List of Home Computers By Video Hardware - Explanation of The Terms Used in The Tables

Explanation of The Terms Used in The Tables

  • System Name, the name of the system, or if there are many similar versions, the name of the most well known variant, see Notes.
  • Year the year that the first version of this system came on the market.
  • Chip name the name of the chip that was used as the basis for the video logic.
  • Video RAM the maximum amount of RAM used for the video display, depending on the resolution used the system may use less.
  • Text mode(s) The numbers of characters per line and lines of text the system supported. Sometimes more than one mode was possible
  • Font extras describes extra graphical possibilities a video system had because of optional features of their character sets, there are currently three categories:
  • LC Some systems could only display upper case characters in text mode because of their limited character set, If a system was able to also support lower case letters in a text mode, (in any highres mode it is of course always possible), then there is LC (for Lower Case) in this column.
  • BG Some systems used a matrix of blocky pixels instead of a letter in their font sets (or used dedicated hardware to emulate them, like the TRS-80 did), to support some sort of all points addressable (APA) mode. Its hard to call this a "high resolution" mode, because the resolution could be as low as 80x48 pixels, but in any case you could draw pictures with them. In case of systems that used such a system as its "APA" mode there is BG (for Block Graphics) in this column.
  • SG Some other systems used semi graphical characters like box-drawing characters dots and card symbols, and "graphical building block" geometric shapes such as triangles to give the system the appearance it could do high resolution graphics while in reality it could not, Systems like that have SG (for semi graphical characters) in this column. Many systems like the PET had a few of such characters dedicated to block graphics for an APA mode as well, often only for 2x2 matrix characters. Sometimes the system filled (or could fill) a reprogrammable section of the font set which such characters, these systems mainly fall under the "soft font" heading. Note that the BG and SG entries are only used when the system relied on them, had them predefined in its default character set, or, (what often happened on early systems) had them printed on the keyboard keys for direct entry in combination with some kind of "graphic shift" key.
  • Soft Font when the system had a programmable font RAM instead of a static "font ROM", or when the video system did not have a hardware text mode, but painted text in the highres screen using software, the video display wasn't dependent on a permanent font set, in this case we are talking about a system with a "soft" font.
  • text colors The number of colors the characters could have. If more than one text mode is supported the text colors column also lists the same numbers in the same order.
  • Graphics modes The number of horizontal and Vertical pixels the system could display in a High resolution mode, where several high resolution modes exist each one is listed separately.
  • Graphics colors The number of colors each pixel could have in High resolution mode, If more than one high resolution mode is supported the graphics color mode also lists the numbers in the same order.
  • Color resolution in "high resolution mode" it was often the case that a certain pixel could not be given an arbitrary color, often certain clusters of pixels, (quite often 8x8 pixels large) shared the same "color attribute", so as to spare video memory, as a 8-bit computer only had a 64 KB address space, and the CPU often had limited capabilities to manipulate video memory, therefore it was often necessary to keep the video RAM size as small as possible, so a minimum of the address space of the micro was used, and also the video content could be changed relatively rapidly.
  • Palette Support If the system could translate a "logical color" into a (larger number) or true colors using a palette mechanism then this column lists the number of logical colors the palette could accept, and the number of colors it could translate to.
  • HW accel short for Hardware acceleration can take several forms, the most obvious form is "bit blitting", that is the moving of groups of pixels from one place in video memory to another without the CPU doing any of the moving, another often used technique is hardware scrolling which in fact emulates moving the whole screen in the video ram, a third form of hardware acceleration is the use of sprites implemented in hardware. Some systems also supported drawing lines (and sometimes rectangles) using special line drawing hardware. The entry in the column reveals which methods the hardware supported with a two letters for each method.
  • BL for blitter
  • SC for hardware scrolling support
  • SP for hardware sprite support
  • DR for hardware supported line drawing
  • Sprite details covers three facets of the sprite support hardware the system used. Each number in the table cell is preceded by two letters.
  • S# for the first facet, is the total number of hardware sprites the system could support, in hardware (not counting re-use of the same hardware). if the system doesn't support hardware sprites at all the table cell only contains "-" . If S# is 1 then the single sprite is most often used to support a mouse cursor.
  • SS for the second facet, is the size of the sprite in screen pixels'. A sprite could be displayed by the hardware, as a matrix of horizontal by vertical pixels. If more than one sprite size mode is available each one is listed.
  • SC for the third facet, is the number of Sprite colors, it gives the number of colors that a sprite could have. It is about the total number of colors that could be used to define the sprite (transparent NOT included), so if a sprite could only be displayed as a figure in a single color the number is 1. If more than one sprite size mode is available each one is listed.
  • SP for the forth facet, is the number of Sprites per scanline. Hardware spites use a kind of Z-buffer to determine which sprite is "on top". Availability of hardware to do this limits the number of sprites that can be displayed on each scanline. This number tells how many sprites could be displayed on a scanline before one of them became invisible because of hardware limitations.
  • Unique features If the video display has unique features (or limitations) they will be listed here, if space is a limitation the remaining special features are expressed as notes.

a "-" in a table cell means that the answer is irrelevant, unknown or in another way has no meaning, for example the sprite size of a system that does not support hardware sprites.

a "?" in a table cell means that the entry has not yet been determined. if a ? follows an entry it means that other options than the listed ones may also exist

"Mono" in a table cell means monochrome that is for example black on white, or black on green.

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