jack@cwi.nl (Jack Jansen) (01/01/70)
Hmm, I've seen so much misinformation on PDP-11 history by now, I might as well throw in my own 10 cents of misinformation: 1st generation. 11/20 Basic pdp-11, no FPU, no MMU, 18 bit unibus (of which only 16 were useable). 2nd generation. 11/45 The first big thing. FPU, MMU (separate I/D), 2 18-bit unibusses. The 11/55 seems to be a slightly modified version of this thing. 11/10 Low-end machine. No FPU, no MMU. 18 bit unibus with only 16 bits useable. Optional Extended Instruction Set that gave you DIV, shift-multiple and some other goodies. Also known as 11/05 (OEM) and GT-40 (with vector scope) 3rd generation. 11/40 In between 10 and 45. Optional MMU, optional EIS, optional (incompatible) FPU. 18 bit unibus. MMU didn't have separate I/D space, no support for instruction backup, no PIRQ, no soft SP interrupt, etc. ==11/35. 11/70 New high-end machine. FPU, MMU (superset of 45 MMU), 18 bit unibus and 22 (or is it 24?) bit memory bus. Massbus (fast bus for mass-storage peripherals). MMU had a 'unibus map', so unibus peripherals could reach all of memory. 4th generation. 11/34 Replacement for 11/40. Basically the same thing in newer technology, with EIS and MMU standard, and optional (11/45 compatible) FPU. 11/04 11/10 replacement in newer technology. From now on, things become fuzzy. But, just for your misinformation, I'll tell what I know, in roughly chronological order. 11/60 Meant to be new high-end, but failed completely. Very fast CPU with user-loadable microcode (but only for one or two instructions:-(), MMU, FPU, but only 18 bit memory bus, and no separate I/D. Grumpf. 11/780 First VAX. Basically an 11/04 with an extra 32 bit processor and lots of extra busses. Also slightly more expensive. 11/03 LSI version of 11/04. First Q-bus machine. The Q-bus is a poor-mans-unibus: multiplexed A/D lines, only one level of interrupts, etc. 11/23 LSI version of 11/34 with Q-bus. 11/24 Ditto, only this one had a unibus, a 22 bit memory bus and a unibus map. 11/74 LSI version of 11/70, with qbus. 11/84 Souped up version of 11/74. -- Jack Jansen, jack@cwi.nl (or jack@mcvax.uucp) The shell is my oyster.
roy@phri.UUCP (Roy Smith) (10/04/87)
In article <29933@sun.uucp> guy%gorodish@Sun.COM (Guy Harris) writes: > a PDP-11/55 (which was an 11/45 with bipolar memory hung off a fast > memory bus). The closest I ever came to one of these was 1) reading the CPU hardware manual and 2) poking around in one which had been discarded. Anybody ever actually have one of these beasties? Must have run like greased lightening. How many were actually made? As I remember, the 11/45 was capable of having a certain amount (8kbytes?) of MOS or bipolar ram in place of some of the core. Anybody ever have a 45 so equiped? Did it make much difference? -- Roy Smith, {allegra,cmcl2,philabs}!phri!roy System Administrator, Public Health Research Institute 455 First Avenue, New York, NY 10016
ron@topaz.rutgers.edu (Ron Natalie) (10/04/87)
The memory on a 11/45 are the so called "fast-bus." Similar to the regular Tunabus but faster. It is certainly possible to install MOS memory in there. We had EMM memorry with a hacked fast-bus controller on the 11/45 at JHU, and yes it was much faster than the all-core 11/45's that were kicking around. -Ron who woo - Strange joke, Local origin
loverso@encore.UUCP (John LoVerso) (10/06/87)
In article <2949@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: > As I remember, the 11/45 was capable of having a certain amount > (8kbytes?) of MOS or bipolar ram in place of some of the core. Anybody > ever have a 45 so equiped? Did it make much difference? The answer is in the time(1) manual page from 4.3 dating back to v7: "On a PDP-11, the execution time can depend upon what kind of memory the program happens to land in; the user time in MOS is often half what it is in core." John Robert LoVerso Encore Computer Corp encore!loverso, loverso@multimax.arpa
