List of home computers by video hardware

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This is a list of home computers, sorted alphanumerically, which lists all relevant details of their Video Hardware.

Note: in cases of manufacturers who have made both home and personal computers, only machines fitting into the home computer category are listed.

For a simple list of home computers see List of home computers. For a list categorized by wordlength and CPU, see the list of home computers by category. For a list of microcomputers of the pre-home computer era, see the list of early microcomputers.

Contents 1 the importance of having capable video hardware 2 The main classes of video hardware 3 Explanation of the terms used in the tables 4 The list of homecomputers, and their video capabilities 5 Systems still unassigned to a category. (work to be done) 6 Notes 7 See also 8 External links

[edit] the importance of having capable video hardware

Early home computers all had quite similar hardware, they used either the 6502 the Z80 or sometimes the 6809 microprocessor, they could have only as little as 16 KB of RAM or as much as 128K, and they could use a small 8K BASIC interpreter, or an extended 12K BASIC.

But if you wanted to run a nice Video Game, all these specifications did not matter so much. What mattered much more was what kind of picture could be put on the screen, and how easy or hard it was for a software programmer to get enough capabilities out of the video hardware to create the effects necessary for his game(for example animations).

Case in point is the Commodore 64. It used the, (arguably) weakest of the three above mentioned microprocessors, and its BASIC was abysmal (it was the BASIC that was developed for the Commodore PET, (a computer without any high resolution graphics capabilities at all) but all that did not matter because it had the VIC-II chip. And the graphic capabilities of this chip, with its ease of use, (for a machine language programmer) made it possible to develop games for it that surpassed everything that other systems of the time had. Of course, its comparatively large memory and the audio capabilities of the C64, (that were second to none) were also needed to create great games, but that is material for other lists.

[edit] The main classes of video hardware

There are two main categories of solutions for a home computer to generate a video signal.

• a custom design, either build from discrete logic chips, or with some form of programmable logic.
• a system using some form of Video Display Controller (VDC), a chip that contained most of the logic circuitry needed to generate the video signal.

Systems in the first category were the most flexible, and could offer a wide ranges of (sometimes unique) capabilities, but generally speaking the second category could offer a much more complex system for a comparable lower price.

Note that for completeness I have also added systems that did not really have "Video" hardware in the conventional sense, but used 7-segment displays as a visual output device.

The VDC based systems can be divided into four sub-categories.

• 1 Video shift register based solutions, have a simple "video shifter chip", and the main CPU doing most of the complex stuff.

Only one example of such a chip for a home computer exists, the RCA CDP1861 used in the COSMAC VIP. It could only create a very low resolution monochrome graphic screen. The chip in the Sinclair ZX-81 also is a video shifter, but is not a dedicated chip but a programmable chip, an ULA. The CDP1861 however was specially designed for this task only. Dedicated Video shifter chips did have some use in very early game systems, most notable in the Atari 2600.

• 2 CRTC (Cathode Ray Tube Controller) based solutions. A CRTC is a chip that generates most of the basic timing and control signals. It must be complemented with some "Video RAM" and some other logic for the "arbitration", so that the CPU and the CRTC chip can share access to this RAM. To complete the design, a CRTC chip also needs some other support logic. For example a ROM containing the bitmap font for text modes, and logic to convert the output from the system into a video signal.

• 3 Video interface controllers were a step up on the ladder, these were true VLSI chips that integrated all of the logic that was in a typical CRTC based system, plus a lot more, into a single chip. The VIC-II chip is probably the best known chip of this category.

• 4 Video co-processor chips are Video interface controllers that can manipulate, and/or interprete and display, the contents of their own dedicated Video RAM without intervention from the main CPU.

[edit] 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.
• 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
• 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.
• Lower case 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 a "Yes" in this column.
• 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 same numbers in the same order.
• 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.
• # Sprites The total number of hardware sprites the system could support, in hardware (not counting re-use of the same hardware sprite).
• Sprite sizes the size, in screen pixels, a Sprite could be displayed in by the hardware, as a matrix of horizontal by vertical pixels. If more than one mode could be selected they are all listed.
• Sprite colors The total number of colors that could be used to define the sprite (transparent NOT included). If more than one sprite size mode is available each one is listed in the same order.
• Sprites per scan-line Hardware spites use a kind of Z-buffer to determine which sprite is "on top". This limits the number of sprites that can be displayed on each scan-line. This number tells how many sprites could be displayed on a scan-line before one of them became invisible because of hardware limitations.
• Unique features If the video display has unique features (or limitations) that could not be expressed in the table they will be listed here, as notes.

