Brian H
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For TRS-80 Color Computer joystick buttons, is it correct to check the first or second bit of the value at PEEK(65280)?
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4 votes

Address 65280 (Hex &FF00) is the I/O port on the CoCo for the joystick and the keyboard row input. It is the case that the lower 2 bits are assigned to the left and right joystick buttons. Bit 7 ...

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Could Apple II cards be used on any 6502 platform?
1 votes

I believe the major factors, besides just the electrical characteristics of the bus, are: Standardization of access to each slot, such that each is guaranteed certain resources that cannot conflict ...

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The Sentinel (aka The Sentry) on Commodore 64 - why was scrolling so fast?
3 votes

There are two essential elements to programming such smooth scrolling on the C64: Use C64 hardware scrolling, which can move the screen in single pixel increments, but only for 8 pixels. Use double ...

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Is it possible in Commodore BASIC V2.0 to configure the system so that the PRINT command does not update color?
2 votes

The "problem" with a screen text rendering routine that also sets the color of each character cell it outputs is performance. It requires two writes for each character, but only one is required if you ...

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What is the largest RAM expansion for Amiga or Commodore?
7 votes

Big box Amigas (A3000/A4000) with Zorro-III 32-bit bus can accommodate 256MB RAM expansion cards, which are still being manufactured today. Utilizing 4 Zorro-III slots, this allows memory expansion of ...

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Were the custom chips in the Amiga exploited for their hardware bugs like the ones in the C64 and Atari 8 bit computers were?
26 votes

The Amiga OCS was not exploited in the same way as the C64's VIC-II simply because the OCS was designed from the beginning to support rapidly changing video output modes. Unlike the C64, and most 8-...

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What sort of RAM chips did the Commodore 64 use in 1994?
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12 votes

The highest capacity DRAM to ever be used for the Commodore 64 motherboard was 256Kbit. By the early 1990s, 1Mbit DRAM was commonplace, but used in a 256Kbx4 would require the C64 to have 256KB of ...

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How to backup/dump Atari 520st floppy disks on modern hardware
3 votes

I have always gotten good results with ImageDisk (IMD) running on a retro PC under MS-DOS. You need a machine that has a compatible floppy controller, which most of the PC's from the 1980s and 1990s ...

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Why did certain color combinations look terrible on the Commodore 64?
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14 votes

This is just the well-known "AEC Glitch" of the C64's video output, exacerbated by the additional analog distortion of the RF output to a TV. Anyone who used a C64 on any kind of display is familiar ...

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Could monochrome systems produce better output for monitors than TV sets?
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7 votes

RF encoding introduces significant noise to the video signal because it moves the signal up to an area of the spectrum that is much more susceptible to interference. A monochrome 240p video signal of ...

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Were Mac systems faster than Windows in processing performance?
4 votes

The users' perception of "processing performance" on Macs vs. Windows PCs is likely influenced by 3 unmentioned differentiators: The relative performance of all versions of MacOS (macOS) vs. all the ...

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Are there statements from IBM insiders revealing why OS/2 was dropped?
3 votes

I think that your question does not give quite enough credit to Microsoft, and the competitive advantage they established over OS/2 by making the Win32 API a common feature of both Windows 9x and ...

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Did any computer allow overscan on a CRT monitor?
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19 votes

The Commodore Amiga (all models) had hardware support for overscan on CRTs. This was accessible to the user through the Preferences settings, as shown in the dialog panel below. The Preferences ...

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8 registers in the 9440?
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5 votes

Looking over the data sheet referenced, there is also an Instruction Register, and a "Bus Register". The IR is obvious. The BR seems to perform a similar function for fetched data (not instructions). ...

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Did any significant programs or environments take advantage of the Rexx language which came with PC DOS 7 (aka PC DOS 2000)?
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13 votes

The answer is a resounding no. Rexx was not a popular scripting language for DOS because it didn't offer any significant advantage over DOS batch files, besides the differing syntax which is a ...

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What are the differences between the various HxC Floppy Emulator hardware options when used with an Apple II?
2 votes

The HxC/Gotek floppy emulators are designed to work with a Shugart type floppy interface, which was widely used in many retro-computers, but is not directly compatible with the Apple ][ floppy ...

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What is the exact bus protocol used by the C64/C128 REU?
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12 votes

The basic behavior is correctly stated in the question. However, the details of the timing have to account for the rather complicated details of how RDY works on the NMOS version 6502 and MOS 6510 (...

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Why does the single dot entry exist in file systems?
-3 votes

The contrarian view is that the use of "." to represent the current directory is not a necessary feature, and is not really a "feature" at all. Rather, it is a legacy of unsophisticated command-line ...

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Was OS/2 a viable alternative for daily DOS and Windows tasks?
9 votes

I recently installed OS/2 Warp on a vintage (late-90s) IBM PC 350 with a 200 MHz Pentium MMX CPU and 96MB of RAM. I found that OS/2 Warp works very well for running virtually any DOS or Windows 3.x ...

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MOS 8502, just a 6510B?
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23 votes

The change in the MOS designator from 65xx to 85xx was due to the process change - original 65xx were NMOS process, while later 85xx changed to the new HMOS process. This allowed for better densities ...

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Which cartridges were typically used together on Commodore 64 systems?
5 votes

The most common usage for an expansion bus extender was to simply eliminate the wear-and-tear on the computer's expansion connector from frequently swapping cartridges in and out. Instead, the ...

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What's the difference between an IBM 5153 (CGA) CRT picture tube and a color TV picture tube?
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5 votes

If you took all the electronics from a monitor like the IBM 5153 and substituted just the picture tube from a color TV, what would still be lacking in terms of display quality? The answer to your ...

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Mac SE tube won't come on?
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4 votes

Without any other information, my first likely response has to be for you to verify the reassembly. Since I don't know what you actually took apart/disconnected, any errors made putting it back the ...

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How to connect a Tandy Color Computer to a Composite Monitor?
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12 votes

The TRS-80 Color Computer 1 and Color Computer 2 only supported RF output to a TV. It wasn't until the CoCo 3 that both composite and RGB output were added - RGB being essential for the new 80-column ...

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What was the intention with the Commodore 128?
31 votes

The Commodore 128 was intended to be a fully-compatible, more professional, upgrade to the popular Commodore 64. The marketing called for addressing the most widely criticized shortcomings of the C64 ...

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What are the Ultra-Highres registers in ECS and AGA for?
1 votes

I think you are not taking into account both of the new video modes supported by the Amiga ECS chipset using the higher dot clock: Super-Hires Mode: 1280 pixel horizontal resolution, interlaced or ...

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Non-obvious compatibility of M1297 monitor
0 votes

While the M1297 is an excellent quality Trinitron CRT, it will be quite difficult to use it with anything other than the various color Macintosh systems for which it was designed. The main issue is ...

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Why did computer video outputs go from digital to analog, then back to digital?
35 votes

Early digital video outputs, like CGA, were not really akin to the later standards such as DVI and its follow-on's. The reason for using multiple lines to carry the different analog portions of the ...

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Term “console” in game consoles
15 votes

The use of the term "console" in reference to home video game systems arose because of the association of these systems with TV's in the U.S. At the time these systems were gaining popular acceptance ...

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Understanding C64 Character Memory
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10 votes

"Character memory" is the bitmapped definitions for each of the characters (e.g. "glyphs") that are displayed in text mode, based on the "character codes" that are poked into the "screen memory". ...

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