Bringing in a convenient form for work micro-computers UKNTS Electronics MS 0511 architecture PDP-11

    Good afternoon comrades Khabrovchane. Today I decided to please you with the first part of the history of bringing the Soviet micro-computer of the UKSC Electronics MS 0511 of the DEC PDP-11 architecture into a convenient form for work.

    For me, this old car is interesting not only because it is built on the architecture of PDP-11 and is not a direct clone of some kind of “western” machine, but also nostalgic. This was the first real computer I dealt with, before that there was only experience with the programmable calculator Electronics MK-61. Which still works for me and I use it when I need to make calculations, and sitting and coding in C ++ is too lazy. His reverse Polish entry well “puts into a stupor” of modern people, with their question “How to count on it?” Where is the button equal? ​​”But the article is not MK-61, although of course it is also interesting, but about the UKSC.

    I will not retell the history of creation and the performance characteristics of the UKSC, those who wish can read the article on Wikipedia by reference .

    Other links with descriptions and photos are also easily accessible in Google, as well as the emulator which can be viewed here . There is documentation, an archive of software and everything else if anyone is interested.

    In the meantime, I will briefly talk about the UKSC itself. This is a monoblock computer where a keyboard is built into the case. In the 80s, when the UCSC was developing it was a standard solution for home PCs, you just need to recall the ZX-Spectrum, Amiga, Commodore, MSX and all other “well-fed keyboards with a processor inside”.

    And now I will not tire the venerable audience with sheets of text and begin to upload photos.



    My copy of the UKSC is in pretty good condition for his age. This is a student model with a 42V 50 Hz power supply unit released in 1990 at the Kvant plant.

    Despite the fact that the computer is almost 30 years old - it works.

    A feature of the student model is a 42V PSU according to the rules of electrical safety and a DC + DC converter not soldered to save DC-DC +5 then ± 12V to power the interface chips of the joint C2 port which is a direct electrical analogue of RS232 but with a Soviet connector and a different pinout.

    I have a laboratory transformer 220-36 / 42V and it allowed me to check the UKSC, but in modern conditions I consider its use not justified. It takes up a lot of space and buzzes quite loudly. For this reason, I decided to replace the power supply unit of the UKNTs with a small, modern industrial power supply unit.

    With an open external cover fastened with latches around the perimeter of the case, the UKNTs looks like this.



    The 42V PSU is pulsed, it gives out + 5V 2A and this is enough to power not only the UKNTs itself, but also expansion cartridges that are installed in 2 slots on the right side of the board.
    I myself saw a ROM cassette with Vilnius BASIC, a drive controller, an IDE HDD controller, a 512 KB RAM disk.

    Here is a close-up photo of a board with a power connector.


    The “+” sign marked + 5V, the “-” sign noted GND.

    There are 5 holes next to the board-free section of the board - 2 in one row closer to the keyboard and 3 closer to the power connector. This is a seat for installing a DC-DC converter for powering interface C2 interface chips. While ± 12V power is not supplied to them, nothing can be connected to the COM port.


    A few details about the blue connectors facing the rear panel of the case.

    The short blue connector near the power supply, the Russian version of the IDC10 with latches is Joint C2, the same COM port. Next to it, the wide blue analogue of IDC40 is a programmable parallel port made on a large black chip KR580VV55A - it is freely programmable and can work not only as an analogue of LPT, but even as an external bus for exchanging equipment, it all depends on the driver. The remaining two IDC10s are connected to the monitor outputs in parallel - RGB + SYNC signals + composite video + sound beeper and, of course, ground. The last DIN5 is a tape recorder port through which you can play audio tapes of programs with programs from the MP3 player, loading the computer, or solder the cords to the PC audio card and load-unload in both directions. And finally, the button is hard reset. If everything hangs tightly, we boldly look forward to it.

    And here is a photo of the rest of the board, if you remove the keyboard.


