> For example, one problem I am looking for a solution is trying to read old
> single CHIP CPUs such as the Signetics/Philips MAB84XX series of chips. I know
> the ROM is embedded in the chip and can't normally be gotten at, I'm thinking
> thought that there is a rare document floating around that would show how to
> verify the ROM/RAM code by sending some signal in the T (est) pin-Input pin,
Are you sure that's not the T(imer) I/O pin?
> testable using the JT1 or JNT1 instructions, whatever those are! Not covered in
> any documents I've found so far though. I've found these so far which aren't bad:
Some old devices allow "program verify" to be performed from the pins
(e.g., the venerable 8048, et al.). These will gladly "dump" their
contents if asked to do so. (you have to be careful about what bit of
kit you *expect* to be able to do this; some will gladly toast the part
for you!)
Other devices were (are!) designed with the intent to make this "impossible".
(AFAICT, all have failed -- but in different ways!).
There are firms that will do this for you -- for a fee, of course.
Or, a precocious university student. Aside from devices that were
designed with the INTENDED ability to dump their contents, most
others require a fair bit of "hacking" (i.e., thus, a financial
incentive). Folks who do it "professionally", develop a "book of
tricks" for different devices, attack vectors, etc.
[I was actively involved in such Red/Blue team efforts years ago.
It's an interesting mindset. And, worthwhile skills developed to
help *protect* designs. But, on the whole, trying to copy other
designs is *so* uninteresting when contrasted with creating new...]
It's usually a lot easier (for small processors/applications) to just
reimplement the functionality in whatever device you choose. But,
that's not cheap, either (the advantage being you now have a design
that YOU own and can augment -- so "yours" is better than the original!)
Reply by bitrex●November 27, 20212021-11-27
On 11/27/2021 8:14 AM, Anthony William Sloman wrote:
> On Thursday, November 25, 2021 at 2:52:29 PM UTC+11, Anthony William Sloman wrote:
>> On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:
>>> On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
>>>> On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
>>>>> On 11/23/2021 5:44 PM, John Larkin wrote:
>>>>>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com>
>>>>>> wrote:
>>>>
>>>> <snipped the .asc file>
>>>>
>>>> https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf
>>>>
>>>> says that the transistor can't take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn't be that difficult to protect the junction, but it's not a great example of careful design.
>>>>
>>> Eh? There's no BJTs in that circuit my good man, at least there
>>> shouldn't be. You sure you responding to the right circuit?
>> I thought I'd picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn't seem to be a Q1 or a 2SCR552 in your text.
>>
>> A second attempt didn't go well, so I've got to say, oops - sorry. I'm not quite sure how I got it wrong and it may take me a while to find out.
>
> A third attempt went better. The circuit looks much more like what you were describing. It isn't obvious what it is supposed to do.
>
> I had to move a couple of resistors a bit to make them them sit on the wires that were obviously intended to connect them
>
> Vout+ sits at about 73V for about 13usec then drops to about -1V for about 1 usec. Vout- sits about -56V for the same 13usec and drops to -130V for the same 1usec.
>
> Is this what you intended? What was the intended application?
>
> Bill Sloman, Sydney
>
Measure across the terminals, the output is floating wrt ground.
Reply by Anthony William Sloman●November 27, 20212021-11-27
On Thursday, November 25, 2021 at 2:52:29 PM UTC+11, Anthony William Sloman wrote:
> On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:
> > On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
> > > On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
> > >> On 11/23/2021 5:44 PM, John Larkin wrote:
> > >>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com>
> > >>> wrote:
> > >
> > > <snipped the .asc file>
> > >
> > > https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf
> > >
> > > says that the transistor can't take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn't be that difficult to protect the junction, but it's not a great example of careful design.
> > >
> > Eh? There's no BJTs in that circuit my good man, at least there
> > shouldn't be. You sure you responding to the right circuit?
> I thought I'd picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn't seem to be a Q1 or a 2SCR552 in your text.
>
> A second attempt didn't go well, so I've got to say, oops - sorry. I'm not quite sure how I got it wrong and it may take me a while to find out.
A third attempt went better. The circuit looks much more like what you were describing. It isn't obvious what it is supposed to do.
I had to move a couple of resistors a bit to make them them sit on the wires that were obviously intended to connect them
Vout+ sits at about 73V for about 13usec then drops to about -1V for about 1 usec. Vout- sits about -56V for the same 13usec and drops to -130V for the same 1usec.
Is this what you intended? What was the intended application?
Bill Sloman, Sydney
Reply by Rich S●November 26, 20212021-11-26
On Thursday, November 25, 2021 at 8:48:03 AM UTC, Tom Del Rosso wrote:
> John Larkin wrote:
> > On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
> > <richsuli...@gmail.com> wrote:
> >
> >> the topic is "off topic"
> >>
> >> why do we have so many off-topic
> >> topics in this group?
