[Simh] Old school programming with wiresnips and a question about debugging standalone assembly

[Johnny Billquist]

On 2015-12-17 00:51, Will Senn wrote:
> All,
>
> I was watching an old PDP-11 video when, seriously, I came across an
> explanation of programming that involved wire snips. It was interesting
> and brought home to me the concept of memory pages and such. I thought I
> would share the screen shot with y'all. If it doesn't come through
> imagine a guy with a pair of wire cutters snipping off diodes from a ROM
> card for a PDP11. Is this really how y'all programmed back in the day :)?

Not really. Diode roms would be usable for bootstraps, but not much 
else. And you normally programmed them once, and then you just had them 
there for years to come. Really short snippet of code that's read only. 
Same idea as any other ROM.

Not sure how you would see any connection between this and memory pages.

For programming, you normally have RAM (or CORE), and an operating 
system with various tools, such as editors, compilers, linkers and so on...

If you telnet to magica.update.uu.se, you'll be connecting to a real 
PDP-11/70 that is online. That's a machine from 1975. Now, it's running 
RSX-11M-PLUS V4.6, which is from 1999, but the original version of 
RSX-11M is from 1972 or so, so you'll get a good idea how programming 
was done "back then" by checking there. But it's not that exciting, 
really. It's pretty much the same as today.

> Is it possible to single step through a machine language program (such
> as the bootstrap loader) that was entered using deposit commands as it
> loads another program (such as the absolute loader,
> which this particular diode ROM represents) and similarly step through
> the absolute loader itself as it loads something like DEC-BASIC from
> paper tape, and if so, what does that process look like in SimH terms?

This is just plain memory like any other. Of course you can single step 
through it.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol