Tech nostalgia enthusiasts have made a PiDP-10, a replica of the PDP-10

Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by Suzuran on Monday June 17, 2024 @08:41AM (#40705014)

The problem is that the PDP-10 is really unsuited to running C. It doesn't use 8-bit bytes and doesn't have a native "byte" datatype, just words and halfwords. There are byte instructions, but you have to construct a "byte pointer" to use them, which is a control word describing bytes of arbitrary size. The PDP-10 also has no single dedicated stack pointer, any AC except for the program counter can be used as a stack pointer, to its own independent stack if you want.

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Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by larsbrinkhoff on Monday June 17, 2024 @09:51AM (#40705624)

No dedicated stack pointer isn't much of a problem. Stack growing up might be.

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Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by Pet_Ant on Monday June 17, 2024 @10:50AM (#40706158)

Isn't stack direction an ABI convention rather than language or processor limit? I mean if you are trying to run existing PDP-10 binaries (I don't know of any that are publicly available), sure. But just to get to the point that you are running bash and serving and HTML Hello World from Apache, it shouldn't be an issue.

> 8-bit bytes

Doesn't the C standard just specify the minimum range of datatypes, and the max? Don't know if you can tell the size of actual bit without triggering UBI. (obviously not a C programmer)

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Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by Suzuran on Monday June 17, 2024 @11:11AM (#40706394)

The standard specifies that you must have an independently addressable unit of storage that corresponds to the basic character set. The PDP-10 does not have this.

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Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by Pet_Ant on Tuesday June 18, 2024 @04:02PM (#40721651)

Interesting. Found this story:

https://stackoverflow.com/a/8061758/254477

So, it has been ported to some weird platforms.

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Re:Tech nostalgia enthusiasts have made a PiDP-10, a replica... by Suzuran on Monday June 24, 2024 @08:44AM (#40775353)

Oh, there is/was a C compiler for the -10 (KCC), but it wouldn't support the modern dialects that the *BSD kernels are written in. Just having the language isn't enough, you have to be able to support the build chain of a modern kernel.

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