63

When colour television broadcasts began (1960s, in the UK; perhaps a little earlier in North America?) there weren't any local devices that customers might want to use. Broadcast TV was the only source of images that any home user could imagine. Adding extra circuitry to handle separated R, G, B and sync inputs (with appropriate protections against overload ...


36

Where did the 80x25 text terminal size come from? Quick answer: It's one Punch Card Per Line Resulting in 24/25 lines (cards) per screen when using a 4:3 tube and a reasonable font as dictated by proportions fostered since Roman times. Detailed Answer: Prior to the 1981 release of the IBM PC, the VT05 (72x20 1971), VT52 (80x12 1974), and VT100 (80x25 ...


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 ...


27

If you don't know, then the answer is "no". It certainly is possible to get a color CRT tube and matching electronics and fit them into a cleared out case. However, if you have to ask people on the internet, then I'm pretty sure that the responsible answer to give you is: Keep your hands off. CRT tubes are high voltage electronics. They are evacuated, i.e. ...


24

The EHT (extra-high-tension) circuits used to drive colour CRT displays run at 25kV (kilo-volts), and the capacitors contain enough stored charge to kill you stone dead if you touch the wrong thing, and the stored charge does not disappear as soon as you switch the device off. I would take it to a repair shop if I were you. The technicians will have the ...


23

It's a little cheaper to build all-in-one units because you only need one cabinet and one power supply, and you need fewer cables and connectors and supporting electronics. And back then, people didn't often have monitors that they could reuse on new computers, just televisions which often had only RF inputs and couldn't produce a sharp image for text. So ...


21

A lot of early PCs and terminals were designed to use either TVs or monitors that were built around CRTs that were built to the same specifications as TVs. While (traditional standard definition) TVs don't have a well defined upper limit of horizontal resolution, in practice few of them were capable of handling a signal which varied faster than about 13 or ...


21

Are they called "monochrome" monitors, or something else? Yes. Monochrome covers all that paint in Amber, Green, Blue or white on black. What I want is one of those with glowing green letters made of thin lines on a solid black screen. That sounds more as if you're looking for a vector display. Something incompatible with most old hardware and ...


21

Early colour TVs predated VCRs and home computers by many years. Even if it did not cost much, adding an RGB input would still be a cost for something that no one would use. However, it would have been more complex and expensive than you might expect today.


20

Many TV designs up into the 1970s were so called live chassis designs, which used one leg of the mains input as a reference ground. This saved materials and weight - given some early color TVs used 200+ watts at 100% duty cycle, you would have needed a rather bulky and heavy transformer, given that PSMPS technology was not really mature for consumer devices ...


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

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 setting allows for quite a bit more screen real estate on the Workbench screen, and is quite useful for productivity apps. For games, software control of overscan ...


18

The 1701 and 1702 are virtually identical. They have the same specs, tube, inputs, casing, and manufacturer. The only real difference is the 1701 is older (1982 to early '83, 1702 is late '83) and the fact that the 1701 shipped with a 5-pin composite video cable instead of an 8-pin luma-chroma cable in the box (both monitors support both inputs). A full ...


18

Horizontal deflection circuit is intended to make linearly increasing current in the deflection coil. At the end of ray scanning from left to right, the deflection coil should be re-magnetized in a short time by applying higher reverse voltage to it. Typical schematics for the circuit looks like this: http://repairfaq.cis.upenn.edu/sam/deflfaq.htm#dsbdc . ...


18

It’s a regular 80s-era TV set, specifically a Ferguson MC01 (from a 1986 Argos catalogue, see this article): the buttons are volume, brightness, contrast, colour, and channel selection buttons. This particular model was designed to be computer-friendly, with RGB support and automatic switching. Ferguson also produced an add-on for 48K ZX Spectrum computers, ...


