Little is known about how these computers and chips were made, because their development was top secret in the Soviet Union.
As far as I know, Soviet Western-compatible ICs were made by copying masks used in fabrication or by buying manufactured products under fake identities and smuggling them back into Socialist countries where they were reverse-...
These were probably the Setun computers, built in the Soviet Union between 1959 and 1965. It used balanced ternary (with the digits 1, 0, and -1) for computations, and a three-valued logic (I haven't been able to find which one) for operations. Electrically, it almost certainly used "ground", "positive voltage", and "negative voltage" as its signaling ...
It seems to be pretty much accepted wisdom that the Soviets completely cloned the Western chips and did not simply develop reimplementations of the same instruction sets. Since at the time it was pretty important to have the impression of having own developments, the copying was obviously not admitted publicly so not much is known about how exactly the ...
This answer is written from memory, corrections may be made later if I remember/research more details. It starts with historical background to put things into perspective. This answer is specifically about Soviet ZX Spectrum clones, for other stuff read other answers, or for example this https://www.glaver.org/blog/?p=959 (Yes, Soviets were copying ...
No need for any special Spectrum knowledge. It's about power, and there is no rectifying, no appropriate sized capacitor and voltage control elements on this board, so it most definitely does not take AC but rather some well regulated DC input. I'd assume 5V. So operating it at some arbitrary AC and higher voltage my fry it right away.
Usually the start ...
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 ...
You could reverse-engineer those early CPUs by grinding or etching away the top (plastic) layer of the chips down to the silicon die and examine the chip structures on an (optical) microscope.
(Picture of a real Z80 die, from Wikipedia, Von Pauli Rautakorpi - Eigenes Werk, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=30690133)
The Z80 had, ...
Looking at the linked schematic and the photo of the internals, I'd say the ports are the following (listed from the reset switch over)
Composite video (or possibly monochrome luma only)
The port with the two thicker wires is almost certainly the power, as you identified, backed up by the "upside-down T" symbol on the ...
After pressing "AP2+CБP" key combination computer switches to extended memory mode, in which screen is reduced to 1/4 of original size giving about 12Kb memory of screen RAM to user (extending user RAM from 16K to 28K).
As already said (in the comments) it will take more than just a few interviews to get an idea why. It's the crux of this kind of questions as there is rarely a definitive answer. Looking at the timeframe, it seems obvious: The time for a mass marketed, simple 8-bit system designed in 1982 had passed by 1991
But why was it withdrawn from the UK market so ...
Only you can decide which port is which as you are the only one with access to your HW. I would use multi-meter and or short circuit tester:
I see no stabilisator nor DC/DC nor AC/DC converters so the power supply is external. Here is first Z80 pinout image I found in Google you can check against any Z80 datasheet.
It is look from top side ...
In the USSR, the analog TV sets used SECAM, not PAL, so I imagine that the timings will be different between the UK Spectrums and the Leningrad.
SECAM is, like PAL just the colour encoding and on top of the basic B&W TV signal. Basic timing is therefore not touched. It's just about how colours are put ontop - which is done in the modulator circuit anway,...
Computer development wasn't necessarily "top secret" as is commonly said about anything that has to do with the Soviet Union. The engineers there used the same methods as other companies in Taiwan. Z80 is probably the most cloned CPU, because of its popularity and therefore wide compatibility.
Access to these computers weren't limited to "spies who ...
No sign of the actual game but found a mention of it in the "besm6" mailing list:
It was based on a BASIC game, publishes in the '70s in a magazine such as BYTE (or Datamation).
I my time I've read such magazines in ГПНТБ(Russian National Public Library for Science and Technology), and ...
A post to /r/tipofmyjoystick has brought the answer virtually instantaneously: the original game is Inspector Clew-So; other locations, some including the plaintext source can be found by searching for CLEWSO.BAS, for example, https://archive.org/details/riag_006_Volume_244_-_Games
The game I remember was slightly modified compared to the original: apart ...
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 ...
КР1858ВМ3 used 2μm lithography unlike the earlier variants using 4μm
Т34ВМ1 and КР1858ВМ1 were both based on U880 masks, while for КР1858ВМ3 the manufacturer seems to have designed an original topology. The irony is, КР1858ВМ3 had a larger physical chip size despite 2μm lithography.
Т34ВМ1 was considered as experimental series produced ...
Leningrad is a primitive and not particularly compatible clone. However, it is pragmatic, so the incompatibilities are not always going to show up. The main differences are due to a completely different way in which timings are implemented in Leningrad, to an extent that I would not personally call Leningrad's circuitry "an ULA clone". I am a coder, so I can ...
Well this certainly isn't exhaustive, but from what I can see the answer is no.
I still find it fascinating that the Soviet basic school computer was a PDP-11 in a micro format. It makes me wonder what our systems of the era would have been like given a similar CPU. In any event, this is also a rather limiting factor. Porting MS BASIC from one 8-bit ...
Computer "Composit" (Leningrad+).
Left to right:
+5V 0.6 Ampers
+5 Volts, 1 Amper
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 ...
Given that the clock part in the Электроника ИМ series, according to the wiki page, was not modified to support the customary in the USSR 24-hour mode, it is likely that there was no electronic design whatsoever, and the only thing that was designed anew were the new game scenarios and the new LCD panels that could be supported by the existing underlying ...
At least, KP1858BM1 and KP1858BM3 are completely different designs, starting from the fact that BM1 is NMOS and BM3 is CMOS.
Also it is known that BM3 differs in execution of HALT command: while the original Z80, whether it is NMOS or CMOS, makes idle M1 opcode fetches during HALT (thus supporting DRAM refresh), BM3 simply ceases all activity. As the ...
Definitely not. Vilnius Basic was created specifically for the 16bit K1801BMx chip family, and by and large was a port of MSX Basic for this CPU.
Porting it to 8-bit machines was impractical due to widespread clones (or should I say adaptations, because they typically included extra functionality such as graphics or music)
of MS Basic 3.2.
From this page - It is in a section focused on BK0011, but symptoms are very similar:
It really had 32KB RAM onboard but by pressing the 'Expanded memory' button you could send it to the mode when only 4 lines of text were displayed on a screen, and saved video RAM was added to available memory.
I guess it could have the same reason (memory allocation ...
First of all: Wow, nice exchange. A fun piece for a museum. Where is it located?
I am sorry, if this is not a good place to ask,
Not really, as your question seems to be about electronics and scrap metal, not old computers.
but is there any general rule of thumb about how much precious metals could you expect to get out from 197x(?) printed circuit ...
So I solved it. You can set different monitor options when running programs using the "multiplexer" switches. When set to 0 (as I had it), you see the output of the
К1804ВУ1 chip (ie data going into memory). If you set the multiplexer to 1, you see data coming out of the К1804ВС1 (ie after logical operations).
Also I should say that the different sets of ...
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 ...
How were these chips made? Could they have possibly taken a Western chip and taken it apart somehow, to manually build a netlist, as was recently done to the 6502? Or was someone able to procure the masks from Zilog's and Sinclair's engineers?
Yes, yes and yes.
It's been a rather complex mixture of spying, buying and hard core reverse engineering. Also, ...
In 1991 places buying 8-bit machines were decidedly not the UK or "the west" in general. In contrast, this was precisely when Atari found a new life in Poland.
So I suspect the basic story here is that they introduced this machine in the fSov block because those people were still buying them - largely due to exchange rates I'd guess. And then someone in the ...