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

[edit] The list of homecomputers, and their video capabilities

Systems using Discrete Logic

System name	Video RAM	Text mode(s)	lower case	text colors	graphics modes	graphics colors	palette support	unique features
Acorn system 1,2,3,4,5	-	9 x 1	-	-	-	-	-	7 segment display
Apple I	729 Bytes[1]	40x24	No[2]	Monochrome	None	-	-	Dumb terminal[3]
Apple II	18K[4]	40x24[5]	Yes[6]	Monochrome[7]	40x48,[8] 280x192[9]	16,[10] 6[11][12]	None	4 line "caption"[13]
Comx-35	1472 Bytes	40x24	No[14]	8	40x96 240x192[15]	8 (4 colors per 6x4 pixels)	none	[16]
Datapoint 2200[17]	840 Bytes[18]	80x12	Yes	Monochrome	None	-	-	Shift registers for RAM[19]
TRS-80 Model 1	1K[20]	32x16 64x16	No	Monochrome	64x16 128x48	Monochrome	No	[21]

Systems using Programmable Logic

System name	Chip name	Video RAM	Text mode(s)	lower case	text colors	graphics modes	graphics colors	color resolution	palette support	# of sprites	Sprite sizes	sprites per scanline	unique features
Acorn Electron	ULA	20K (max)[22]	20×32 40×25 40×32 80×25 80×32[23]	Yes	4_or_16, 2_or_4, 2_or_4, 2, 2	160×256, 320x256, 640x256, 320x200, 640x200	4_or_16, 2_or_4, 2, 2, 2	160×256, 320x256, 640x256, 320x200,[24] 640x200	No	0	-	-	None
Amstrad PCW	ASIC[25]	23K	90x32[26][23]	Yes	Monochrome[27]	720x256	Monochrome[27]	-	-	0	-	-	Scroll RAM[28]
Sinclair Spectrum	ULA	6912 Bytes	32x24[23]	yes	8 (16)[29]	256x192	8 (16)	32 x 24	none	none	-	-	color limitations[30]
Timex/Sinclair TS2068	ULA	12288 Bytes (max)	32x24	yes	8	256x192, 256x192, 512x192	8,8,2	32x24, 32x192, monochrome	none	none	-	-	swapping between two 256x192 screens

Systems using a CRTC

System name	Chip name	Video RAM	Text mode(s)	lower case	text colors	graphics modes	graphics colors	palette support	# of sprites	Sprite sizes	sprites per scanline	unique features
ABC 800C	MC6845	16K	40x24	Yes	8	240x240	2	2 of 8	0	-	-	None
ABC 800M	MC6845	16K	80x24	Yes	2	240x240	2	2 of 8	0	-	-	None
Amstrad CPC[31]	MC6845	16K	20x25, 40x25, 80x25[23]	Yes	16, 4, 2	160x200, 320x200, 640x200	16, 4, 2	17 of 27	0	-	-	None
Amstrad CPC+	MC6845 + ASIC	16K	20x25, 40x25, 80x25[23]	Yes	16, 4, 2	160x200, 320x200, 640x200	16, 4, 2	32 of 4096	16[32]	16x16[33]	16	screen control[34]
Aster CT-80	MC6845	1K or 2K[35]	64x16, 32x16, 80x25, 40x25[36]	yes[37]	Monochrome	128x48, 160x75[38]	3 grayscales[39]	none	none	-	-	Dual memory map support[40]
Camputers Lynx	MC6845	32K[41]	40x24[23][42]	Yes	8[43]	256x248	8	none	0	-	-	fully pixel addressable in 8 colors

Systems using a Video Interface Controller (VIC)

System name	Chip name	Video RAM	Text mode(s)	lower case	soft fonts	text colors	graphics modes	graphics colors	palette support	# of sprites	Sprite sizes	sprites per scanline	unique features
Acorn Archimedes[44]	VIDC1	468KB	software	-	-	256	800x600	256	256 of 4096	None	-	-	Risc OS system
Acorn Atom	MC6847	6K	32x16	No	No	9	64x32[45] 68x48[46]64x64 128x64 128x64 128x96 128x96 128x192 128x192 256x192	9, 4, 4, 2, 4, 4, 2, 2, 4, 2	None	0	-	-	None
APF-1	MC6847	6K	32x16	No	No	9	64x32[45] 68x48[46] 64x64 128x64 128x64 128x96 128x96 128x192 128x192 256x192	9, 4, 4, 2, 4, 4, 2, 2, 4, 2	None	0	-	-	None
Apple IIe[47]	unknown[48]	19K[49]	40x24, 80x24	Yes	No[50]	Mono chrome	40x48, 80x48,[51] 280x192, 560×192[52]	16, 16, 6, 16[53]	none	none	-	-	[13]
Apple IIc[54][55]	unknown[56]	19K	40x24, 80x24	Yes[57]	No	Mono chrome	40x48, 80x48, 280x192, 560×192	16, 16, 6, 16	none	none	-	-	[13]
Laser 200[58]	MC6847	2K	32x16	No	No	9	64x32[45] 64x64 128x64	9, 4, 4[59]	None	0	-	-	None