18

My Amstrad CTM644 CRT 'monitor', makes a high pitched whine [...] My research indicates that this is just the scanning frequency of the tube, The ~15 kHz line frequency is the most likely source. More exactly, it's the retrace, as that's not only one of the most powerful moves the ray does - which equates to higher currents used to initiate it - but it's ...


17

A "monochrome" screen refers to any display which only displays one colour, based on the type of phosphor used. The type you are after is more specifically called a "green screen" monitor. Unfortunately an internet search for this term is going to produce a lot of stuff about movie green-screens - perhaps searching for "green screen ...


15

The 80 columns comes via IBM terminals such as the 3270, which themselves got it from IBM punched cards. There was no particular reason to pick 80 over some other width for punched cards except that it is a nice round number and reflects the engineering limits of the day. The 25 rows is due to the power-of-two nature of RAM chips. These were extremely ...


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.


15

What was the phosphor resolution? The usual specification quoted for CRT resolution is the 'dot pitch', or distance between groups of RGB phosphor dots. Here are some examples of IBM monitors produced from 1987 to 1993 (taken from here):- Model Year Standard size viewable pixels dot pitch (mm) notes 8513 1987 VGA 12" 10.4" 640x480 ...


15

Basically it's the 15625 Hz sawtooth-like signal that drives the horizontal deflection coil, that is heard because the generated magnetic field moves the coil. It's a problem with all TV CRT, on some is barely audible, in other is more noticeable because the coil is more able to move. You could also hear a 50/60 Hz lower tone sometimes caused by the ...


14

A form of this was used extensively for avionics displays. Known as the penetron (stop giggling), the CRT used a single gun and dual phosphor coatings (red and green). Each frame was drawn in two passes. In the first, low intensity scan the inner phosphor layer would be stimulated (generating, say, red light); a second scan at high beam intensity would ...


14

In the early 80s, cost of RAM for the framebuffer was the dominant factor, closely followed by RAM bandwidth. The difference in resolution between NTSC and PAL systems is minimal in comparison to these factors (note that despite the different number of lines per field and different field rate, each technology used a very similar line rate of ~64us per line, ...


14

This might just be stating the obvious, but Type 30 manual linked in the question describes the device as a random-position point-plotting cathode ray tube. Nowhere does the manual suggest it's a vector graphics display. It then further describes how the computer supplies the X,Y coordinates of a single point to be plotted. There is no facility to plot a ...


13

Based on a quick perusal of the November 1982 edition of Acorn User — a user base reliably rich enough at least to consider a monitor — options then included (size unstated where the advert omits it, but I think that implies 14"): colour BMC 1401: £240, £258.75 colour Microvitec 1431: £269, £270, £284 colour MC 370M: £289 unspecified brand colour: £325, £...


13

After pressing "AP2+CБP" key combination computer switches to extended memory mode, in which screen is reduced to 1/4 of original size giving about 12Kb memory of screen RAM to user (extending user RAM from 16K to 28K).


13

Yes, of course. Just keep in mind, it's not only the tube to be replaced, but the electronics as well. Essentially only keeping the shell. The 9 inch tube is of standard size, so finding one with the same mountings should be possible. Colour tubes do (usually) need more depth, which shoulf still be possible as the IIc monitor housing is rather long. That ...


12

I don’t think they ever recommended a monitor. As far as I can remember, Atari communications showed Atari computers on their own, or connected to TVs; see for example this 1200XL advert, and Atari UK’s magazine, Atari I/O (issues 2, 3, 4, and 5). At least in Europe, 8-bit Ataris produced nice video on most TVs (I didn’t grow up with NTSC so I don’t know how ...


12

Non-CRT monochrome screens used various colours related to the underlying technology: monochrome plasma screens were reddish-orange; see for example the PLATO terminals or the Toshiba 4400SX; early LCD screens were bluish, some more than others; I particularly remember early Toshiba laptops being notably blue (see this photo of a T1000), and many “graphical”...


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 ...


Only top voted, non community-wiki answers of a minimum length are eligible