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1500 questions
20
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3 answers
How did the Altair 8800 front panel load the program counter?
My understanding is that when you toggle in an address on the Altair 8800 front panel switches and then press the EXAMINE switch, it loads the program counter with that address, or at any rate does something so that you can then press SINGLE STEP or…
cjs
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20
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Change Amiga Shell keyboard layout in Workbench 1.3
I'm using Workbench 1.3 in Amiga 500.
I managed to change the Spanish keyboard in "SetMap", as shown in the following figure:
And I can write text with special spanish characters (ñ,ç,ó,á,...) from regular application like NotePad:
But when I try…
ManuParra
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20
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Why was the Sega Genesis marketed as a 16-bit console?
The Sega Genesis / Mega Drive's main CPU, the Motorola 68000, was a 32-bit processor. Couldn't Sega have marketed the console as a 32-bit device? Or is there a technical distinction about how the 68000 was used in the Genesis that makes the system,…
Joe Sewell
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19
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3 answers
When did hardware antialiasing start being available?
An important step towards 3D gaming was the ability to scale sprites or tiles by nonintegral factors. Examples of the former from the eighties were the arcade games Pole Position, Outrun, Space Harrier and Afterburner; a subsequent example of the…
rwallace
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19
votes
4 answers
Why did the Cray-1 have 8 parity bits per word?
According to https://en.wikipedia.org/wiki/Cray-1
The Cray-1 was built as a 64-bit system, a departure from the 7600/6600, which were 60-bit machines (a change was also planned for the 8600). Addressing was 24-bit, with a maximum of 1,048,576…
rwallace
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19
votes
1 answer
Did 5.25" floppies undergo a change in magnetic coating?
3.5" floppy disks, in the transition from 720K to 1.44M, changed the actual coating to a different compound that was magnetically 'stiffer'. This was necessary to support the higher density, but meant the old disks could not support the new…
rwallace
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19
votes
2 answers
Examples of operating systems using hardware task switching of x86 CPUs
Intel IA-32 architecture a.k.a. x86 offers hardware task switching capabilities since 80386. It includes TR (task register), memory segmentation features such as Task State Segment, task gates, call gates etc. However, this capability is not used in…
Grigory Rechistov
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19
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3 answers
How to use the "darker" CGA palette using x86 Assembly?
For those of you retro developers out there, I am having a hard time figuring out how exactly to select the "darker" color palette in 320x200 CGA mode. Here's what I have so far:
setup_cga_graphics:
mov ah, 0 ; int 10,0
mov …
JohnnyStarr
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19
votes
4 answers
Is there a line printer sound simulator?
To improve "authenticity" of a mainframe simulator and for an additional nostalgic effect, I'd like to add sounds of a line printer to it. They should be similar enough to the original sounds for people to recognize familiar cadences of standard…
Leo B.
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19
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Unlicensed home computer ports of arcade games
During the 1980s, it was quite common to see unofficial ports of popular arcade games released on home computer systems. For instance, Acornsoft (the software division of Acorn Computers) released many titles that were clearly unofficial ports…
pmarflee
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19
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2 answers
What is the danger involved in trying to write already closed file with Commodore 1541 disk drive?
The Commodore 1541 disk drive and other IEC devices are self-contained computers. The operating system runs on the drive itself. This setup significantly improves the flexibility. As a side effect, if there is an error during a disk operation, the…
wizofwor
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19
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1 answer
Where does the hierarchical directory structure originate from?
Windows, Macintosh, Unix/Linux: today, they all support a hierarchical directory structure. The differences are in the details (mount points vs drive letters), but all use a hierarchical directory structure.
The accepted answer to question Is there…
juhist
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4 answers
Why did the TI-99/4 have two databuses?
Wikipedia says on Russian page:
Однако к 16-разрядной шине были подключены только 256 байт статической памяти и системное ПЗУ. Остальная память (ОЗУ) и периферийные устройства были 8-разрядными и подключались через мультиплексор, что требовало…
Omar and Lorraine
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19
votes
3 answers
Can a Commodore 64 use two screen modes on one scanline?
Many games, for example, Maniac Mansion, or Kissenschlacht, use two screen modes. Oftentimes, a bitmap mode for the main screen, and a text mode for the lower part which displays scores or whatever. Considering how the raster moves across the…
Omar and Lorraine
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19
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4 answers
Why did the Atari 5200 forsake compatibility with 400/800 game cartridges?
The Atari 400/800 home computers were well-established and quite successful in the games market by the time the Atari 5200 console was released in 1982. The 5200 shared the chips and architecture of the 400/800, and it appears on the surface that it…
Brian H
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