Systems using a Video Co-Processor

System name	Chip name	Video RAM	Text mode(s)	lower case	soft fonts	text colors	graphics modes	graphics colors	palette support	# of sprites	Sprite sizes	sprites per scanline	unique features
Coleco Adam	TMS9918A[60]	16K	32x24[61]	Yes	Yes	2,16	64x48, 256x192, 256x160[62]	16,16,16	none	32	8x8, 16x16	4	[63] color limitations
Commodore VIC-20	VIC[64]	1.5K[65]	22x23[66]	Yes[67]	Yes	2[68]	176x184[69]	4[70]	No[71]	0	-	-	Some[72]
Commodore Amiga (first generation)[73]	AGNES[74] and DENISE[75]	1Mb "chipram"[76]	Any textsize up to 80x32[23]	Yes	Yes	2 to 32, 64[77]	320x200, 640x200 (and 320x400, 640x400 interlaced)[78]	2 to 32, 64[77] and 4096[79]	2 to 32 colors out of 4096 colors	8[80]	16 wide, arbitrary height[81]	8	Many unique features[82]
Commodore Amiga (second generation)[83]	Super-AGNES[84] and Super-DENISE[85]	2Mb "chipram"	Any textsize up to 160x32	Yes	Yes	2 to 32, 64, (4 in superhighres)[86]	320x200, 640x200, 320x400, 640x400,[87] 1280x200, 1280x256	2 to 32, 64 and 4096	2 to 32 colors out of 4096 colors	8	16 wide, arbitrary height	8	even more unique features[88]
Commodore Amiga (Third generation)[89]	Advanced Graphics Architecture (AGA)[90]	2Mb "chipram"	Any textsize up to 160x32	Yes	Yes	2 to 32, 64 (4 in superhighres).	320x200, 640x200, 320x400, 640x400, 1280x200, 1280x256	2 to 32, 64 and 4096 and 262144[91]	2 to 32 colors out of 4096 colors, 256 colors out of 16777216 colors	8	16 wide, arbitrary height	8	still more unique features[92]
Memotech MTX500[93]	TMS9918A[60]	16K	32x24 40x24	Yes	Yes	2,16	64x48, 256x192	16,16	none	32	8x8, 16x16	4	[63] color limitations
MSX-1	TMS9918A[60]	16K	32x24 40x24	Yes	Yes	2,16	64x48, 256x192	16,16	none	32	8x8, 16x16	4	[63] color limitations
TI-99/4	TMS9918[94]	16K	32x24[95]	No	Yes	2,16	64x48[96]	16,16[97]	none	32	8x8, 16x16	4	[63] color limitations
TI-99/4A	TMS9918A[60]	16K	32x24[95]	No[98]	Yes	2,16	64x48, 256x192	16,16[97]	none	32	8x8, 16x16	4	[63] color limitations

Systems that could not be classified, but about which some information is known

System name	Chip name	Video RAM	Text mode(s)	lower case	text colors	graphics modes	graphics colors	palette support	# of sprites	Sprite sizes	sprites per scanline	unique features
A7000+	unknown	1875KB, 768KB	software	-	32768, 256	800x600, 1024x768	32768, 256	unknown	None	-	-	Risc OS system
Panasonic JR-200	unknown	unknown[99]	32x24	Yes	8	192x256[100] 64x48	8	unknown	None	-	-	Serial attributes[101]

[edit] Systems still unassigned to a category. (work to be done)

Apple IIGS

Apple III

Atari 400

Atari 800

Atari XL

Atari XE

Atari ST

BBC Micro

Commodore PET

Commodore Max

Commodore 64

Commodore 16 and 116

Commodore Plus/4

Commodore 128

Compucolor 1

Compucolor 2

Compute-A-Color (By Victor-Lambada)

Cromemco Z-1

Cromemco Z-2

Cromemco C10

Cromemco Maximizer

Cromemco SCC

Cromemco System Zero

Cromemco System One

Cromemco System Two

Cromemco System Three

DAI Personal Computer

Dragon 32

Dragon 64

Colour Genie

BK-0010

Enterprise 64

Enterprise 128

Exidy Sorcerer

FM Towns

FX-9000P (by casio)