    The large blue connector below the power supply is actually an adapter dressed in lamellas of the edge connector that implements the MPI bus adopted in Soviet systems as an analog of Q-BUS DEC. The bus is 16-bit multiplexed, data and addresses are transmitted on the same time-division lines. At the second end of the “extension cord" you can see the edge of the "LAN" board.

    The local network of the UKSC is built according to the architecture of the ring bus on the chip 1801VP1-065 that implements the interface Ctyk C2 operating at a given speed of 57600.

    In addition, two 1801VM2 processors are visible on the UKNTs board, KA1515XM matrix logic chips are analogs of once programmed at the FPGA factory that implement the “chipset”, standard 1801VP1-xxx alternative chips, ROM and 565RU5 RAM, fine logic and good old green KM- in places ki causing drooling of stupid and greedy huckster metallers, they also have tantalum!

    According to the classical architecture of the DEC PDP-11 mini-computer, the UCNC was designed as a “terminal machine”, a central processor with its own memory and a “terminal” connected to it according to the standard register 177560. That is why two identical 1801BM2 processors are located on the motherboard. On the actual board there are 2 computers working independently most of the time. The main (Central Processor) - on its 1801BM2 processor and with its 56kb memory, is a “terminal machine” architecturally similar to LSI-11/03 which through a register in memory can work with any terminal, standardly with a teletype or terminal via RS-232C. And the second 1801ВМ2 (Peripheral Processor) with its 32 kb memory which works as a terminal,

    The second processor serves the keyboard, the video monitor has 3 banks of 32 KB each, I / O ports, loads the system and implements the “console” mode for debugging and controlling the central processor. Yes, you heard right, at any time you can stop the program execution of the main processor and use your hands to browse, edit the memory, and then start the program again. Moreover, you can run your own separate program on the second processor of the “built-in terminal”, when the “main processor” is busy with its task, the terminal has 22 kb of free memory.

    But let's return from the wilds of the DEC architecture in the Soviet version to our history - to replace the power supply.

    Here is his photo.


    The power wire with a connector from the old PSU was soldered, the red wire is + 5V, the blue wire is GND.


    Power terminals for 220 and output ± 5 and + 12V.


    A plate with voltages and currents on different channels of the power supply.


    The power supply perfectly sat in the place of the old one after I had to break out the screw mounts and bite a couple of small reinforcement ribs. The power supply does not hang out, I also connected a red LED with a current-limiting resistor of 2.8 kOhm to indicate the operation of the PSU on the + 12V channel. But the power supply tightly takes up space inside the case and does not allow you to put the power button in its native place, so for now - turn on / off only with a plug in the socket. This is certainly better than the native PSU and the hefty buzzing box of the step-down transformer nearby.
    Now I'm waiting for a parcel with a ± 12V imported converter to come from Chip & Dip, the Soviet one is no longer possible to find and I don’t know its brand. So I'm waiting for the EGA-CGA-RGB to VGA GBS-8220 converter to come from China to connect my UKSC to a modern monitor. My old small monitor MS 6105.02 cannot catch the synchronization with the UKSC and the image floats as it is not regulated.

    There are also plans to buy a combined FDD + IDE-CF controller for which a drive emulator has already been purchased that allows USB sticks to connect DSK floppy disk images with programs for the UKSC and run the RT-11 OS. In the future, a CF card with created 32 MB partitions for RT-11 disks will be connected, which does not understand partitions of more than 65535 blocks of 512 bytes and the system will start “from the HDD”.

    So far, the seller of controllers has some difficulties with the purchase of components for assembly and we must wait. When the converter arrives at the monitor, there will be a continuation of the article about connecting the UKSC to the VGA monitor. When there will be a disk controller - an article about connecting them and launching the OS.

    Everyone who worked with UKNTS, DVK, Electronics-60, SM-4, SM-1420 with these DEC PDP-11 / LSI-11 / VAX-11 - write, comment, share experiences, remember youth as I do.

    Good luck to everyone, see you all!

    The second part of the story

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