34

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-...


30

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 ...


18

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 ...


16

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, ...


16

As others have mentioned, “Program too big to fit in memory” means that DOS can’t find a large enough memory block to fit the amount of memory that your program’s header requests. This can be either because you have too little available conventional memory (extended memory isn’t taken into account), or because your executable is corrupted. To answer your ...


9

Yes, there was at least one serious attempt to identify them, by Sergei Skorobogatov, who wrote an article about that: "Searching traps in Zilog Z80 CPU" back in 2014. I don't know if I have permission to replicate the complete article here, as this would be the ideal case for a complete answer. In the meanwhile, his efforts can be read here: https://www....


9

The simplest way to patch a .com file is DEBUG, which comes with any DOS installation. DEBUG is partially usable for .exe files as well, but cannot reverse their relocation process, and so cannot save them once they have been relocated (If you load them as a plain binary file instead of an executable, you can, however, save them, but have limitations with ...


8

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 ...


8

a bit off topic to your actual question but to make your game/exe whatever usable again: Too much memory common on MS-DOS for 32MByte and 64MByte (IIRC some versions use 32 some 64). The memory manager reports negative value of free or total memory causing this problem. To repair simply use Smart Drive and fill memory to it until only 32MByte or slightly ...


7

Z80 has been implemented in the Visual6502 way too. However looks like the site http://www.micrologo.net/z80x is no longer operational. It was Z80 die simulation in Javascript When I searched matching stuff from mine off-line copy I found this repository: Visual6502 Z80 chipsim So if you want to run the Z80 simulation download the repo and open expert-z80....


6

Back in the day, MacNosy was the go to disassembler tool to attack things like that. He also wrote a debugger. I can't speak to its status today. Apparently the web site still exists: https://www.jasik.com (We are talking 68K code, right?)


5

The IMG.* files contains all textures and sprites in uncompressed/unencrypted state so its very easy to render, but there is no VGA palette there (nor in other files you posted). I found this: Nightmare3D DOS Archive and inside the game zip I found GAME.PAL file containing the palette ... Its 1924 Bytes long and its look like the palette for IMG.* sprites ...


5

I don't know if any TurboGrafX16 games suffered from this problem, but they were not fundamentally immune. Any game pushing the limits of a console in this era could have lag frames, even if the limits are higher. A bug could cause it even in a game that doesn't come anywhere near to pushing the limits. A NES with a faster CPU could potentially fix the lag ...


4

The state of the art in assembly-level debugging of DOS programs is almost certainly SoftICE. I've never used it, but my understanding is that it was for a very long time the tool of choice of software copyright protection scheme crackers, as well as low-level operating system/device driver developers. That said, it may well be overkill for your problem. ...


4

The HuC6280 used an instruction set and architecture which was largely identical to the 65C02 -- each instruction is represented by a one-byte opcode, followed by up to three bytes of immediate data. The amount of immediate data is implied by the opcode. (The flags are a CPU register, not part of an instruction.) The HuC6280 appears to support all ...


4

The processor is a modified 6502 so one word is 8 bits. Many instructions are encoded as multiple words but for those the processor just fetches them in sequence when required. I believe the graphics processors use a wider bus, hence the '16' part of the name.


3

The best I've seen is Goran Devic's implementation for an FPGA. He's taken the existing bits of Z-80 reverse engineering and filled in the missing pieces and connected them all together. Read through the blog and you'll find a large PNG functional diagram and a link to a bitbucket repo of all the code. Although I haven't done a deep dive into the details, ...


3

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, ...


3

Technically, the most up to date modern fork of otx is being maintained by Zhi-Wei Cai on GitHub here. v1.7: Build 566 or a fresh clone of master should work on any modern OS X system. But that's not why we're here. This is Retrocomputing Stack Exchange after all. The most recent fork of otx which works on legacy OS X platforms is probably the linuxaged ...


3

Yes, all machines of the era could have this kind of lag frame. The issue here is that under certain very specific circumstances the Nintendo console can't finish all the processing it needs to do in one frame. Normally the game limits the amount of processing to be done so that it all finishes in one frame, but if a particular glitch used in speed running (...


3

I have an old game I would like to run, but my DOS machine has too much RAM. The most proper way to run DOS applications in Windows is using DOSbox. "Program too big to fit in memory" It may happen that you have corrupt executable. Obviously I would want to be able to have basic debugging functionality as well, breakpoints, watchpoints, etc. In ...


2

You might be able to find the precise dimensions in the Developer Note that came out around the time of the release; this is what would also have pinouts and specs for RAM expansion and so on. You'll need to do a little more than just repackage some modern cells and get the right voltage and wattage, however: The PowerBook will try to charge the battery ...


2

While the Jasik Debugger is probably the most capable tool, and appears to still be available for purchase, there is also TMON. TMON has more capability than MacBugs, and is designed to explore the structure of memory and executing programs. It also seems to provide hints on parameters for system calls used by the program, making the code potentially much ...


1

Read and extract SND.DAT Code is C# but is easy enough to understand and port to another language. Basically there are 6 bytes entries that tells where is what in the file, some of them are dummy. I have already identified for you the different types of files in it: IBK MID VOC Winamp will play MIDI files out of the box. VLC will play VOC files ...


1

I remember MacsBug as a System wide debugger "INIT". It could be activated by pressing the NMI-Button on the programmer's switch on real hardware (or else by keyboard with Cmd-PowerOn, if I remember right). See Wikipedia for details.1


1

The Soviet system was a system of administrative competition. What and how to copy, was decided during the interaction of groups of influence. Personal factor mattered. The x86 and Zilog architectures did not have significant support in Moscow (where they loved PDP-11) and were copied out of need and a residual principle. There were several ministries (prone ...


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