[yucafrita]

Havent found a discussion about it yet, so here it is. Just came to my mind...

Would it be possible to hack the firmware of a Pentax AF film SLR?

I will expand this... The AF film SLRs, Z-series or MZ-series, have pretty sure some sort of firmware and the possiblity of user settings. Obviously, there is no way we can update the firmware like for DSLRs. I dont know if there is a secret access for service engineers...

Now, this firmware is surely stored in a chip somewhere on the camera board. Probably it can be read out. Without documentation, it would have to be reverse-engineered. Then, if you edit the firmware, throw out the power zoom feature and add SDM/DC instead (the contacts are in the mount...), write this to an EPROM-like chip (if there's a fitting one) and install it on the board... Would be a nice add-on for modern AF lenses.

Too bad I am not a tech-head...

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Last edited by yucafrita; 08-29-2018 at 04:39 AM.

[victormeldrew]

There are two issues here that are unknown.

1) Is there a programmable chip in there with the program on-board, or is the programming handled by simple logic chips. Probably it is a microcontroller, so probably it is programmable in some way, but without seeing the circuit diagram I wouldn't be able to say.

2) If it IS programmable, has the circuit been designed for ICSP (In-Circuit Serial Programming) - it needs to be deliberately designed in. The answer here is almost certainly not...unless they intended the firmware to be updatable by the user or repair shops, there is no need to go to the expense. Seeing as the programming is fairly simple (and so can be thoroughly tested as bug-free) and there is no need to add new features, this is highly unlikely. And so the only option would be to remove the chip(s) from the board to gain access.

The short answer is: yes, anything is possible in theory, but whether it is practical is another matter.

[aaacb]

I also think that those cameras indeed have a microcontroller running code, I'd be surprised if even a super program didn't because something needs to drive the segment lcd dispay.
But I doubt the memory is programmable, afaik lots of embedded devices used to be shipped with code in a rom (and not some re-programmable memory), including video game cartridges.

[Wasp]

Disclaimer: I have never looked at the circuit diagram for any camera so I can only talk in general, but I have seen some electronics in my time.

The problem is that the film bodies did not have any provision for user updates like digital ones have. It is this ability that makes it possible to roll your own firmware.

It would certainly be possible to read the ROM from your film body, if you have the right equipment. The ROM chip that the code is stored in would probably be soldered to the board. Space is very tight inside a camera and a socket would just eat up real estate. If you do manage to read it, it will just be a lot of numbers. You would still have to reverse engineer that.

This assumes that there is a CPU to start with. Only AF bodies would have that but I don't know the details. Something older like an LX would be mostly analog. There might be some logic circuitry but that is a world away from computer code.

[victormeldrew]

All of this also relies on being able to engineer (reverse or otherwise) the SDM code. This also relies on the chip (if any) being capable of running the code (program space might be an issue - as might PWM capability).

Actually the easier way by far would be to outright replace the chip with a new one with your own program.

[yucafrita]

Yeah, I would think that one had to exchange the ROM chip with a new one. In the old computer days, there were sometimes piggy-back extensions (like turbo cards etc) but in a camera there just isnt enough space for that approach.

Oh well, so it's always screw-drive time...

[victormeldrew]

It would be an interesting project for someone with the kit, the expertise and the desire. It is far from an easy job though, so the desire would need to be strong. I think here that the benefit is far from the equal of the effort.

[yucafrita]

It would be an interesting project for someone with the kit, the expertise and the desire. It is far from an easy job though, so the desire would need to be strong. I think here that the benefit is far from the equal of the effort.

Maybe something for crowdfunding, but yes, too few people would be interested I guess. Plus, the different models would need each a separate effort. I doubt an MZ-S is too similar to a Z-series camera regarding the code.

[Wasp]

It is also possible the the code is inside the CPU chip itself. It would certainly save space and keep down cost. There was little need of any software updates on these old timers. Anything new would have been a normal production change.

All of the above assumes that it would be worthwhile to hack dad's film SLR. Me thinks that there is little or no new capability hidden in there that is not already available. Remember, there is no four way selector or screen with menus, only the buttons that Pentax (or any other maker) put there. In other words, how would any clever new features be accessed?

Finally, it is doubtful that Pentax left anything on the table as far as CPU power or hardware capabilities go. The camera business is/was just too competitive for that.

[Wasp]

It is also possible the the code is inside the CPU chip itself. It would certainly save space and keep down cost. There was little need of any software updates on these old timers. Anything new would have been a normal production change.

All of the above assumes that it would be worthwhile to hack dad's film SLR. Me thinks that there is little or no new capability hidden in there that is not already available. Remember, there is no four way selector or screen with menus, only the buttons that Pentax (or any other maker) put there. In other words, how would any clever new features be accessed?

Finally, it is doubtful that Pentax left anything on the table as far as CPU power or hardware capabilities go. The camera business is/was just too competitive for that.

[timw4mail]

It is also possible the the code is inside the CPU chip itself. It would certainly save space and keep down cost. There was little need of any software updates on these old timers. Anything new would have been a normal production change.

All of the above assumes that it would be worthwhile to hack dad's film SLR. Me thinks that there is little or no new capability hidden in there that is not already available. Remember, there is no four way selector or screen with menus, only the buttons that Pentax (or any other maker) put there. In other words, how would any clever new features be accessed?

Finally, it is doubtful that Pentax left anything on the table as far as CPU power or hardware capabilities go. The camera business is/was just too competitive for that.

Considering how little extra room there is on current cameras for firmware changes, I imagine there is virtually no room for modernity upgrades, if you can upgrade at all. It's quite possible that all or nearly all film SLRs used only hardware/ROM, and not firmware.

[sqrrl]

It is possible, but probably quite difficult.

If there is some form of in circuit programming you could theoretically reflash it - assuming that you can assess the datasheets, the coding platform, and the hardware too do this. Otherwise you could theoretically desolder the chip, build a test circuit and read the hex file (assuming you have all of the above), but then you would also need to go over the schematic and work out what registers were assigned to which parts of the circuit, decode the hex into assembly (once of course you understood the machine instructions), then work backwards until you understood it, before programming a new chip with a custom hex file of your own design and resoldering the circuit.

Actually, on second thoughts... It is probably possible, but also probably very very bloody difficult.

[leekil]

I thought I heard of a firmware update for the 645N or 645NII, but it seemed like a factory thing and not user-appliable. It could have been a chip replacement for that matter.

---------- Post added 08-29-18 at 01:18 PM ----------

Maybe "firmware update" was not the correct term.

[johnha]

It's a non-starter, it's likely to be a custom masked chip which can't be re-programmed, reproducing a 'similar' chip and getting it to work is going to be extremely difficult. It would be difficult enough to strip the camera down and rebuild it without breaking anything and keeping everything aligned as it should be.

[stevebrot]

It's a non-starter, it's likely to be a custom masked chip which can't be re-programmed, reproducing a 'similar' chip and getting it to work is going to be extremely difficult. It would be difficult enough to strip the camera down and rebuild it without breaking anything and keeping everything aligned as it should be.

What they said ^ ^ ^.

Basic camera functionality is actually pretty simple, even gee-whiz stuff like matrix metering and TTL/P-TTL flash can be handled by baked-in instructions. As for "secret access for service engineers", that takes the form swapping catalog parts.


Steve