tsmith@gryphon.CTS.COM (Tim Smith) (10/07/87)
In article <2949@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >In article <29933@sun.uucp> guy%gorodish@Sun.COM (Guy Harris) writes: >> a PDP-11/55 (which was an 11/45 with bipolar memory hung off a fast >> memory bus). > The closest I ever came to one of these was 1) reading the CPU >hardware manual and 2) poking around in one which had been discarded. >Anybody ever actually have one of these beasties? Must have run like >greased lightening. How many were actually made? Was it a faster 11/45, or an OEM 11/60? I don't know, but I do remember that DEC had a habit of producing a machine (11/10, 11/40) for "end users", then a version -5 for OEMs (11/05, 11/35). I've had little experience with the 11/60 (other than a few evenings sysgen'ing RSX on one), but as I remember the 11/60 was a very special beastie, with, I believe, user- writeable microcode. Not at all like a typical PDP-11. But please correct me if wrong--I claim no expert knowledge with 11/60's. The one I used briefly was the property of a physics department, and I was told that it was sold to them as DEC's ultimate Fortran engine (circa 1980 here). -- Tim Smith INTERNET: tsmith@gryphon.CTS.COM UUCP: {hplabs!hp-sdd, sdcsvax, ihnp4, ....}!crash!gryphon!tsmith UUCP: {philabs, trwrb}!cadovax!gryphon!tsmith
fouts@orville.nas.nasa.gov (Marty Fouts) (10/07/87)
It has been a few year (;-) since I played with PDP 11/XX machines, but let me try to dredge some data from memory. The 11/60 was suppose to be the be all / end all of the PDP (as opposed to LSI) 11/XX machines. (The distinction was that PDP engines were all TTL and LSI were lsi) It was late. (Anybody surprised?) So DEC whipped together a hacked up version called the 11/70; which was the last core memory "tall boy" cabinet PDP 11. The 11/60 ended up in a "low boy" cabinet (half height - double width) and had MOS memory in most (all?) cases as well as a Writable Control Store. The 70 had massbus adapters, a unibus and two data paths from the processor to memory, so became the more popular machine. We managed to support 30-50 people on a 70 running RSTS/E, mostly doing school adminstration (payroll, grades, etc) and learning Basic, Fortran and PASCAL; something we were never able to get an 11/780 to do. That 70 had 256kb of mos memory and 4 RL02 (5 MB each) disk drives. . . Down the road, a different school at a 60 and was able to support about the same number of people, so I guess the two machines were roughly equivalent. Marty
guy%gorodish@Sun.COM (Guy Harris) (10/07/87)
> Was it a faster 11/45, or an OEM 11/60?
No, it was a faster 11/45, according to the PDP-11 04/34/45/55 Processor
Handbook:
The PDP-11/55 is a bipolar memory based computer designed for greater
processor and system performance through the use of a dedicated
internal semiconductor memory bus. ... The PDP-11/55 can be expanded
up to 248K bytes with the aid of the memory management unit which is an
integral part of the central processor. The fast floating point
processor operates as an integral part of the central processor...
...
The PDP-11/45 has a cycle time of 300 nsec and performs all arithmetic
and logical operations required in the system. A Floating Point
Processor mounts integrally into the Central Processor as does a Memory
Management Unit...
So I guess the 11/55 was a "loaded" 11/45, with semiconductor memory (which is
not mentioned in the description of the 11/45) and a standard MMU and FPP.
By the time the 11/60 came out, the "version - 5" for end-users convention
was gone. Early draft versions of the 11/34 manual mentioned an 11/39, but
unless they put out a few early ones I don't think they ever put an 11/39 label
on that machine.
The 11/60 was, indeed, a machine with user-writable microcode; it also had
FPP-compatible microcode, so you could execute FPP instructions even if you
didn't have an FPP. Unfortunately, it didn't support 22-bit addressing.