Grundy NewBrain

Galaksija

Heathkit H-8

PCjr

IBM PS/1

Iyonix

Interton VC 4000

Jupiter Ace

Laser 100

Laser 110

Laser 210

Laser 310

Link 480Z

Aquarius

Matra Alice

MSX-2

MSX-2+

Micro Bee

MOS KIM-1

Nascom 1

Nascom 2

Newbear 77/68

NEC PC-8801

NorthStar Horizon

NorthStar Advantage

NorthStar Dimension

Nimbus PC-186

Oric 1

Oric Atmos

Oric Telestrat

P2000

RiscPC

Pravetz

Pravetz series 8

RM 380Z

Rockwell AIM-65

SAM Coupé

Salora

Sharp MZ-40K

Sharp MZ-80K

Sharp MZ-80C

Sharp MZ-80B

Sharp MZ-80A

Sharp MZ-1200

Sharp MZ-2000

Sharp MZ-700

Sharp MZ-3500

Sharp MZ-2200

Sharp MZ-5500

Sharp MZ-800

Sharp MZ-1500

Sharp MZ-5600

Sharp MZ-6500

Sharp MZ-2500

Sharp MZ-8000

Sharp MZ-2800

Sharp X1

Sharp X68000

ZX80

ZX81

Sinclair QL

Sony SMC-70

Sony SMC-70G

Sony SMC-777

Sord IS-11

Sord M5

Sord M23

Sord M68

SVI-318

SVI-328

Tandy 1000

Tatung Einstein

Texet TX8000

Thomson MO5

Thomson MO6

Thomson TO7

Thomson TO7-70

Thomson TO9

Thomson TO8

Thomson TO9

Thomson TO8D

Tiki 100

TRS-80 Model 2

TRS-80 Model 3

TRS-80 Model 4

TRS-80 Color Computer 1

TRS-80 Color Computer 2

TRS-80 Color Computer 3

TRS-80 MC-10

UK101

Video Genie

Zenith Minisport

Zenith Z89

Zenith Z90

Zenith Z-100

[edit] Notes

1. ^ actually the real figure is more complex, its 6144 bits of which 5760 bits were actually used. This is so because the video data was stored, not in RAM, but in six Signetics 2504 "Dynamic shift registers" which each held 1024 bits. But only 40x24=960 locations in the shift register were actually used.
2. ^ the six bits per character location were only enough to address 64 characters, A Signetics 2513 character generator ROM held only uppercase characters and some other alphanumerical characters in a 5 x 7 matrix.
3. ^ The video display generator of the Apple 1 was NOT memory mapped but acted as a (very) Dumb terminal. Data was sent to the terminal through an 7 bit parallel port, and a strobe. Six bits were used to choose which character was displayed next, after the last one on the screen at the "cursor position". The six bits corresponded directly with the character selection bits of the Signetics 2513 character generator ROM. When the seventh (most significant) bit was high, it meant the six least significant bit's had to be interpreted as a "command", but only two commands existed. The "carriage return" command made it so that the next character would appear at the start of the next line, and the "clear screen" command which would fill all the video memory with spaces, and resetted the cursor position to the top left corner. A "busy" bit could be read from the terminal to determine it was ready to accept a new character. Interestingly the counters that were used to create the video timing were also used to create the RAM refresh signal for the 4K main memory. In many ways, the APPLE I's VDU resembles the one of the Datapoint 2200.
4. ^ The Apple 2 has a 1K text buffer for the 40x24 text mode or the 40x48 low resolution graphics mode, and a 8K frame buffer for the 280x192 High resolution graphics mode. But because the apple had two text and two graphics pages the total reserved memory for video is 18K. The first text/low-resolution page runs from 0400H to 07FFH, the second from 0800H to 0BFFH. The first high-resolution frame buffer runs from 2000H to 3FFFH and the second one from 4000H to 5FFFH.
5. ^ in a 5x7 dot matrix with one pixel on either side of characters and a one dot high space between each line.
6. ^ Characters could also be inverted or blinking, The arrangement was not completely ASCII compatible! Characters from 00H to 3FH were inverted, from 40H to 7FH were flashing, from 80H to 9FH uppercase characters only, from A0H to DF the normal complete set, and from E0H to FFH the lowercase characters only, so all 256 combinations were used
7. ^ The apple turns the colorburst circuitry during text modes off to give a clearer text
8. ^ using text mode, where instead of characters a stack of two pixels were displayed
9. ^ The apple only displayed 7 pixels of each byte of the frame buffer, the eight one was used to determine which color combinations the pixels of the other seven bits could have
10. ^ each byte of text mode ram was divided in two nibbles. The "lower" nibble determined the color of the top block, the upper nibble determined the color of the lower blok. The sixteen available colors were: black, magenta, dark blue, purple, dark green, grey 1, medium blue, light blue, brown, orange, grey 2, pink, light green, yellow, aquamarine, white
