The Sinclair QL Forum

Nasta wrote: I think there was a flash version of the same PIC chip but has also been obsoleted, though one might still find some for sale.

Not to my knowledge. There are similar later ones that have flash memory, but I guess the subtile differences between versions will make them non-usable as a drop-in replacement. The 17C41 range did support external EPROMs, but at the loss of GPIO lines, so, no dice.

Pr0f wrote:looks like document AN726 covers migration from pic17cxxx to pic18cxxx - but sadly can't find a copy of this on Microchip site anymore.

The pic18 range are flash based with 100 year retention, and would not require too much code tweaking to port across from the 17C42 device.

The problem is of course the source code...

No luck as a drop-in replacement either. None of the 18Fxxx can be had in a PLCC form factor. But in case anybody is interested, the application note can be found here

Found this baby on RS components:

https://ly.rsdelivers.com/product/micro ... 44/1784856


No idea on pin compatibility - will have to check over the weekend

Morning. I just checked and yes it is indeed a PIC17C42 that does the job of the 8049. Everything around the part is normal. It has power and clock. It would go through several cycles and then just enter a repeating loop.

I wonder if Tony Firshman could be persuaded to release the PIC source?

pr0f wrote:looks like document AN726 covers migration from pic17cxxx to pic18cxxx - but sadly can't find a copy of this on Microchip site anymore.

This one: http://www.t-es-t.hu/download/microchip/an726a.pdf
Cheers,
Norm.

Hi

The key point here is the availability of the Superhermes ROM code.

I have asked a few times if the rom code was available to try and make SER3 with Sernet. But nothing ever came of the request.

I doubt Tony has the source to the Superhermes rom.

Well, I tested continuity from all the pins to the PIC or the 74238 according to the schematic and they are all fine. Measured the oscillator with a scope and it produces the correct clock but it's a wee bit unstable. Statistics on the scope showed std dev of 17kHz on the approx 14.5MHz clock. Not sure if that will disrupt proper operation of the PIC but I would assume not. I have seen uControllers work on a much dodgier clock.

Proceeded to hook up the logic analyzer to the PIC pins. I was watching the CTL and DATA signals between 8302 and the PIC. On boot 8302 pulls CTL low and waits for an ack on the DATA line. The CTL signal is received at the PIC but it does not respond. Verified with the standard IPC and saw CTL/DATA exchange as it *should* look like.

Also verified that there is no activity on the keyboard matrix scan lines. Those should be constantly polled by the PIC to look for keypresses. Nothing there.

My conclusion is that the PIC is dead.

Derek_Stewart wrote:I can ask Tony if he can supply me with the code and how to ipdate the flash rom.

Derek, I must now ask for this favour, can you please ask Tony if he has replacement PICs available or if there's a way to burn the code to a new one if I can find one? Please send me a PM if there's a way to do this and the cost involved. Thank you so much!

Cheers,
Petri