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18

The Heathkit H11 was available either as a kit or pre-assembled. It never became really popular in the West, but it was one of the most powerful PCs available in 1978. It used the LSI-11 small format of the PDP-11, and came with 4 kwords of memory for $1295. (That is 8 kbytes, but DEC preferred to refer to memory as register size, which was 16 bits.) It ...


16

However, at that time, the world had not yet settled on octets. I beg to differ. If you look through brochures and manuals of next to all manufacturers, they tried hard to be IBM compatible at least for data exchange. Being IBM compatible was effectively mandatory for the whole industry and with the /360 introduction in 1964 the size of a byte (for ...


15

It can be found in implementations of zfs such as OpenZFS, inherited from the Solaris Kernel Memory C header file: https://github.com/openzfs/openzfs/blob/master/usr/src/uts/common/sys/kmem_impl.h line 80 #define KMEM_FREE_PATTERN 0xdeadbeefdeadbeefULL Quote from the magic number wiki page: "Dead beef", Famously used on IBM systems such as the RS/...


14

If you compare the octal opcodes for the skip instructions, a bcd | ||| 7500 SMA = 111 101 000 000 7440 SZA = 111 100 100 000 7420 SNL = 111 100 010 000 | ||| 7510 SPA = 111 101 001 000 7450 SNA = 111 100 101 000 7430 SZL = 111 100 011 000 you see that in each group, there are three conditions that ...


13

ARPANET isn't the only context in which the world of PDP-10 computing ran into data paths that used octets for framing. Four other contexts come to mind: 9 track magnetic tape, PDP-11 file exchanges, DECnet, and Kermit. 9 Track Magnetic Tape. 9 Track tape rapidly became the most popular standard as IBM transitioned from 36 bit processors to the 360. ...


10

DECnet is more of a protocol suite than a physical hardware standard. So asking what kind of physical connector it uses is kind of like asking what kind of physical connector TCP/IP uses -- the answer is, it uses whatever connector you need to use for the particular data link layer you're running DECnet on top of. If you are running DECnet over Ethernet, ...


9

In a similar vein, Algol-68R on ICL 1900 (a 24-bit machine) initialized memory to -6815700, which when displayed as text (four 6-bit characters), spelled 'F00L', as well as possessing numerous other virtues. https://en.wikipedia.org/wiki/ALGOL_68-R#F00L


9

The first and most important point to keep in mind is that the VAX wasn't initially designed as a new architecture, but an extension to the basic PDP-11 structure to break its 64 KiB boundaries. Early implementations even offered a hardware-based PDP-11 mode. MMU page size in VAXen is just 512 bytes Which is also the block size of most DEC disk drives (...


9

I can only provide my memories of a dozen or so years of programming for these DEC terminals. The 'new' character at the right hand end of the screen is inverse video. If I recall correctly, on the VT320 onwards there was a configuration setting to change this, such that it would appear not inverted.


9

36-bit computers were used to communicate through channels which were not 36-bit. ARPANET packets are not the only one, paper and magnetic tapes, connections to terminals, ... have also their frame which is not 36-bit. Protocols and OS of the time were used to define various ways to transform 36-bit words in smaller units (search here for SET TAPE FORMAT ...


8

It's possibly a stretch, but the General Instruments CP1600 which was in the Intellivision, though otherwise unsuccessful, was based on the PDP-11 architecture. The Intellivision was a product of Mattel, not GI, so it's the one commercial machine that opted to use the chip rather than being the machine the chip was designed for. General Instruments designed ...


8

Yes, at a physical level there was some commonality, but not at as high a level the question references. In the mid 1960s, DEC sold a line of simple logic modules, known as flip chips. The PDP-7 and the original PDP-8 were built (at least partially) out of the R-series modules, though there were some custom modules created just for them (e.g. a W130 ...


8

It's really more of a conjecture, but if it is considered suitable as an answer: Already in early TECO, the letter q ("quantity") was used to retrieve the value of a register. That might have been the reason to call them Q-registers. Trying to trace reasons for why things are named a certain way is always difficult; they way this usually goes is that ...


7

This information is based on information from the DEC VT220 Technical Manual. I've not actually tried this out myself. TLDR: Yes, it's likely to work, and quite cheap to try using a sub-$1 BNC to RCA adapter if you already have an RCA-RCA video cable. Section 1.4 says that the "BNC connector for composite video output to an optional slave monitor" uses "...


