Anyone else have trouble getting LAS/OSR to work?

[Jeff Shrager]

I have been having a lot of fun w/my 8i. I mostly toggle code into the panel; I have long longed for a return to the tactile feel of the machine, and with that I am completely satisfied! Toggling in code, and debugging it is, to me, extremely meditative; much more so than when I'm separated by stacks and stacks of software.

Anyway, most of what I do is works well (once I get the usual "switch-os" ironed out, but even doing that is fun!) But the LAS  (load AC from switches: 7604) doesn't seem to do anything -- definitely isn't reading the switches. OSR (OR AC from switches: 7404) does work, so it CAN read the switches. Am I using LAS wrong? (Basically, instead of LAS I have to do CLA OSR -- not a huge deal, but ... concerning.)

Thanks!

'Jeff

[timr...@gmail.com]

Pretty sure that SIMH emulates a pdp-8e which has no LAS instruction and OSR is really the same thing as a group two microinstruction with the CLA bit set.  Look in the Small Computer Handbook for the 8e/8f/8m.

[Rick Murphy]

On Tue, Feb 11, 2025 at 9:35 AM timr...@gmail.com <timr...@gmail.com> wrote:

Pretty sure that SIMH emulates a pdp-8e which has no LAS instruction and OSR is really the same thing as a group two microinstruction with the CLA bit set.  Look in the Small Computer Handbook for the 8e/8f/8m.

LAS is a pseudo-op, set to 7604.

You say that LAS doesn't read the switches and CLA OSR does; but LAS = 7604 and CLA is 7200 (Group 2), OSR is 7404.   => 7604 

So this isn't making sense.

What code are you trying to use to read the switches?

    -Rick

On Monday, February 10, 2025 at 3:54:20 PM UTC-6 Jeff Shrager wrote:

I have been having a lot of fun w/my 8i. I mostly toggle code into the panel; I have long longed for a return to the tactile feel of the machine, and with that I am completely satisfied! Toggling in code, and debugging it is, to me, extremely meditative; much more so than when I'm separated by stacks and stacks of software.

Anyway, most of what I do is works well (once I get the usual "switch-os" ironed out, but even doing that is fun!) But the LAS  (load AC from switches: 7604) doesn't seem to do anything -- definitely isn't reading the switches. OSR (OR AC from switches: 7404) does work, so it CAN read the switches. Am I using LAS wrong? (Basically, instead of LAS I have to do CLA OSR -- not a huge deal, but ... concerning.)

Thanks!

'Jeff

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Rick Murphy, D. Sc., CISSP-ISSAP, K1MU/4, Annandale VA USA

[Tim Radde]

LAS is just a "CLA OSR" as opposed to OSR which does not clear the AC.  So they have to operate very similarly.  One will clear the AC and read the SR and the other won't clear the AC before or'ing the switches with the AC. How are you testing this?

[Jeff Shrager]

Hmmm. I just ran a careful test -- which I thought I'd run before -- but this time it worked. Hmmm. Probably I has a switch-o, but I was pretty careful before too. Maybe I just got myself into one of those "no matter how many time I look at it this word really looks like it's speled corectly" modes! Anyway, false alarm; Seems okay now. Thanks! (I once submitted a paper to a peer-reviewed journal about a causal model of something or other.. And we had of course VERY CAREFULLY reviewed the whole paper over and over. The editors immediately sent it back because in they realized that we probably didn't really mean the title: "A casual model of ...." :-)

[Warren Young]

On Feb 11, 2025, at 10:19, Jeff Shrager <jshr...@gmail.com> wrote:
>
> I once submitted a paper to a peer-reviewed journal about a causal model of something or other..

I just had an optometry exam and pointed out a particularly glaring (to me) error in the fine print of the intake forms.

I asked the counter staffer if that was the first part of the visual acuity examination.

She said, “Yes."