Guy Harris
{ihnp4, decvax, seismo, decwrl, ...}!sun!guy
guy@sun.comkent@decwrl.dec.com (Christopher A. Kent) (10/08/87)
A very large difference between the 11/60 and 11/70 was that the 11/70 had split instruction and data spaces. So operating systems that knew how to make use of this feature (that is, Unix) could run much larger programs. The 11/45 was the only other 11 to have this feature. DEC never produced an operating system that took advantage of it, because EVERYTHING was supposed to be able to run on the least common denominator hardware. On the other hand, I've heard all sorts of stories about what they're doing to squeeze more and more bits into RSTS, so who knows if this is still true? chris -- Chris Kent Western Research Laboratory Digital Equipment Corporation kent@decwrl.dec.com decwrl!kent (415) 853-6639
pcm@ogcvax.UUCP (Phil Miller) (10/08/87)
One more time... Can we PLEASE MOVE THIS DEBATE TO ANOTHER FORUM? Numerous complaints about this discussion have been posted. PLEASE take the hint.
dave@sdeggo.UUCP (David L. Smith) (10/08/87)
In article <72@bacchus.DEC.COM>, kent@decwrl.dec.com (Christopher A. Kent) writes: > A very large difference between the 11/60 and 11/70 was that the 11/70 > had split instruction and data spaces. So operating systems that knew how > to make use of this feature (that is, Unix) could run much larger programs. > > The 11/45 was the only other 11 to have this feature. DEC never produced an > operating system that took advantage of it, because EVERYTHING was supposed > to be able to run on the least common denominator hardware. Well, as of 1982 or thereabouts you could build a split I&D kernel and I believe that you could specify it when you linked (TKB'd) a program. Ah, nostalgia... -- David L. Smith {sdcsvax!amos,ihnp4!jack!man, hp-sdd!crash, pyramid}!sdeggo!dave sdeggo!dave@amos.ucsd.edu "How can you tell when our network president is lying? His lips move."
ron@topaz.rutgers.edu (Ron Natalie) (10/08/87)
11/55's are 11/45 CPU's with different packaging (bipolar memory and a blue front panel). 11/60's are indeed the user writable microcode machines. They have the silly 11/34 style front panel and no split-I/D or other 45/70 specific features.
eeproks@pyr.gatech.EDU (Ken Seefried iii) (10/09/87)
In article <3019@ames.arpa> fouts@orville.nas.nasa.gov.UUCP (Marty Fouts) writes: > . The 11/60 was suppose >to be the be all / end all of the PDP (as opposed to LSI) 11/XX >machines. (The distinction was that PDP engines were all TTL and LSI >were lsi) This is not quite true. I have a PDP-11/2 and it is definately of LSI construction. -------------------------------------------------------------------------- K. J. Seefried iii School of Information and Computer Science P.O. Box 30104, Georgia Insitute of Technology, Atlanta Georgia, 30332 uucp: ...!{decvax,hplabs,ihnp4,linus,rutgers,seismo}!gatech!gitpyr!eeproks \-!gatech!gt-stratus!ken internet: eeproks@pyr.gatech.edu || ken@stratus.gatech.edu
ron@topaz.rutgers.edu (Ron Natalie) (10/09/87)
The RSX use of split I/D came in RSX-11M+ which allowed you to use split I/D in supervisor mode. -Ron What no mark instruction?
billa@ihlpl.ATT.COM (Anderson) (10/09/87)
In article <15422@topaz.rutgers.edu>, ron@topaz.rutgers.edu (Ron Natalie) writes: > 11/55's are 11/45 CPU's with different packaging (bipolar memory and a blue > front panel). 11/60's are indeed the user writable microcode machines. They > have the silly 11/34 style front panel and no split-I/D or other 45/70 > specific features. This material has no valid contribution to MINIX. Please do not post material that has nothing to do with MINIX.
