26 Oct
2018
26 Oct
'18
6:56 p.m.
From: Rob Jarratt
The chips where I believe the RESET is oscillating on
pin 23 have been
labelled E151 and E152 ... But I am not really sure if I have
identified them and the pin correctly.
E151 is the main CPU chip:
http://gunkies.org/wiki/F-11_chip_set
E152 is the KEF11-A floating point chip, and E150 is the KTF11-A memory
management chip.
Pin 1 of E150 is definitely in the lower left corner (in the photo); there's
an indent on the left-hand side of the chip, for the usual DIP orientation.
I'm pretty sure the other two have the same orientation.
Noel
27 Oct
27 Oct
1:06 a.m.
Thanks Noel. According to the printset for the KDF11-A pin 23 is the RESET
signal, which would make it the 3rd pin from the right at the top right of
the CPU. The printset also showed a second chip with its RESET on pin 23 and
I have confirmed that E151 and E152 have pin 23 tied together. So I am
pretty confident that this is indeed the RESET.
I have been tracing the source of the RESET, because as I have said it is
oscillating, and it seems to go through a *lot* of logic, and I haven't
fully traced the source of the oscillation yet.
Regards
Rob
there's
an
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Noel
Chiappa via cctalk
Sent: 27 October 2018 02:56
To: cctalk at classiccmp.org
Cc: jnc at mercury.lcs.mit.edu
Subject: Re: PinOut of DEC F11 Chips in a Professional 350
been
From: Rob Jarratt
> The chips where I believe the RESET is oscillating on pin 23 have labelled E151
and E152 ... But I am not really sure if I have
identified them and the pin correctly.
E151 is the main CPU chip:
http://gunkies.org/wiki/F-11_chip_set
E152 is the KEF11-A floating point chip, and E150 is the KTF11-A memory
management chip.
Pin 1 of E150 is definitely in the lower left corner (in the photo); indent on the left-hand side of the chip, for the
usual DIP orientation.
I'm pretty sure the other two have the same orientation.
Noel
5:47 a.m.
On Sat, Oct 27, 2018, 04:06 Rob Jarratt via cctalk <cctalk at classiccmp.org wrote:
I have been tracing the source of the RESET, because as I have said it is
oscillating, and it seems to go through a *lot* of logic, and I haven't
fully traced the source of the oscillation yet.
Have you checked the PSU output? My first guess would be bad caps in the
power supply.
Pat
9:22 a.m.
-----Original Message-----
From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Patrick
Finnegan via cctalk
Sent: 27 October 2018 13:48
To: General Discussion: On-Topic and Off-Topic Posts
<cctalk at classiccmp.org>
Subject: Re: PinOut of DEC F11 Chips in a Professional 350
On Sat, Oct 27, 2018, 04:06 Rob Jarratt via cctalk <cctalk at classiccmp.org>
wrote:
I should have said that I have already checked, the ripple is about 100mv peak to peak,
which I assume is OK. The green DC OK LED is illuminating too, so I think the PSU is
fine.
Regards
Rob
I have been tracing the source of the RESET, because as I have said it
is oscillating, and it seems to go through a *lot* of logic, and I
haven't fully traced the source of the oscillation yet.
Have you checked the PSU output? My first guess would be bad caps in the
power supply.
2247
days inactive
2247
days old
3 comments
3 participants
participants (3)
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jnc＠mercury.lcs.mit.edu -
pat＠vax11.net -
robert.jarratt＠ntlworld.com