> >>
> >> can we get on topic, and save the
> >> off-topic stuff in another group?
> >>
> >> = RS
> >
> > Not many people actually do electronic design, and the ones who do are
> > reluctant to show what they are doing in any detail.
> The majority of threads are on-topic, but they usually don't require
> many posts to solve the issue.
>
>
> --
> Defund the Thought Police
Indeed, Tom, probably often correct.
The on topic threads are resolvable (not so subjective,
not generally inflammatory).
It seems /some/ of us revel in the knee-jerk emotional
responses, jabe your fellow s-e-d poster, pulling people's
chain, stoking the fires, etc.
I never suggested we could ban all things off-topic.
I just wanted us to pause & think about it, at least.
And, it's good; I see some good points.
Maybe this group is mis-named. The world of
electronic engineering is more than "design".
Maybe the amount of design posted here really
reflects reality? --there isn't That Much new design work
taking place? Most things are re-hashes of standard
designs?
This audience is doing many other things
aside from pure design work. Still electronic-related.
And challenging.
thanks = RS
Reply by Tom Del Rosso●November 25, 20212021-11-25
John Larkin wrote:
> On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
> <richsulinengineer@gmail.com> wrote:
>
>> the topic is "off topic"
>>
>> why do we have so many off-topic
>> topics in this group?
>>
>> can we get on topic, and save the
>> off-topic stuff in another group?
>>
>> = RS
>
> Not many people actually do electronic design, and the ones who do are
> reluctant to show what they are doing in any detail.
The majority of threads are on-topic, but they usually don't require
many posts to solve the issue.
--
Defund the Thought Police
Reply by Anthony William Sloman●November 24, 20212021-11-24
On Thursday, November 25, 2021 at 1:23:06 AM UTC+11, bitrex wrote:
> On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
> > On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
> >> On 11/23/2021 5:44 PM, John Larkin wrote:
> >>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com>
> >>> wrote:
> >
> > <snipped the .asc file>
> >
> > https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf
> >
> > says that the transistor can't take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn't be that difficult to protect the junction, but it's not a great example of careful design.
> >
> Eh? There's no BJTs in that circuit my good man, at least there
> shouldn't be. You sure you responding to the right circuit?
I thought I'd picked it out of this thread, but the route through Notepad to the .asc file seems to have gotten messed up. There doesn't seem to be a Q1 or a 2SCR552 in your text.
A second attempt didn't go well, so I've got to say, oops - sorry. I'm not quite sure how I got it wrong and it may take me a while to find out.
--
Bill Sloman, Sydney
Reply by bitrex●November 24, 20212021-11-24
On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
> On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
>> On 11/23/2021 5:44 PM, John Larkin wrote:
>>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com>
>>> wrote:
>
> <snipped the .asc file>
>
> https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf
>
> says that the transistor can't take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn't be that difficult to protect the junction, but it's not a great example of careful design.
>
On 11/24/2021 1:18 AM, Anthony William Sloman wrote:
> On Wednesday, November 24, 2021 at 11:55:51 AM UTC+11, bitrex wrote:
>> On 11/23/2021 5:44 PM, John Larkin wrote:
>>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <sp...@flippers.com>
>>> wrote:
>
> <snipped the .asc file>
>
> https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/2scr552pt100-e.pdf
>
> says that the transistor can't take more than 6V of reverse bias. Your circuit simulates up to -18V across the base-emiter junction, only for about 15nsec, but probably long enough to get it avalanching in real life. It shouldn't be that difficult to protect the junction, but it's not a great example of careful design.
>
Eh? There's no BJTs in that circuit my good man, at least there
shouldn't be. You sure you responding to the right circuit?
Reply by Jan Panteltje●November 24, 20212021-11-24
On a sunny day (Tue, 23 Nov 2021 16:11:13 -0800) it happened John Robertson
<spam@flippers.com> wrote in <kYOdnS1cYIW_HgD8nZ2dnUU7-eXNnZ2d@giganews.com>:
>
>On 2021/11/23 2:44 p.m., John Larkin wrote:
>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com>
>> wrote:
>>
>>>
>>> On 2021/11/23 12:15 p.m., John Larkin wrote:
>>>> On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
>>>> <richsulinengineer@gmail.com> wrote:
>>>>
>>>>> the topic is "off topic"
>>>>>
>>>>> why do we have so many off-topic
>>>>> topics in this group?
>>>>>
>>>>> can we get on topic, and save the
>>>>> off-topic stuff in another group?
>>>>>
>>>>> = RS
>>>>
>>>> Not many people actually do electronic design, and the ones who do are
>>>> reluctant to show what they are doing in any detail.
>>>>
>>>
>>> So they feed the lunatic fringe instead?
>>>
>>> The trolls are killing interest in this group, and the group is helping
>>> them by responding to - The Marching Morons.