billa@ihlpl.ATT.COM (Anderson) (10/09/87)
In article <15422@topaz.rutgers.edu>, ron@topaz.rutgers.edu (Ron Natalie) writes: > 11/55's are 11/45 CPU's with different packaging (bipolar memory and a blue > front panel). 11/60's are indeed the user writable microcode machines. They > have the silly 11/34 style front panel and no split-I/D or other 45/70 > specific features. This material has no contribution to the MINIX newsgroup. Please be kind enough not to post such material to comp.os.minix Thanx
fay@encore.UUCP (Peter Fay) (10/09/87)
In article <89@piring.cwi.nl} jack@cwi.nl (Jack Jansen) writes: } 11/20 Basic pdp-11, no FPU, no MMU, 18 bit unibus (of which } 11/45 The first big thing. FPU, MMU (separate I/D), 2 18-bit } 11/10 Low-end machine. No FPU, no MMU. 18 bit unibus with } 11/70 New high-end machine. FPU, MMU (superset of 45 MMU), } 11/34 Replacement for 11/40. Basically the same thing in } 11/04 11/10 replacement in newer technology. } 11/60 Meant to be new high-end, but failed completely. Very } 11/780 First VAX. Basically an 11/04 with an extra 32 } 11/03 LSI version of 11/04. First Q-bus machine. The Q-bus } 11/23 LSI version of 11/34 with Q-bus. } 11/24 Ditto, only this one had a unibus, a 22 bit memory } 11/74 LSI version of 11/70, with qbus. } 11/84 Souped up version of 11/74. I had the pleasure of using a PDP 11/70 at Hartford State Tech. Col. which was upgraded (according to the DEC rep) to the only existing (at that time) PDP 11/80 (?) in the country. Has anyone heard of the beast? -- peter fay fay@multimax.arpa {allegra|compass|decvax|ihnp4|linus|necis|pur-ee|talcott}!encore!fay
pdb@sei.cmu.edu (Patrick Barron) (10/10/87)
In article <89@piring.cwi.nl> jack@cwi.nl (Jack Jansen) writes: > 11/23 LSI version of 11/34 with Q-bus. > 11/24 Ditto, only this one had a unibus, a 22 bit memory > bus and a unibus map. The F-11 based machines (the 11/23 and 11/24) were also much slower than the 11/34. > 11/74 LSI version of 11/70, with qbus. > 11/84 Souped up version of 11/74. The 11/74 was a prototype multiprocessor 11/70. I think only one was ever made. The 11/73 is the Q-bus 11/70 (based on the J-11 chipset). The 11/83 is a faster 11/73 with a special memory bus (the PMI bus). The 11/84 is a Q-bus 11/83. --Pat.
henry@utzoo.UUCP (Henry Spencer) (10/11/87)
> ... Down the road, a different school at a 60 and was able to > support about the same number of people, so I guess the two machines > were roughly equivalent. Choke cough. No. The 60 was grossly inferior to the 70 in most ways: hardware address space, integer processing speed, I/O bandwidth, etc. Its optional floating-point hardware was (I think) the same as the 70's. Otherwise, it was a piece of junk. There has been persistent speculation that the original 60 was much faster than the one that was finally released to the customers; it is hard to see how it could possibly deserve that model number otherwise. A well-equipped 45 was a better machine, and the 55 could run rings around it. The (slightly later) 44 was superior to the 60 in every way except floating-point, where the 44's lousy FPP (a slight variant of the 34 FPP) held it back. -- "Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology "the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henry
henry@utzoo.UUCP (Henry Spencer) (10/11/87)
> The 11/45 was the only other 11 to have [split space]. No, later large 11s (44, 73, 8x) have it. It took them a while to learn that it was important, but they eventually did. Having Bell Labs / AT&T refuse to buy the 11/60 for this reason (I was told) made quite an impression on DEC. > DEC never produced an operating system that took advantage of it... I think this changed as the DEC operating systems grew. I'm not sure of that; I lost interest in DEC operating systems in early 1975 when Fifth Edition Unix came out. -- "Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology "the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henry
mason@tmsoft.UUCP (10/11/87)