7

There were obviously no same parts that were doing any of those operations. The DEC hardware evolved from transistor technology (PDP-1, PDP-8, etc.) to medium-scale IC logic like standard TTL (PDP-8/E, early PDP-11) and eventually to large-scale ASIC CPUs like LSI-11 or 6100 PDP-8 clone. The similarity of instruction sets has nothing to do with the actual ...


7

My take is that this scheme has been invented the same way everything has been invented: Slowly, by evolution and combining existing ideas, and not "from scratch" by a strike of genius. The carry flag has been around a long time before that (other PDPs, and previous computers). Branches or skips that test the carry flag have also been around (other PDPs, ...


7

There was Terak 8510/A - a graphic workstation with the LSI-11 compatible processor, a graphical frame buffer (hardware-scrollable the same way as in the BK-0010), and a text mode with downloadable fonts, although admittedly too expensive to be a home computer. In some sense BK-0010 looks like a stripped-down Terak (no text mode, less RAM, etc.), but the ...


7

In Israel, in the early 1980s (I started work as an accountant in 1982 so I don't know how long the system had been in use prior to this date), all the kibbutzim of an area used to connect to one PDP-11 which was run from a communal computing centre. Each kibbutz had one data line. We had programs for accounting and a precursor of what was to be ERP, as well ...


6

Bitsavers has some PDFs of printouts of tsExec1.4. Not sure if this is complete. There's a lot of PDP-10 software e.g. at trailing-edge, I suppose at least some of that could be adapted to run on the PDP-6 (but you probably already thought of that).


5

There are a couple of files at http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/, e.g. Andrew C. Goldstein, Files-11 On-Disk Structure Specification, First Edition, Digital Equipment Corporation, 19 June 1975 at http://bitsavers.trailing-edge.com/pdf/dec/pdp11/rsx11/Files-11_ODS-1_Spec_Jun75.pdf Andrew C. Goldstein, Files-11 On-Disk Structure ...


4

The program was MAC HACK VI. This link doesn't give access to the program, but it may give you some leads about where to find it. It was a chess playing program, and a good one for its time frame. https://chessprogramming.wikispaces.com/Mac+Hack Also, here's a link to pdp- TECO. The best text editor around in 1965. This link does have a Download button,...


4

Old versions of the Monitor: http://pdp-6.trailing-edge.com/ PDP-6 notes from ITS, includes some PDP-6 programs: https://github.com/PDP-10/its/issues/278


4

It is an artifact of the underlying electronics. The PDP-8 had a very small instruction set of just 8 elementary instructions. The PDP-8 used core memory, predating RAM. Remember that the act of reading a location of core memory had the side effect of setting it to zero - something I suspect would give modern software writers kittens. The AND and OR groups ...


4

The approach I remember liking on some terminals of that era that I liked (not sure if I noticed DEC ones doing this, or some other company's) was that there were four intensity levels (including off). Normal text was 2/3 intensity. Inverse text was black on a 1/3 intensity background. Highlighted was full intensity. Highlighted reverse was 2/3 intensity ...


4

There were one-chip versions both of the PDP-8/LSI-8 (the models are called DECmate, using the Intersil/Harris 6100 chip) and the PDP-11/LSI-11 (J-11 or "Jaws" chip, used in a range of PDP-11 models). Also, these were hardly "home computers" due to their price point. They would be typically be bought by labs or research institutions, both in academia and ...


4

This is a frame from MIT AI film #43. I'm not sure what year it's from, but it seems to be from the PDP-6 era. The code is very similar to old ITS source code, so it's likely this is a tiny fragment of PDP-6 ITS. The use of "↓₁₄" identifies this as text displayed by PDP-6 TECO. Transcription, including a few more lines visible in the film: LDB B,...


3

TLDR: TECO uses single-character commands. When extending TECO to add registers to store numeric values, there was a limited set of unused characters left for the commands associated with this functionality. q was chosen as one of these command characters because it could serve as a mnemonic for "quantity." This led to the numeric registers being called "Q-...


3

As I recall, the PDP 1 through 6 were built from system modules, and these came out before flip-chips. The 7 was like the 4, only the 7 had flip chips. The 8 was like the 5, only the 8 had flip chips. The 10 was like the 6 only the 10 had filp chips. The 11 was a departure in architecture in several ways. Word size, instruction set, memory addressing, ...


3

PAGEN is a 'language' (well, more of a configuration file) used in RT11 on PDP-11 for system generation.


3

As already stated, the question misses the point of what DECNet is. This is a common misconception regarding networks. DECNet sits at the Transport and Network levels of the OSI model of networking. The physical connector is only relevant at the Physical or Data Link levels. I used DECNet extesively for several years, on Thick-wire, Thin-wire, Optical, ...


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