11. ^ There are six colors available in the High-Resolution Graphics mode: black, white, red, blue, green and violet. Each dot can be either black, white or a color, although not all colors are available for every dot. If a pixel would be 0 then the corresponding pixel would become black, if it was 1 It would become either white, or a color. Which color a pixel in a 7 pixel "line" of dots would become was determined both by the eight bit of the pixel data byte, but also by its bit location in the byte. If the bit was in the leftmost column on the screen, or in any even-numbered column, then it would appear violet. If the bit was in the rightmost pixel column, or any odd numbered column, it would become green, except when two even and odd pixels were on belongside each other, then both pixels would be white. All this is true for all seven pixels of a display byte where its eight bit would be 0 (off), if this bit was turned "on" (to 1), then the violet and green would be exchanged by blue and red.
12. ^ except in revision 0 board, which could only display 4 colors, black, white, green and violet, because the eight bit of the display byte had no effect
13. ^ ^{a b c} In high or low resolution graphics mode the apple could replace the bottom 32 display lines with a four line text "caption", so you could simultaneously display text and graphics.
14. ^ Except by reprogramming the characterset, But BASIC used uppercase only
15. ^ Using a programmable font (with 64 characters 6 pixels wide and 8 pixels high) that meant that not each pixel of the theoretical 240x192 could be individually addressed. In fact at most 64x6x8 = 3072 individual pixels could be addressed at any one time. One way to create a real highres mode was to program the characterset by diving the 6x8 pixels of the character into 2x4 zones (like the TRS-80 graphics mode which used 2x3 zones), in this way a 80x96 point addressable highres mode was feasible.
16. ^ The Comx-35 has a strange setup with minimal video ram, just 960 bytes character data and RAM for 64 programmable characters. No highres modes Each character was 6x8 pixels, leaving two pixels (bits) that were used to select one of four (foreground) colors per halve character
17. ^ The Datapoint 2200 is considered to be the first personal computer, and its CPU resembles Intel's first 8-bit processor, the 8008. This is the case because Intel copied the Datapoints CPU architecture! From the 8008 came the 8080, and from the 8080 and 8085 8-bit CPU, The 8086 was the 16-bit version, and from that the Pentium and all current CPU's used in PC's and Mac's. This not only makes the Datapoint the first PC, but also the granddaddy of all current PC's!
18. ^ Actually its 960 characters (12x80) of seven bit. There were 95 different characters in the 5x7 matrix character ROM, and the datapoint used 7-bits per character to address them
19. ^ The Datapoint used shift registers for its video RAM, and used the power line frequency timing (50 or 60 cycles per second) for a complete refresh cycle. When writing to the Display the CPU had to wait for the next "window", which came 50 (or 60) times a second. Then the CPU could write a single character, or (with special software) multiple characters, up to all 960.
20. ^ Actually its less than 1K, its 7168 bits, because there were only seven 1Kx1bit RAM's used to store the seven bits per character. That is also why lowercase could not easily be accomplished. Of the 128 possible characters 64 were used for the "pseudographics", and the remaining 64 came from a character generator PROM that only contained uppercase characters
21. ^ each character mapped to a matrix of 2x3 pixels to generate a semi-high resolution mode". No video ram arbitration logic meant that writing to the screen cause a lot of "snow".
22. ^ Depending on the screen mode used
23. ^ ^{a b c d e f g} All text output produced by software in Highres graphics modes
24. ^ spaced display with two blank horizontal lines following every 8 pixel lines
25. ^ It's unclear if the PCW's ASIC was a completely dedicated chip designed from scratch or a gate array
26. ^ because the margins were normally not used the actual line only had 80 characters
27. ^ ^{a b} Black and green
28. ^ with a resolution of 720 by 256. Even with one bit per pixel, the PCW's video buffer occupied 23 kB of RAM, making software scrolling far too slow for fluid text manipulation. In order to improve this, the PCW implemented roller RAM, with a 512-byte area of RAM used to hold the address of each line of display data, effectively allowing very rapid scrolling. The video system also fetched data in a special order designed so that plotting a character eight scan lines high would touch eight contiguous addresses. This meant that very fast Z80 copy instructions like LDIR could be used. Unfortunately, it meant that drawing lines and other shapes could be very complicated.
29. ^ Eight colors, but with two brightness levels, so actually with 16 color tints