In article <8740@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: >Choke cough. No. The 60 was grossly inferior to the 70 in most ways: >hardware address space, integer processing speed, I/O bandwidth, etc. The only interesting thing about the 11/60 is that it had (because of the (writable) microcode) many interesting (to some) instructions. Not having my PDP-11 Processor Handbooks right at hand (Where did I put them? They were here only 6 years ago) and never having programmed one, I'm not sure of all the instructions, but they included string and BCD operations (COBOL city, S/360 killers, etc.). I'm not sure any compilers ever produced code for the /60, as it was the only machine that had these instructions. ../Dave Mason
dennis@utgpu.UUCP (10/11/87)
In article <89@piring.cwi.nl> jack@cwi.nl (Jack Jansen) writes: > >I'll tell what I know, in roughly chronological order. [...] > 11/780 First VAX. Basically an 11/04 with an extra 32 > bit processor and lots of extra busses. Also slightly > more expensive. > 11/03 LSI version of 11/04. First Q-bus machine. The Q-bus > is a poor-mans-unibus: multiplexed A/D lines, only > one level of interrupts, etc. The chronology is quite rough here. I think the 11/03 might have been available as early as 1973 or 1974. I definitely saw my first one in 1976, a year or two before 11/780's were sold (indeed, the console subsystems in 11/780's include an 11/03). I remember this well, that 11/03 was the first computer I ever wanted to take home. I eventually did, but much later, I use the CPU as a paper weight. The Q-bus had 4 interrupt request lines from the beginning, like the Unibus, though the 11/03 only supported one level. The Q-bus did (and still does) only have one daisy-chained interrupt acknowledge line, however. I think the latter is the reason why the microVax always sets the processor priority to spl7() when servicing an interrupt (and why the clock on early Ultrixes loses time) no matter what the bus priority of the requesting device is. You can't tell for sure what the priority of the device which ends up taking the interrupt is. > 11/23 LSI version of 11/34 with Q-bus. But with 22 bit addressing. I remember cutting traces on old peripheral cards which used a couple of the new address lines as grounds so I could run an 11/23 in 22 bit mode and use the extra memory as a RAM disk for RT-11. > 11/74 LSI version of 11/70, with qbus. I think this is really an 11/73. And it probably wasn't exactly like an 11/70, it took years before DEC software would actually let you run a separate I/D space program, even through the same OS would do this fine on an 11/70. -- Dennis Ferguson Mechanical Engineering University of Toronto
lawitzke@eecae.UUCP (John Lawitzke) (10/13/87)
Just how adle minded are you people? For the past couple of weeks
this PDP discussion has been spilling over to comp.os.minix which
it has nothing to do with! Several people have several times posted
articles asking that the crossposting be controlled! I'm sure you idiots
wouldn't like it if we crossposted MINIX articles to comp.arch and
comp.unix.wizards now would you? So show comp.os.minix some
consideration! &^%*&^%*&^% stupid &*^^%& snarl arffs!
ps- I really don't think you people are idiots, I just figure that
strong language will finally get your attention and you'll wake up!!!!
--
j UUCP: ...ihnp4!msudoc!eecae!lawitzke
ARPA: lawitzke@eecae.ee.msu.edu (35.8.8.151)jal@oliveb.UUCP (Benjamin G. Golding) (10/13/87)
> > 11/23 LSI version of 11/34 with Q-bus. > > But with 22 bit addressing. I think there were two versions of this model: the vanilla 11/23 had only 18 address lines, the 11/23+ had the full 22 on its Q-bus. Ben. -- Buy me, remember my books... St. Neresa of the Tet
tsmith@gryphon.CTS.COM (Tim Smith) (10/14/87)
In article <8741@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes: +===== | > The 11/45 was the only other 11 to have [split space]. | | No, later large 11s (44, 73, 8x) have it. It took them a while to learn | that it was important, but they eventually did. Having Bell Labs / AT&T | refuse to buy the 11/60 for this reason (I was told) made quite an impression | on DEC. | | > DEC never produced an operating system that took advantage of it... | | I think this changed as the DEC operating systems grew. I'm not sure of | that; I lost interest in DEC operating systems in early 1975 when Fifth | Edition Unix came out. +===== This last paragraph is one of the more provocative statements that I have seen about PDP-11's. For demonstrating the wonders of Unix, for simple time-sharing, and for advanced (for 1975) text-processing, I'm sure that Unix V5 must have