. The ICs are
labelled as 3518869020 so I assume the modification was to the die and was
modified NEC as a special for Collins?

Anyone know what the mods are and whether a stock 7720 can be used as a
replacement?

I was thinking about installing U14 for the ISB.

Otherwise, anyone have any of the DSP ICs 351-8869-020 available? or perhaps
a complete A3 board?

While I'm at it, anyone know what U15 is/was for?

Thanks
Greg

gcd. at. iimetro. dot. com. dot. au

gcd wrote:
Hi all,
I'm looking for some info on the 2050. The parts list identifies the dsp as
a modified uPD7720 and gives its part number as 351-8869-020. The ICs are
labelled as 3518869020 so I assume the modification was to the die and was
modified NEC as a special for Collins?

The uPD7720 is a mask-programmed microprocessor. There is firmware (both
data and program code) on ROM that is on the chip. It's not "modified,"
it's just got custom firmware on it.

Anyone know what the mods are and whether a stock 7720 can be used as a
replacement?

No, you cannot buy a "stock" 7720, you can only buy it with some random
software in it. Random software is not useful.

I was thinking about installing U14 for the ISB.

Otherwise, anyone have any of the DSP ICs 351-8869-020 available? or perhaps
a complete A3 board?

Rockwell-Collins _might_ be able to help you. Are you sure that the
microprocessor is bad?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Hi Scott,
I should pay more attention to the data sheet. Here I was thinking todays
DSP when I should have been thinking of 25 years back. You are correct, it's
a masked processor. Ah well that ruins that idea.

No faults - Just wanted to install an isb processor - I assummed the code
was in the eproms!!

Hmm.... wonder if the masked program code can be read out to modify the I &
Q processors etc

Thanks
Greg

"Scott Dorsey" wrote in message
...
gcd wrote:
Hi all,
I'm looking for some info on the 2050. The parts list identifies the dsp
as
a modified uPD7720 and gives its part number as 351-8869-020. The ICs are
labelled as 3518869020 so I assume the modification was to the die and was
modified NEC as a special for Collins?

The uPD7720 is a mask-programmed microprocessor. There is firmware (both
data and program code) on ROM that is on the chip. It's not "modified,"
it's just got custom firmware on it.

Anyone know what the mods are and whether a stock 7720 can be used as a
replacement?

No, you cannot buy a "stock" 7720, you can only buy it with some random
software in it. Random software is not useful.

I was thinking about installing U14 for the ISB.

Otherwise, anyone have any of the DSP ICs 351-8869-020 available? or
perhaps
a complete A3 board?

Rockwell-Collins _might_ be able to help you. Are you sure that the
microprocessor is bad?
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

gcd wrote:

Hmm.... wonder if the masked program code can be read out to modify the I &
Q processors etc

It's possible, there is a trick with the 8048 that allows you to force it
to output program rom (but not data rom) on output pins. There may be
something similar for the NEC. And it is still possible that someone at
Rockwell might be willing to provide a dump.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."