[Tack-devel] Bare metal PDP-11 developer toolchain

[Béla B. <bel...@gm...>]

Hello again,

I'm looking for a toolchain that would allow me to develop simple programs
in C for a PDP-11/05, which do not need the services of the operating
system. I found several sources on the net, where different solutions were
tried for this purpose, with more or less success. What I tried so far was
the GCC cross-compiler with PDP-11 a.out output, partly with the newlib C
library and some custom-implemented libc functions. I just made a very
simple "Hello Word" test program, for which I used my own crt0 startup file
and linker script. One problem is that PDP-11 support is no longer typical
in modern development environments, and another problem is that even the
theoretically small and simple newlib libc functions are very complicated
and result in large code, which is not good for me, because on my own
PDP-11/05 machine a total of 16kB of memory is available, but in the SIMH
emulator only a maximum of 56kB.
During my research I found ACK, which I liked in several ways. It is good
that it has the complete libc and I like it from the point of view that the
code is simple and readable and the code of libc and system functions can
be easily customized. I would of course make the UNIX function call stubs
so that the compiled program works without an operating system. But then
ACK itself can be easily compiled and run on a modern Linux. So far, for me
this is the most promising compiler to implement my idea.
However, there are a few problems that I don't know how to solve with ACK.
One is that it would be nice to have an assembly file output that shows the
specific memory addresses set by the linker alongside the instructions, and
the file also contains the assembly code of all external functions that the
program uses, just like in the gcc output .s files. The other is that since
there is no file system on the machine, instead of the a.out output, I
would actually only need a binary output file that starts at address 0. At
this address, there is only a jump instruction to the first instruction of
crt0.
How can I solve these with ACK?

Best regards,
Béla