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67

There were a few reasons: Old monitors had very low refresh rates (driven by hardware prices), and green phosphor has the longest afterglow (remains on the screen for the longest time) Green phosphor was the first available for use in monitors (and some sources also say that monitors of this type were physically lighter) It was the brightest type of ...


35

CRTs don't have pixels, they don't work that way. Also, arcade monitors expose all the picture controls at the back so it is possible to adjust them quite extensively. Operators would have made sure that the picture was the right shape and in focus near the edges. Since the controls are all analogue and no-one bothered to measure the display geometry the ...


33

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 signal to the monitor was to prevent crosstalk interference of these signals. You can see this in the very early computers like the Commodore 64 and Atari 800 ...


31

CRT TVs are analog devices, there is no "pixel", but the size of the spot limits the resolution of the image, as the size of silver nitrate crystals limits the resolution of photo films. Several arrangements of the colour stripes on the CRT tubes have been designed, they are a compromise between resolution, luminosity and the precise alignment of the ...


25

VGA's 640x480 mode was the first to offer square pixels and an exception among all VGA modes available (320x200, 640x200, 640x350 and 720x400 for Text). Square pixels weren't the standard back then. Adding video modes in later (Super) VGA was kind of a marketing game to offer higher numbers to outpace competition. First it was Colour, like offering 640x480 ...


24

ZX Spectrum: has 21 user definable graphics (UDG) available to the user via POKE USR command. Also, main character set can be redirected to RAM (sysvar CHARS, 23606-23607) so it is fully definibled. It doesn't have a real text mode. All text is rendered into pixels by the firmware. Jupiter ACE: has the entire character set in dedicated RAM (but available in ...


23

EHB For example, a game that uses EHB (Extra HalfBrite) mode during the game action (i. e. ingame) is Pinball Dreams. In my example run of the Beat Box table I can find the following in the copper list: $00D6EA WAIT $4211FFFE $00D6EE MOVE #$6200,BPLCON0 I. e. it waits for raster line $42 (66) and uses BPLCON0 to set the number of bitplanes to 6 without ...


23

Why did the original Apple //e have two sets of inverse uppercase characters? Simple: To allow lower case inverse letters. It's all about the clever way Woz arranged the original II's single character set to save in hardware and offer additional functionality. There is only a single character set of 64 characters, showing up 4 times in 256 entry character ...


21

Before VGA was invented, CGA RGBI used 4 wires to get 16 colors and EGA used 6 wires to get 64 colors on the cable. Add 3 more for sync signals and signal ground, and this won't be an issue, simple cables and connectors exist for getting EGA's about 16.3 million pixels per second digital signals over to the monitor easily. Amiga was released. It supports 4 ...


20

Digital Research produced as one of their early attempts into graphical desktops (on their way to GEM) a basic portable graphics library - GSX. GSX did actually support proportional fonts, both in print and on-screen, and was included with the CP/M support in Amstrad machines running CP/M Plus. GSX was supported by two of DR's own applications, DR Draw and ...


19

Yes, it is possible. There are a number of ways: If your TV has a SCART connector, you need a cable adapter from DIN 6 to SCART, wired like this (the audio is taken from the audio out using a standard stereo 3.5'' jack): (taken from CPCwiki) If your TV does not have SCART, but composite video input, you must Either use a RGB to CVBS adapter (using for ...


19

Was CP/M ever used, in practice rather than just as a tech demo, in less than 80 columns? Most prominent here may be the Apple II with Micro- Soft's Softcard. While most users did use it with an additional 80 column card, it also worked well using the basic 40 character display. After all, CP/M itself wasn't tied to any display size or a CRT at all. ...


19

Canonically in NTSC standards the drawn lines are tilted slightly so that the start of the odd field starting at the left is perfectly level with the top of the even field starting in the middle horizontally. The actual angle though is so tiny, ~0.09 degrees, that it's negligible compared to the rotation error you'd get just from the earth's magnetic field ...


19

Addressing the "why" part of the question - from my point of view as an assembly-code programmer on PDP-11 and VAX, the "standard" radix is most usefully chosen to match the instruction layout. PDP-11 had 8 registers and 8 operand-mode indicators. Its double-operand instruction layout was 1 bit generally byte/word indicator (b) 3 bits opcode (o) 3 bits ...


17

The 8080 is not a microcontroller, but a microprocessor, so it had no special provision for LCD displays, as modern microcontroller may have, except maybe for the ability to use packed BCD numbers. It had no in-built host peripherals that would support protocols like RS232 or SPI. You don't mention what kind of LCD display your college used, so this is only ...