30. ^ The Sinclair Spectrum high resolution screen has serious color limitations. Each 8x8 pixel block can have only one set of foreground and background colors. This is because of the separate 960 byte color table, (one byte for each 8x8 pixel block). In each of these bytes the lower three bits (0-2) are the background color, the next three higher bits (3-5) are the foreground color and the two remaining high order bits were used for a "bright" (6th) and a "blinking" (7th) bit, so you could say the sinclair had 16 colors, eight with low brightness, and eight with high brightness. Of course the color limitations of this design can cause some heavy attribute clashes, for which the Spectrum is indeed infamous. For more information see ZX Spectrum graphic modes.
31. ^ Pertaining to the Amstrad CPC 464, 472, 664 and 6128
32. ^ with an independent palette of 15 colours, but sprite pixels can also be transparent, and each logical color can be any of 4096 colours
33. ^ three levels of magnification, 1x, 2x and 4x. Independent for X and Y axis
34. ^ Additional screen controls have been added to allow split screen operation and facilitate smooth scrolling.
35. ^ Depending on the boot floppy used, the Aster reconfigured its internal memory map for use as a TRS-80 compatible machine or a fully CP/M compatible machine, including the location in the internal memory map of the video memory. In TRS-80 mode it used 1K (16 lines of 64 characters) and used all 8 -bits of the character to support a full set of 256 characters, and in CP/M compatible mode it used 2000 bytes (25 lines of 80 characters) with the same characterset
36. ^ in TRS-80 as well as in CP/M mode the Aster could switch to a display mode where it would only display the odd display memory bytes at double width. The 40x25 mode was initiated when the system was booted with a special Videotex terminal emulator program. In both modes a hardware "de-snowing" (Video memory arbitration system) system was employed that removed the bothersome "snow" that appeared on a TRS-80 screen whenever the system made a large amount of accesses to the video memory. The memory arbitration logic did not need software support, so it also worked with all existing software
37. ^ although the original TRS-80 model 1 did not support lowercase the Aster did. It also supported a second copy of the 2x3 semi graphics set that was dithered to emulate a "grey" version of the TRS-80 graphics pixels, and it supported a set of semi-graphics characters similar to the PETSCII set
38. ^ 160x75 only in the CP/M compatible mode
39. ^ Actually, the Aster could display the TRS-80 graphics in black (pixel off), white (pixel on) and one grayscale halfway in-between black and white, which was accomplished by dithering the pixels in the semi-graphics block with a checkerboard pattern
40. ^ The Aster system could switch "on the fly" between two completely different system architectures, and also switched its video logic and memory map accordingly, it also lowered the dot clock (crystal) in CP/M mode, so the 64X16 and 80x25 screens were equally wide
41. ^ Or less when one or more "display pages" were turned off. The lynk used a display page for each of the three primary colors. For example when the BASIC instruction TEXT was executed the lynx turned of the display panes for red and blue, so it could reclaim ⅔th of the memory for the display for bigger programs (with all planes on the Lynx had just 16K left for programs) and this also increased the speed of the system because the VDU did not prohibit the CPU access to the memory so often
42. ^ The lynx used a trick, the natural resolution of 256 pixels would have called for a display of only 32x24, but by only using 6 pixels wide characters the Lynx could fit in 40 per line, only a very large software overhead was needed, so the display was slow, so slow in fact that the software did not scroll a text screen but simply started on the top line again
43. ^ Black, blue, red, magenta. green, cyan, yellow and white
44. ^ There are many slightly different versions of this machine, with names such as "Acorn Risc PC", "BBC A300" and "Acorn A5000"
45. ^ ^{a b c} The characterset includes 8 (one set for each color) x16 characters with a 2x2 pixel matrix, with this a mixed text and semi graphics mode can be created that can display pixels in 8 colors against a black background, albeit with some color clash
46. ^ ^{a b} Another semigraphics mode, like the 32x64 mode, but exchanging a more limited number of color for a somewhat higher resolution
47. ^ The apple IIe used a dedicated chip to replace most of the discrete logic of the apple II, all comments for the apple II apply to the apple IIe, but the apple IIe has additional possibilities
48. ^ It is not known whether the special chip for the apple IIe had a name
49. ^ The Apple IIe had an extra 1K of video ram for the 80 columns text mode.
50. ^ The apple used a hardware character generator, But could not mix text and graphics except by displaying four lines of text beneath the graphics screen, also the text was strictly black and white, so often text on the screen was displayed using software so colored text could be displayed in different fonts
51. ^ double low resolution mode, using the extra 1K text mode
