A very interesting port for an "OS-less" platform would be a port to the PIC

family of microcontrollers. There may be some issues because memory is in short

supply but notwithstanding, this would be pretty cool.

Any comments?

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Nick Brown wrote

A very interesting port for an “OS-less” platform would be a port to the PIC

There is a 8 bit, a 16 bit, and a 32 bit series of PIC processors. The 32 Bit platform is MIPS.

-Michael

In our previous episode, Nick Brown said:

A very interesting port for an "OS-less" platform would be a port to the PIC family of microcontrollers. There may be some issues because memory is in short supply but notwithstanding, this would be pretty cool.

As Michael said, what PIC exactly ? The three ranges (8/16/32) are totally different. I'm using the 8-bitters and the 16-bitters.

- IIRC the 8-bit PICs have a segmented memory model (pages of 256 bytes selected using a selector register)

- 2-8kb of memory (maximum on the 16-bit iirc, with maybe a 16kb coming soon) is too little to even use strings and other normal routines.

- You need SFR support, but worse, to convert the device specific header file for each of the hundreds of different chips, and maintain them.

IMHO, porting FPC to 8 and 16 Bit PIC is close to impossible, while a PIC 32 Bit (=MIPS) port should be doable.

-Michael

If it's really interesing, somebody would have started already a port.

In our previous episode, Florian Klaempfl said:

Afaik all architectures are done by three long time FPC devels (Jonas, Peter, Florian, correct me if I'm wrong), except for PPC64, so that is a bit oversimplified maybe?

If it really was that way, there would have been more variation in who made new ports.

... and except sparc (started by Mazen) and m68k (started by Carl). Both were not long time FPC developers when they started the port ;)

I'd really appreciate the 32 Bit PIC stuff, as this is MIPS and I might want to do a NIOS port some day and the NIOS ISA is said to be quite similar to MIPS (even the names are only a few bits apart :) )

-Michael

Op Thu, 23 Jul 2009, schreef Michael Schnell:

I'd really appreciate the 32 Bit PIC stuff, as this is MIPS and I might want to do a NIOS port some day and the NIOS ISA is said to be quite similar to MIPS (even the names are only a few bits apart :) )

The main challenge for a MIPS port is the absence of flags, there is a lot of code in the compiler that returns expression results in LOC_FLAGS. Of course it is perfectly possible to change these codes to use LOC_REGISTER, but it is work.

Daniël

I'd really appreciate the 32 Bit PIC stuff, as this is MIPS and I might want to do a NIOS port some day and the NIOS ISA is said to be quite similar to MIPS (even the names are only a few bits apart :) )

-Michael

The main challenge for a MIPS port is the absence of flags, there is a lot of code in the compiler that returns expression results in LOC_FLAGS. Of course it is perfectly possible to change these codes to use LOC_REGISTER, but it is work.

I see. Thanks for the pointers !

-Michael