Lesson learned. I will stick to Bitsavers for my info. As far as rotate, I did know about that and because of that and other reasons, I am going to back off on the S and I think I will concentrate on the Straight-8.
On Sep 8, 2016 11:01 PM, "Johnny Billquist" <[email protected]> wrote: > On 2016-09-09 04:40, Ray Jewhurst wrote: > >> My source pertaining to the serial bus on the S being the basis for the >> Omnibus I got straight from the FAQ. To be more specific it pertained to >> the easy configurability of the 2 busses. >> > > The FAQ isn't always right. :-) > I don't think it makes any sense at all to compare the 8/S with the > Omnibus. I just did a quick check, and some controllers were usable both on > the straight 8 and the 8/S, such as the PC02, PC03, CR03C, AA01A and > probably others... So I would say that the straight 8 and 8/S was pretty > much the same, as far as peripherals were concerned. And as far as I > remember, these were pretty much the same on the 8/I as well. Check the > manuals if you want more details. :-) > > And I just found the difference in the OPR instruction for the 8/S > compared to other models, that I had some vague memory of. > On the 8/S, the Increment AC bit cannot be combined with any rotates, > since they are both done in the same clock cycle. > As far as I can remember, only the 8/S have this property, and on other > models, it is a clearly defined sequence of the different OPR bits, with > increment happening before rotates. > > Johnny > > >> >> On Sep 8, 2016 10:27 PM, "Johnny Billquist" <[email protected] >> <mailto:[email protected]>> wrote: >> >> Bob, you are right in that the PDP-5 used address 0 for the PC, and >> put the saved PC at address 1 at interrupts, which is not compatible >> with the PDP-8, and means any interrupt driven code will not work >> across the PDP-5 and PDP-8. >> >> Not sure what you mean by 0/1 for interrupts. Maybe you mean that 0 >> is where the pre-interrupt PC is saved, and execution starts at 1? >> >> Anyway... As far as the early PDP-8 models go, the 8/S is the odd >> ball out. As far as I can remember, a bunch of OPR combinations did >> not work the same (or at all) on the 8/S, compared to any other >> PDP-8 model. So special care needs to be taken when you write >> something for an 8/S. Apart from that, the machines are mostly >> upward compatible, indeed. The Omnibus machines added a few new >> things, but yes, you normally use various undocumented opcodes to >> tell the machines apart. RAR RTR is the one I know the best, but >> there are probably others too. >> >> Kermit-12 is a good source if people want to check how to tell which >> model it is running on, since that program does a pretty decent job >> of identifying pretty much all machines. >> >> Ray Jewhurst mentioned that the serial bus of the 8/S was the basis >> for the Omnibus - that is backwards and wrong in several ways. First >> of all, I'm not sure the bus was serial on the 8/S. The CPU was >> serial. >> Second, the Omnibus is most definitely not serial, and I also >> seriously doubt there are any relationship at all between the >> Omnibus and anything on the 8/S. Third, I have some vague memory >> that the Negibus was used on 8/S, but I should probably look that up. >> >> Johnny >> >> >> >> On 2016-09-09 03:53, Bob Supnik wrote: >> >> The PDP-5 is, in fact, not all that compatible, because it used >> memory >> location 0 as the PC, pushing the interrupt locations to 1/2, >> instead of >> 0/1. So any program requiring interrupts will not work on a -5 >> vs an -8. >> The PDP-5 had an IO halt/restart facility, modeled on the PDP-1 >> and >> dropped from the PDP-8, which allowed an IOT to "wait" for >> completion >> without looping and testing a flag. It does not seem to have >> supported >> an EAE or extended memory. >> >> The PDP-8 family (8, 8/S, 8/I and variants, 8/E and variants, >> 8/A) are >> superset compatible for defined operations. It's possible to >> tell them >> apart based on their behavior on undefined operations. The code >> for >> identifying a PDP-8 is out there, but I don't have it at hand. I >> remember that the behavior of RAL RAR and RTL RTR was one way of >> telling >> the 8, 8/S, and 8/I apart. >> >> Most of the work for supporting models would be in the >> peripherals, >> particularly the ones that are 'compatible' across the line >> (reader, >> punch, terminals, clock). The pre-Omnibus machines used the >> older style >> IOP1, IOP2, IOP4 pulse methodology; the Omnibus machines can >> decode all >> 8 possible combinations. Beyond that, peripherals tended to be >> distinct: >> the RK8 for the 8/I vs the RK8E for the Omnibus machines; the >> Type 552 >> DECtape controller for the -5 and -8 vs the TC01/TC08 for the >> later >> machines. >> >> The "CMOS 8s" are a whole different kettle of fish. They were >> only used >> in word processing/DECmate systems and had many unique features. >> >> /Bob >> >> On 9/8/2016 9:10 PM, [email protected] >> <mailto:[email protected]> wrote: >> >> Message: 1 >> Date: Thu, 8 Sep 2016 18:57:52 -0400 >> From: Ray Jewhurst<[email protected] >> <mailto:[email protected]>> >> To: simh<[email protected] <mailto: >> [email protected]>> >> Subject: [Simh] PDP-8: The possibilities? >> Message-ID: >> >> <CAMFEAABLe-s+qSZmm4AXyR8Pqhx3dPkiaDJb_aUXQo5hAHEt1g@mail. >> gmail.com >> <mailto:CAMFEAABLe-s%2BqSZmm4AXyR8Pqhx3dPkiaDJb_aUXQo5hAHEt1 >> [email protected]>> >> Content-Type: text/plain; charset="utf-8" >> >> After both reading and participating in some recent >> discussions, I got to >> thinking that maybe the array of PDP-8 models could be better >> represented. >> I say this because from what I have read very early PDP-8 >> code is not >> 100% >> compatible with later models conversely the PDP-5 is >> compatible with the >> early code and likewise uses a negibus like the Straight-8. >> I thank this >> could be a rewarding experience for some of us and since I >> can't work I >> would be able to help coordinate, write pseudo code and beta >> test. If >> anyone is interested in this let the discussion begin. >> >> Thanks >> Ray >> >> >> _______________________________________________ >> Simh mailing list >> [email protected] <mailto:[email protected]> >> http://mailman.trailing-edge.com/mailman/listinfo/simh >> <http://mailman.trailing-edge.com/mailman/listinfo/simh> >> >> >> >> -- >> Johnny Billquist || "I'm on a bus >> || on a psychedelic trip >> email: [email protected] <mailto:[email protected]> || >> Reading murder books >> pdp is alive! || tryin' to stay hip" - B. Idol >> >> _______________________________________________ >> Simh mailing list >> [email protected] <mailto:[email protected]> >> http://mailman.trailing-edge.com/mailman/listinfo/simh >> <http://mailman.trailing-edge.com/mailman/listinfo/simh> >> >> >> > > -- > Johnny Billquist || "I'm on a bus > || on a psychedelic trip > email: [email protected] || Reading murder books > pdp is alive! || tryin' to stay hip" - B. Idol >
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