52. ^ using the "resolution doubler" originally developed for the double low resolution mode, uses the second bank of high resolution RAM.
53. ^ effectively the color resolution was only 140×192, due to pixel placement restriction
54. ^ And Apple IIc Plus, which has identical graphics capabilities
55. ^ has all the capabilities of the Apple IIe, and an improved character set
56. ^ It is not known whether the special chip for the apple IIc had a name
57. ^ The apple IIc now used a small part of the characterset to display special "mouse graphics" symbols, and the character ROM was doubled in size, so it was possible to switch to a characterset that could display extra local language characters and symbols such as accented letters such as "á", "é", "ç" etc.
58. ^ The VTech Laser 200 was also called the "Salora Fellow" (mainly in Scandinavia, particularly Finland), the "Texet TX8000" (in the United Kingdom) and the Dick Smith "VZ 200" (in Australia and New Zealand)
59. ^ On a 2x2 pixels basis, with two choices of background colors
60. ^ ^{a b c d} the "Texas Instruments TMS9918" is actually a familiy of devices. The TMS9918A outputs 60 Hz NTSC composite video and TMS9928 and TMS9929 output three separate signals (Y, R-Y and B-Y) with which either a 60Hz NTSC (TMS9928A) or a 50Hz PAL or SECAM (TMS9929A) video signal could be created
61. ^ A 40 x 24 text mode is theoretically possible but is not supported in Coleco BASIC
62. ^ Coleco Adam BASIC created a mode with a 256x160 pixel graphics "window" on top, and used the remaining 256x32 pixel window to create four lines of 32 characters of text
63. ^ ^{a b c d e} TMS9918/28 based systems: in 32x24 text mode the characterset is divided in 32 blocks of eight character. each block of eight characters can have a different foreground and background color. This can be used in games, because it is possible to generate a relatively fast high resolution mode by reprogramming the characters as 8x8 tiles and grouping them together in blocks of eight with the same colors. The tiles can then be manipulated quickly through the character pointer table. Sprites could be used too in this mode, and all 16 colors could be displayed at the same time. Another use is to have four identical character-sets with each 64 characters in them but with different colors. with this character set it is possible to create a 32x24 text mode that can display texts with four different foreground and background colors at the same time, on the same screen. In 256x192 graphics mode there is a 2-color limitation for each 8 pixel wide line inside a character, so this can cause some attribute clash although not as severe as on the ZX Spectrum.
64. ^ or 'Video interface controller', Pertaining to the MOS technology 6560 (NTSC version) and the 6561 (PAL version) chips. These chips did more than supporting the video display, they also provided the sound system, and had two A/D converters for it's paddle game control system
65. ^ The Vic could address 16 KB of address space for screen, character and color memory. But only 5 KB points to RAM on the VIC-20 without a hardware modification, and the VIC only had a grand total of 5K of which only 1.5K was reserved for the screen
66. ^ 8x8 characters, the VIC also supported 8x16 characters
67. ^ Like on the PET, 256 different characters could be displayed at a time, normally taken from one of the two character generators in ROM (one for upper-case letters and simple graphics, the other for mixed-case -- non-English characters were not provided)
68. ^ 2, because in the usual display mode, each character position could have its foreground colour chosen individually, and the background and screen border colours were set globally. A character could be made to appear in another mode where each pixel was chosen from 4 different colours: the character's foreground colour, the screen background, the screen border and an "auxiliary" colour; but this mode was rarely used since it made the already wide pixels pixels twice as wide as they normally were.
69. ^ 176 × 184 is the standard for the VIC-20 firmware, although at least 224 × 256 is possible on a PAL machine. The VIC chip did not provide for a direct full-screen, high-resolution graphics mode. It did, however, allow the pixel-by-pixel depictions of the on-screen characters to be redefined (by using a character generator in RAM), and it allowed for double-height characters (8 pixels wide, 16 pixels high). It was possible to get a fully-addressable screen, slightly smaller (160 by 160) than normal, by filling the screen with a sequence of 200 different double-height characters, then turning on the pixels selectively inside the RAM-based character definitions. (The 200-character limitation was so that enough bytes would be left over for the screen character grid itself to remain addressable by the VIC chip.) The Super Expander cartridge provided such a mode in BASIC, although it often had to move the BASIC program around in memory to do it. It was also possible to fill a larger area of the screen with addressable graphics using a more dynamic allocation scheme, if the contents were sparse or repetitive enough.