been brilliant in its time (wasn't it also an element known as unobtanium?). In my experience, most PDP-11s in the mid-70's made their way into labs, or onto factory floors. There, I am quite sure, Unix V5 would have shined not at all. For whatever you may think of RT (passable for the demands), or RSX (no comment), or RSTS (passable for the demands), they did do useful work. What *were* you doing with 11's in 1975? Just a curious question... +===== | "Mir" means "peace", as in | Henry Spencer @ U of Toronto Zoology | "the war is over; we've won". | {allegra,ihnp4,decvax,utai}!utzoo!henry +===== Actually, if I remember my college Russian correctly, "mir" means both "peace" and "world". That makes "mir" seem a most peaceable word. -- Tim Smith INTERNET: tsmith@gryphon.CTS.COM UUCP: {hplabs!hp-sdd, sdcsvax, ihnp4, ....}!crash!gryphon!tsmith UUCP: {philabs, trwrb}!cadovax!gryphon!tsmith
ESC1332%ESOC.BITNET@wiscvm.wisc.edu (K.Keyte) (10/14/87)
If you recall, the PDP-11 computer didn't actually exist. No such machine was ever made, and far from the memory being virtual, the whole computer was virtual - it's nice to dream though, and would those who wish to do so do it somewhere else; perhaps a PDP-11 or DREAM list would be appropriate. Gabriel
braun@m10ux.UUCP (MHx7079 mh) (10/15/87)
In article <3215@eecae.UUCP>, lawitzke@eecae.UUCP (John Lawitzke) writes: > Just how adle minded are you people? For the past couple of weeks > this PDP discussion has been spilling over to comp.os.minix which > it has nothing to do with! Several people have several times posted . . . > ps- I really don't think you people are idiots, I just figure that > strong language will finally get your attention and you'll wake up!!!! On the contrary, I have greatly enjoyed reading the PDP-11 articles. They have been very educational, and have helped me better understand what Minix does by comparing it to other systems. If the articles weren't here, I would not have time to find them in another newsgroup. -- Doug Braun AT+T Bell Labs, Murray Hill, NJ m10ux!braun 201 582-7039
dave@onfcanim.UUCP (Dave Martindale) (10/16/87)
In article <2949@phri.UUCP> roy@phri.UUCP (Roy Smith) writes: >In article <29933@sun.uucp> guy%gorodish@Sun.COM (Guy Harris) writes: >> a PDP-11/55 (which was an 11/45 with bipolar memory hung off a fast >> memory bus). > > As I remember, the 11/45 was capable of having a certain amount >(8kbytes?) of MOS or bipolar ram in place of some of the core. Anybody >ever have a 45 so equiped? Did it make much difference? From "PDP-11/45 Processor Handbook, 1973" (somewhat yellowed by now): The processor used in the 11/45, 11/50, and 11/55 actually had two data paths to memory. One went to the normal system Unibus, and the other was a dedicated data path that went only to the dedicated local memory controllers. On the 11/45, there were no solid-state memory controllers installed, so all accesses to memory went via the Unibus and the special path was unused. On the 11/55, there was 1 or 2 special memory controllers connected to this interface, via dedicated slots in the CPU backplane. (I think DEC called this special interface the FASTBUS). Each memory controller could have bipolar or MOS memory attached to it. The bipolar memory was 300 ns access time, and you always used 4 boards on a controller, which gave you 4kw (16-bit words). Mos memory was 450 ns access with 4kw per card, and a controller could have 1-4 MOS boards giving 4-16kw. Each controller was all bipolar or all MOS, but one controller could have bipolar and the other MOS, giving a maximum complement of 8kw bipolar, 32kw MOS, or 4k bipolar plus 16K MOS. (Of course, you could also put memory on the main Unibus, but access was slower). These controllers were dual-ported, so they watched both the CPU memory interface and the UNIBUS, allowing peripherals to have access to the memory transparently. It should have made a big difference in performance; the 11/45 was capable of executing simple instructions (register-register add, failed conditional branch, etc.) one every 300 ns, as fast at they could be fetched from bipolar memory. Compare this to something like a VAX 780, or the 800 ns or so necessary to get a word from Unibus memory. The only 11/55 I ever saw was used at Waterloo to run a programming lab where lots of undergrads