>>>
>>> John :-#(#
>>
>> OK, post some interesting electronics, preferably something specific.
>> A few real EEs show up here occasionally and might have something
>> intelligent to say.
>>
>> But yes, the less on-topic and the more stupid the thread, the longer
>> it is.
>>
>
>I don't do what most of you folks consider that interesting electronics.
>Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.
>I design a few boards, have a friend or two make others that are deeper
>in FPGA than I can go (no time or skill), but I try to have some fun
>with it all.
>
>For example, one problem I am looking for a solution is trying to read
>old single CHIP CPUs such as the Signetics/Philips MAB84XX series of
>chips. I know the ROM is embedded in the chip and can't normally be
>gotten at, I'm thinking thought that there is a rare document floating
>around that would show how to verify the ROM/RAM code by sending some
>signal in the T (est) pin-Input pin, testable using the JT1 or JNT1
>instructions, whatever those are! Not covered in any documents I've
>found so far though. I've found these so far which aren't bad:
>
>https://www.flippers.com/pdfs/MAB84XX_Signetics.pdf
>
>https://www.flippers.com/pdfs/MAB84X1_MAF84X1_MAF84AX1_Family.pdf
>
>Other 8-bit MPUs had such tests so you could cycle the data out to make
>sure the chip is good, why not this one?
>
>Like I say, fun, but not very modern tech...
>
>John :-#)#
In the long ago days there was much in hacker grousp like alt.satellite.tv.europe
I think it was, about hacking smartcards (especially with PIC micros)
Power supply variations and other tricks to make it list ROM / FLASH content etc.
Many papers were on the internet from very high tech like opening the chip
and probing the SillyCon to relative simple solutions.
I admit to playing with it :-)
Not sure how much is preserved, google.
Reply by Jan Panteltje●November 24, 20212021-11-24
On a sunny day (Tue, 23 Nov 2021 16:11:13 -0800) it happened John Robertson
<spam@flippers.com> wrote in <kYOdnS1cYIW_HgD8nZ2dnUU7-eXNnZ2d@giganews.com>:
>
>On 2021/11/23 2:44 p.m., John Larkin wrote:
>> On Tue, 23 Nov 2021 14:17:01 -0800, John Robertson <spam@flippers.com>
>> wrote:
>>
>>>
>>> On 2021/11/23 12:15 p.m., John Larkin wrote:
>>>> On Tue, 23 Nov 2021 11:58:55 -0800 (PST), Rich S
>>>> <richsulinengineer@gmail.com> wrote:
>>>>
>>>>> the topic is "off topic"
>>>>>
>>>>> why do we have so many off-topic
>>>>> topics in this group?
>>>>>
>>>>> can we get on topic, and save the
>>>>> off-topic stuff in another group?
>>>>>
>>>>> = RS
>>>>
>>>> Not many people actually do electronic design, and the ones who do are
>>>> reluctant to show what they are doing in any detail.
>>>>
>>>
>>> So they feed the lunatic fringe instead?
>>>
>>> The trolls are killing interest in this group, and the group is helping
>>> them by responding to - The Marching Morons.
>>>
>>> John :-#(#
>>
>> OK, post some interesting electronics, preferably something specific.
>> A few real EEs show up here occasionally and might have something
>> intelligent to say.
>>
>> But yes, the less on-topic and the more stupid the thread, the longer
>> it is.
>>
>
>I don't do what most of you folks consider that interesting electronics.
>Most of my work is trying to save obsolete games using 1970s 8-bit CPUs.
>I design a few boards, have a friend or two make others that are deeper
>in FPGA than I can go (no time or skill), but I try to have some fun
>with it all.
>
>For example, one problem I am looking for a solution is trying to read
>old single CHIP CPUs such as the Signetics/Philips MAB84XX series of
>chips. I know the ROM is embedded in the chip and can't normally be
>gotten at, I'm thinking thought that there is a rare document floating
>around that would show how to verify the ROM/RAM code by sending some
>signal in the T (est) pin-Input pin, testable using the JT1 or JNT1
>instructions, whatever those are! Not covered in any documents I've
>found so far though. I've found these so far which aren't bad:
>
>https://www.flippers.com/pdfs/MAB84XX_Signetics.pdf
>
>https://www.flippers.com/pdfs/MAB84X1_MAF84X1_MAF84AX1_Family.pdf
>
>Other 8-bit MPUs had such tests so you could cycle the data out to make
>sure the chip is good, why not this one?
>
>Like I say, fun, but not very modern tech...
>
>John :-#)#
In the long ago days there was much in hacker grousp like alt.satellite.tv.europe
I think it was, about hacking smartcards (especially with PIC micros)
Power supply variations and other tricks to make it list ROM / FLASH content etc.
Many papers were on the internet from very high tech like opening the chip
and probing the SillyCon to relative simple solutions.
I admit to playing with it :-)
Not sure how much is preserved, google.