5 ms·

Here you can read the source code of first edition unix: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1 https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1 Whe

by smlckz 6y ago

Here you can read the source code of first edition unix: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1 https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1 Where can we learn the PDP assembly to be able to understand these historical source code?

kencausey 6y ago
https://en.wikipedia.org/wiki/MACRO-11 https://en.wikipedia.org/wiki/MACRO-11 and linked from that page http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/RSX11M_V2/DEC-11-OIMRA-A-D_MACRO_75.pdf http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/RSX11... There are probably better references, but that's what I found in a quick look.
segfaultbuserr 6y ago
Read the official manual - PDP-11/40 Processor Handbook. https://pdos.csail.mit.edu/6.828/2005/readings/pdp11-40.pdf https://pdos.csail.mit.edu/6.828/2005/readings/pdp11-40.pdf The PDP-11 instruction set is small and elegant.
- Shared404 6y ago
  From the manual: > The PDP-11/40 was designed to fit a broad range of applications, from small stand alone situations ... to large multi-user, multi-task applications requiring up to 124K of addressable memory space. I'm young, and it's crazy to look back and see how far we've come.
  - tyingq 6y ago
    For some context, the PDP-11/40 debuted in 1973, and was $40k in 1973 dollars which is $233k inflation adjusted for today. There wasn't much available for a "home computer" at the time, but the Kenbak-1 might be a good example for comparison of what one would have cost. It was $750, or $4400 inflation adjusted. It had 256 bytes of memory.
- gjvnq 6y ago
  > The PDP-11 instruction set is small and elegant. Scared PDP-endianess sounds...
  - freeone3000 6y ago
    It's little-endian, same as x86.
    - tomatocracy 6y ago
      I thought on the PDP-11 bytes in a 16 bit word were stored little endian but the 16 bit words in a 32 bit long were stored the other way around so it's a bit of both?
      - userbinator 6y ago
        Words are little-endian but the two halves of a long are big-endian. In consistently little-endian, a 32-bit quantity would be stored with the 1's, 256's, 65536's, and 16777216's place bytes in that order, but the PDP-11 puts them in the order 65536 16777216 1 256.
  - deleted 6y ago
    [deleted]
em500 6y ago
And here's a (big!) project that aims to reconstruct a complete source history from the current FreeBSD all the way back to 1970 Unix. https://github.com/dspinellis/unix-history-repo https://github.com/dspinellis/unix-history-repo

by smlckz 6y ago

kencausey 6y ago

https://en.wikipedia.org/wiki/MACRO-11 https://en.wikipedia.org/wiki/MACRO-11 and linked from that page http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/RSX11M_V2/DEC-11-OIMRA-A-D_MACRO_75.pdf http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/RSX11... There are probably better references, but that's what I found in a quick look.

segfaultbuserr 6y ago

Read the official manual - PDP-11/40 Processor Handbook. https://pdos.csail.mit.edu/6.828/2005/readings/pdp11-40.pdf https://pdos.csail.mit.edu/6.828/2005/readings/pdp11-40.pdf The PDP-11 instruction set is small and elegant.

Shared404 6y ago
From the manual: > The PDP-11/40 was designed to fit a broad range of applications, from small stand alone situations ... to large multi-user, multi-task applications requiring up to 124K of addressable memory space. I'm young, and it's crazy to look back and see how far we've come.
- tyingq 6y ago
  For some context, the PDP-11/40 debuted in 1973, and was $40k in 1973 dollars which is $233k inflation adjusted for today. There wasn't much available for a "home computer" at the time, but the Kenbak-1 might be a good example for comparison of what one would have cost. It was $750, or $4400 inflation adjusted. It had 256 bytes of memory.
gjvnq 6y ago
> The PDP-11 instruction set is small and elegant. Scared PDP-endianess sounds...
- freeone3000 6y ago
  It's little-endian, same as x86.
  - tomatocracy 6y ago
    I thought on the PDP-11 bytes in a 16 bit word were stored little endian but the 16 bit words in a 32 bit long were stored the other way around so it's a bit of both?
    - userbinator 6y ago
      Words are little-endian but the two halves of a long are big-endian. In consistently little-endian, a 32-bit quantity would be stored with the 1's, 256's, 65536's, and 16777216's place bytes in that order, but the PDP-11 puts them in the order 65536 16777216 1 256.
- deleted 6y ago
  [deleted]

em500 6y ago

And here's a (big!) project that aims to reconstruct a complete source history from the current FreeBSD all the way back to 1970 Unix. https://github.com/dspinellis/unix-history-repo https://github.com/dspinellis/unix-history-repo