edited text files and then submitted the output to the local HASP machine for compile and execute. It did handle quite a few users (60?) but the system didn't let them do much. The above description is actually a simplification; the solid-state memory controllers were actually dual-ported to a second unibus, called "unibus B", not the main unibus (unibus A) which connected to the peripherals and other memory. Normally, a simple jumper was used to short the two unibuses together, in which case they became a single bus and solid-state memory really was dual-ported with the main unibus. However, if you removed this jumper, you could connect unibus B to another CPU's unibus, allowing that processor dual-ported access to the solid-state memory. The main CPU contained a bus arbitrator only for unibus A, so whatever unibus B was connected to had to provide its own arbitrator (e.g. another CPU). The 11/45 had interlocked memory access instructions, so multi-processor semaphores were possible via the shared memory. Another piece of trivia, and the reason the /45 was my favourite model of the PDP-11: the Unibus arbitrator ran even when the CPU was halted - it was a separate piece of hardware. Thus, you could use the console switches to deposit cylinder and track addresses and a "read" command into a disc controller, and the data appeared in memory. No boot code was necessary. For other members of the family, the bus arbitrator ran only when microcode was executing, so you needed to be executing instructions (just branch-to-self would do) in order for DMA to memory to work.
BECKER%HUMBER.BITNET@wiscvm.wisc.edu (Bruce Becker) (10/16/87)
W@HAT THE HELL IS THIS DEC-11 NOSTALGIA DOING IN THE MIDST OF A MINIX DISCUSSION - BEGONE YE DEVILS! Seriously, if you people want to stay on that track it should be moved to a discussion group that's more in tune with your concerns. I can appreciate that there are some questions about MINIX et al. where memory management issues are concerned - but thecurrent cpu's in question for MINIX ports are 68000 etc. (unless someone is actually putting it up on a DEC-11 machine...) for I&D hassles/solutions... I'd like to see some discussion on how to produce a similar "segmented" environment in the 68000 universe similar to the 80x86 - i.e. the porting issues to Atari/Amiga... Anyone able to share some experience on this? Bruce Becker Humber College Etobicoke, Ont.
BECKER%HUMBER.BITNET@wiscvm.wisc.edu (Bruce Becker) (10/16/87)
N O M O R E D E C _ 1 1 ! stopstopstopstopstopstop
guy@gorodish.UUCP (10/28/87)
> Another piece of trivia, and the reason the /45 was my favourite model > of the PDP-11: the Unibus arbitrator ran even when the CPU was halted - > it was a separate piece of hardware. Thus, you could use the console > switches to deposit cylinder and track addresses and a "read" command > into a disc controller, and the data appeared in memory. No boot code > was necessary. For other members of the family, the bus arbitrator > ran only when microcode was executing, so you needed to be executing > instructions (just branch-to-self would do) in order for DMA to memory > to work. I think this worked on the 11/34 as well; the instructions for bringing up V6 on an 11/34 with no console switches involved stuffing addresses and commands into the RK05 controller's registers in order to yank the requisite blocks from "/unix" and "/etc/init" in order to patch them and to write them back. Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com
BECKER%HUMBER.BITNET@wiscvm.wisc.edu (Bruce Becker) (10/31/87)
Please Dave DO NOT (repeat: D O N O T) say anything more about PDP-11's in this MINIX discussion group! No-one cares to hear about it here. There is a proper venue elsewhere in the net in which this discussion could be heard as signal, rather than the noise is has become in tis MINIX forum... Thanks, Bruce Becker
mmdf@udel.UUCP (11/02/87)
Uhhh, Guy, this is a MINIX discussion group, not a PDP-11 one. I'm sure there are excellent venues for such a discussion, but a MINIX forum just doesn't seem like the appropriate one... Cheers, Bruce Becker
ESC1332%ESOC.BITNET@wiscvm.wisc.edu (K.Keyte) (11/02/87)
My God you people are boring. My message wasn't ABOUT PDP-11 but asking people not to send any more messages. Can you read? If so, why didn't you read it?