17

The cheapest option is to use the composite output, so it's compatible with any monitor that supports composite but it's only black and white. Or if you have the A520 modulator (about $25 on eBay), you can get a color image through composite, RF (not recommended), or modify the A520 for S-Video. If your TV has a standard definition tuner, you may also be ...


15

Well Cromenco have something on page 2 of this issue of byte. https://archive.org/stream/byte-magazine-1980-11/1980_11_BYTE_05-11_High-Resolution_Graphics#page/n1/mode/2up 756x482 in 16 colors, and on page 70ish there's an article which talks about max raster screen resolutions of 1024x1024. Also worth looking at is the HP9845C with a cost of $39,500 ...


15

IIRC, the electron gun was actually installed in a position where it was rotated slightly relative to the tube, to compensate for this effect, so the scan lines did end up being horizontal.


14

Just the first (of many) example of using proportional fonts on Commodore64: https://youtu.be/k2NRlsopoOU?t=441 You couldn't really use a proportional font on the Spectrum because the colour attributes were one background and one foreground for each 8x8 square. That meant that, practically speaking, each letter had to be by itself in an 8x8 cell. ...


14

Did arcade monitors have same pixel aspect ratio as TV sets? Short answer: No, not necessarily. Long Answer: To start with, 'Title Safe Area' is an idea to define the parts of one transmission to be displayed even if any of the many receivers is maladjusted. It's nothing inherent to the TV signal or its definition, it's a safeguard against less than ...


14

The when and why of use of hexadecimal over octal representation is intimately tied in with where and what: the use of one over the other depended greatly on environmental factors, as well as the machine itself, with programmer preference mainly being developed by the influence of these. As Raffzahan points out, IBM 360 environments used hexadecimal from ...


13

There are a number of tools you can use to tweak the display mode, including setting it to 640×480. The Free Software for DOS site lists a few, of which I’ve successfully used VBEHz and Text Mode in the past. SVGATextMode, as mentioned by Radovan Garabik, would also allow you to configure your display in great detail. The 720×400 mode you’re seeing is ...


13

Prior to DEC's PDP-1, of 1959, there would be MIT's TX-2 of 1958 - after all, the PDP-1 (and DEC itself), was a spin off of this project (and team). That said, it was only a single machine and a research project, not anything commercial available. Before that, there was the SAGE system, operational in 1958, which was used for RADAR surveillance. Images from ...


12

It needs to be sync-on-green capable (any good monitor should have this mentioned in the specs). But even then you may have issues, I have a few O2's and I have observed that sometimes one of my monitors (Dell U2410, SOG capable) really distorts the colors (towards green), replugging the cable solves the issue. I had no issues with an Octane with 13W3->VGA ...


12

Maybe the most difficult task is to find a plug for the Apple AudioVision connector. Here is its pinout, taken from http://pinouts.ru/Video/audiovision_pinout.shtml , in case you find a suitable connector and want to do the wiring by yourself. 1 Analog audio ground 2 Audio input shield 3 Left channel audio input 4 Right channel audio input 5 Left ...


12

You're correct; the only interrupts on offer in a Vic-20 are those from a VIA — they're plain old 6522s in the Vic-20, not 6526s. The original VIC chip exposes the current scan line via a couple of registers so instead you'd perform a busy loop until it got to the number you wanted, then cue the VIA. I'm not a C64 expert but besides the lack of hardware ...


12

Yes there are a lot of compensations in a CRT like: magnets counteracting background magnetic fields circuits counteracting curvature of CRT screen surface circuits counteracting different length of the beam (edges/center) "linearizations" of brightness (gamma correction) and probably much more I can not think of right now... But back to your question the ...


11

The TI-99/4a has a CALL CHAR command to redefine one ASCII character at a time. The first argument is the ASCII code and the second is the 8x8 map expressed as a series of hex digits. (This is how I learned hexadecimal back in elementary school. Good times!)


11

You probably should cut down the resolution to 512x512. I actually worked with a graphics processing system (Earthviews by DBA Systems with the added AIMS (Advanced Image Management System) software). It was designed in the late 1970s, which is just before the time frame you mention. It had two monitors. One was the primary, a serial terminal used for ...


11

Older monitors had analog timing and, with one notable exception, were designed so that the signals presented on their inputs at any moment would fully describe the color to be displayed at that moment. The only monitors that used any sort of time multiplexing on their inputs were those that used the same analog composite color encoding methods used in ...


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