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42 votes
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How were Western computer chips reverse-engineered in USSR?

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 ...
Algimantas's user avatar
  • 1,344
37 votes

How were Western computer chips reverse-engineered in USSR?

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 ...
Igor Skochinsky's user avatar
24 votes

How were Western computer chips reverse-engineered in USSR?

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 ...
noop's user avatar
  • 341
22 votes

Do people fix software bugs in old arcade games?

Yes they do, for example see this list which mentions Defender bugfixes for example. Don Hodges has done quite a few.
Alan B's user avatar
  • 4,620
21 votes
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What tools were used in late MS-DOS era for reverse engineering and patching binary executables?

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 ...
Stephen Kitt's user avatar
19 votes

How were Western computer chips reverse-engineered in USSR?

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. (...
tofro's user avatar
  • 35k
18 votes

In the original Z80 layout, where are the "traps" located? And what are their effects?

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 ...
mcleod_ideafix's user avatar
18 votes

What information was "off limits" to IBM PC clone BIOS authors?

Apparently, US law allows analysis of an implementation as a base for a clean-room implementation, as long as the analysis and the implementation is done by separate teams that are only exchanging ...
tofro's user avatar
  • 35k
18 votes

Is there a common name for this 'switch' like 6800 assembly routine?

The term that comes to mind is "dispatch table". This is a table containing pointers to functions, one of which will be chosen based on an index that has been provided or gets calculated. ...
Walter Mitty's user avatar
  • 6,158
15 votes

How can I reverse-engineer the game Wizardry (1981) for PC, based on UCSD Pascal?

A few hints about how the UCSD system works. What's often called UCSD-Pascal is in fact a stand alone OS with Pascal as one possible language. Others were BASIC, FORTRAN, Ada or Assembler. The whole ...
Raffzahn's user avatar
  • 224k
14 votes

How can I reverse-engineer the game Wizardry (1981) for PC, based on UCSD Pascal?

The background has already been explained, some additional details. I don't know where to get the version you have, but quick googling found a version with a 320K WIZ1.DSK. This one clearly is a UCSD-...
dirkt's user avatar
  • 27.9k
14 votes

Do people fix software bugs in old arcade games?

Some MAME cheats allow fixing bugs. A few examples: the infamous Pacman split screen Donkey Kong level 22 premature timeout Probably a lot more examples. The MAME Cheats database is a good way to ...
Jean-François Fabre's user avatar
13 votes

What tools were used in late MS-DOS era for reverse engineering and patching binary executables?

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 ...
tofro's user avatar
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13 votes
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Did Digital Research clean-room MS-DOS?

Short Answer Sort of. Digital Research had two teams, in different countries, that developed the product that became DR-DOS in two stages. The company that purchased DR-DOS only claimed in court that ...
Davislor's user avatar
  • 8,745
13 votes
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How can I make the Microsoft C compiler for DOS emit a loop with an intermediate jump to continue?

It turns out that in MS C 5.1, in addition to all the /O... options there is one seemingly unrelated one that influences the optimizations for this compiler: /Zi. In the output of CL /help it is ...
neuviemeporte's user avatar
12 votes
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Reverse engineering an RS-422 protocol with access to only one device?

I posted a comment on the reverse-engineering Q&A you linked before I realized it'd do better as an answer here. The answerer there found that googling Accom and Axial from your photo turns up a ...
ssokolow's user avatar
  • 7,065
12 votes

How can I reverse-engineer the game Wizardry (1981) for PC, based on UCSD Pascal?

What an intriguing piece of archaeology you've stumbled upon! COM programs, present an interesting quirk. Despite its code segment being confined to a mere 64KB, they allocated all available free RAM ...
Rui F Ribeiro's user avatar
11 votes
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Dump process memory of Windows 3.1 control panel applet

Among the Borland Pascal 7 example programs, there is an OWL application called HeapSpy, which can inspect the list of memory blocks allocated by any running Windows module. The demo is pretty ...
user3840170's user avatar
  • 23.2k
11 votes

How are Amiga Kickstart Relocation Files (.RTB) created?

The job is non-trivial, but I don't think it would be hard for someone 'experienced in the art'. 256k or even 512k is not a lot of code, and the ROMs are highly structured with a well-defined ...
Bruce Abbott's user avatar
  • 6,693
10 votes

How were Western computer chips reverse-engineered in USSR?

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. ...
Nick Bailuc's user avatar
9 votes

What is known about the internal workings of the Z80?

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 ...
Spektre's user avatar
  • 7,276
9 votes

What tools were used in late MS-DOS era for reverse engineering and patching binary executables?

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 ...
Spektre's user avatar
  • 7,276
8 votes
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How are Amiga Kickstart Relocation Files (.RTB) created?

I finally had to bite the bullet and do the exercise to create a .RTB of a ROM file which didn't have one: the old A1000 1.1 ROM (v31.34) Bruce Abott answer is spot on on most parts, but devil is in ...
Jean-François Fabre's user avatar
8 votes

How can I extract game data from Nitemare 3D files?

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: ...
Spektre's user avatar
  • 7,276
8 votes
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How can I debug a Mac OS Classic application?

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....
Will Hartung's user avatar
  • 12.3k
8 votes

Is there a common name for this 'switch' like 6800 assembly routine?

Is there a common name for this 'switch' like 6800 assembly routine? No. There is no specific name for exactly this technique. In fact, even generic names vary depending on whom to ask. I do need to ...
Raffzahn's user avatar
  • 224k
7 votes

What tools were used in late MS-DOS era for reverse engineering and patching binary executables?

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 ...
Jules's user avatar
  • 12.9k
6 votes

How were Western computer chips reverse-engineered in USSR?

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 ...
Raffzahn's user avatar
  • 224k
6 votes
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Is otx (Object Tool Extended) still actively being maintained for reverse engineering legacy OS X binaries?

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 ...
JAL's user avatar
  • 9,520

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