How to read code from P87C750?

Obsolete data controller from defunct company uses this Philips ucontroller.
Units are failing and customer has the option of either throwing out all his
infrastructure when these units fail and spending $$$$ to replace everything,
or burning new controller ICs as units fail.

It looks like the P87C750 comes with a 16-byte encryption table, optionally
used to encrypt the contents of program memory.
The only way, it seems, to know if the memory contents has been encrypted is
to read the contents and see if it contains legible code.
Is there another means to know if the memory contents have been encrypted?
Thanks.
Reply to
Gary Walters
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1K of code space is not much.
A logic analyzer and a few hours with a working unit and you will have replacement code ready to go.
How many of these units are we talking about ?
2-3 units a month, 2-3 units a year ??
As the company is now gone, what other type of products are in that market place ?
In this day and age, building a replacement is easier than fooling with encryption.
My $.02
hamilton
Reply to
hamilton
On a sunny day (Fri, 14 Dec 2012 12:22:31 -0800) it happened Gary Walters wrote in :
It should not be impossibe to crack if encrypted, even with all 7 bytes being not 0xff. The plaintext is asm instructions as machine code, it probably starts predictabe with jump, fast computer. I once wrote a 8052 assembler, this seems like a fun project for somebody who is into that sort of thing.
Reply to
Jan Panteltje
"The Philips 8XC750 offers the advantages of the 80C51 architecture..."
ADVANTAGES of the 8051 architecture???!!!
Reply to
John Larkin
I hope that's not the sound of The Segue I hear...
Reply to
Gary Walters
Well, it sure beat the heck out of the preceding MCS-48 architecture!
Reply to
Spehro Pefhany
How can I email you directly ?
hamilton
Reply to
hamilton
What was really the worst uP architecture? That RCA 17xx thing?
Reply to
John Larkin
The early PICs were about unusable for anything complex (ugly paging and no interrupts) and I wasted a bit of time trying. I never used the RCA thing. Maybe some of the 4-bit ones- they were pretty starved of gates.
Best regards, Spehro Pefhany
Reply to
Spehro Pefhany
The 68000. Too boring. ;-)
Reply to
krw
Think it was this one: RCA CDP1802
formatting link

The Galileo spacecraft used multiple 1802 microprocessors.
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The spacecraft was controlled by six RCA 1802 COSMAC microprocessor CPUs: four on the spun side and two on the despun side.
spun/despun ????
hamilton
Reply to
hamilton
The RCA 1802 was the champ for rad-hard applications such as spacecraft, for a long long time.
Cheers
Phil Hobbs
Reply to
Phil Hobbs
IIRC, they had a Silicon-on-Saphire version for rad-hard applications.
Best regards, Spehro Pefhany
Reply to
Spehro Pefhany
CMOS static cells. Really big CMOS static cells.
Reply to
krw
Hey, I love the 68K. Its assembly language is practically a higher-level language. The architecture is beautifully symmetric, sort of a 32-bit PDP-11.
It's big-endian and does a move from source to destination (unlike certain popular, barbaric architectures I could name.)
Reply to
John Larkin
Part of the spacecraft was spin stabilized, the other not (antennas and cameras hate that).
Spacecraft
"The spacecraft was constructed in three segments, which help focus on these areas: the atmospheric probe; a non-spinning section of the orbiter carrying cameras and other remote sensors; and the spinning main section of the orbiter spacecraft which includes the fields and particles instruments, designed to sense and measure the environment directly as the spacecraft flies through it. The spinning section also carries the main communications antenna, the propulsion module, flight computers and most support systems.
formatting link
Reply to
krw
When I was a new grad student, I spent one quarter working for Prof. Peter Banks (who was Sally Ride's advisor) at the STARlab at Stanford. He was a really good guy, doing interesting stuff, and hey, I thought, maybe I'll get to fly on a shuttle too. (This was in 1984, before Challenger.)
The day I decided to bail out and go back to building stuff on optical tables was the day he announced that he'd finally got approval to fly a mission he'd first proposed in _1968_. (It was the tethered satellite approach to electricity generation, the one that had the spectacular insulation failure on-orbit.)
Another one of his students spent 4 years building an instrument to fly as a 'getaway special' on a Delta, only to see it go into the Atlantic and have to get his degree by analyzing somebody's old data. :(
'Tis a bit of a heart-scald, this space business, as my grandmother might have said.
Cheers
Phil Hobbs
Reply to
Phil Hobbs
I still have the 1802 processor manual from my old cosmac Elf.
Cheers
Reply to
Martin Riddle
Ahhh. Good memories. I had a book about how to build a COSMICOS home-brew computer (a PCB with among other electronics a hex-keypad and some 7 segment displays) around a 1802. Never build the thing but I read the book several times just to learn about designing stuff around microprocessors.
Reply to
Nico Coesel
That sounds an entirely reasonable approach unless you can find someone from the defunct company. I know of a couple of products that were in relatively small-scale production using that series of CPUs unencrypted. Once they worked, they went straight into production. I'd assume it's unencrypted until you find anything to suggest otherwise.
Reply to
Martin Crossley

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