70. ^ For Highres graphics modes the double wide text mode was used, which proved for four different colors per pixel in each 8x16 character tile. For each tile the colors could be chosen out of a palette of 16 colors, but the upper 8 could only be used in the global background and auxiliary colors
71. ^ not really, but something similar could be done by manipulating the four colors out of sixteen possible color chosen for each tile, or the global background color
72. ^ The VIC-20 had hardware support for a Light pen, but it's most obvious feature was its text mode with very wide characters
73. ^ Pertaining to the Amiga 1000, Amiga 2000 and Amiga 500 machines
74. ^ For DMA memory access and Blitter functions, and a Copper (co-processor), a programmable finite state machine that executes a programmed instruction stream, synchronized with the video hardware
75. ^ the main video processor. Without using overscan, the display was 320 (lowres) or 640 (hires) pixels wide by 200 (NTSC) or 256 (PAL) tall. It also supported interlacing which doubled the vertical resolution. Anything between 2 and 32 unique colors (1 to 5 bitplanes) from a 12 bit (4096 color) palette, was supported. A 6th bitplane was available for either the Halfbrite mode that added a copy of the first 32 colors but with half the intensity or Hold And Modify mode which allowed access to all 4096 colors at once. Denise supported eight sprites, smooth scrolling, and "dual playfield". For more information see Original Amiga chipset.
76. ^ Older versions could only access 512KB chipram
77. ^ ^{a b} in "halfbright mode". Extra Half-Brite (EHB) mode uses 6 bitplanes (6 bits/pixel), where the first 5 bitplanes index a color from the color palette (consisting of 32 colors). If the bit on the 6th plane is set the color brightness is halved for each color component. This way 64 simultaneous colors are possible while only using 32 color palette registers.
78. ^ 320x256, 640x256, 320x512 and 640x512 in PAL mode
79. ^ Using "hold and modify" (HAM-6) mode, a mode specially designed for displaying photos, see Hold-and-Modify
80. ^ The Amiga's hardware engine supports only 8 sprites, but with copper support, can present the illusion of many more. Each sprite is drawn in a certain position, until the raster beam has passed it; the copper can then instantly change its location and appearance, moving it below the raster beam again
81. ^ 3 colours (plus a fourth transparent "colour"). Two sprites could be attached to make a single 15-color sprite.
82. ^ Too many to mention, see Original Amiga chipset
83. ^ Pertaining to the Amiga 3000 machines
84. ^ For DMA memory access and Blitter functions, and a Copper (co-processor), a programmable finite state machine that executes a programmed instruction stream, synchronized with the video hardware
85. ^ Could do all the things the original AGNES chip could and added support for Productivity (640×480 noninterlaced) and SuperHires (1280×200 or 1280×256) display modes, which were however limited to only 4 colors. Also the blitter could copy regions larger than 1024×1024 pixels in one operation. Sprites could be displayed in border regions (outside of any display window where bitplanes are shown).
86. ^ Four colors only in the new "super resolution" modes
87. ^ Now In non interlaced too
88. ^ Even more features than the original chipset, see Original Amiga chipset
89. ^ used in the CD32, Amiga 1200 and Amiga 4000.
90. ^ AGA is able to do 8-bit pixels, which gives 256 colors in normal display mode and 262144 colors in HAM-8 (Hold-And-Modify) mode (18-bit color, 6 bits per RGB channel). Palette for AGA chipset is 256 entries from 16777216 colors (24-bit). The original Amiga chipset (OCS) had 4096 colors (12-bit, 4 bits per RGB channel), of which 32 could be displayed unless in half-bright (which provided an additional 32 colors fixed at half the brightness of the first 32) or HAM mode.
91. ^ Using "hold and modify" (HAM-8) mode, a new super high color mode Hold-and-Modify
92. ^ Other features added to AGA over ECS were superhires smooth scrolling and 32-bit fast page memory fetches to supply the graphics data bandwidth for 8 bitplane graphics modes and wider sprites see Advanced Graphics Architecture
93. ^ The Memotech MTX512A and RS128 machines have the same video capabilities as the MTX500
94. ^ The TI99/4 was the only system to use the old TMS9918, instead of the TMS9918A. This VDP did not support mode II graphics
95. ^ ^{a b} A 40 x 24 mode was theoretically possible with assembler, but was not supported in TI-BASIC
96. ^ The TI-99/4 used a TMS9918 (not TMS9918A), and this older chip did not support 256x192 (mode II) Graphics
97. ^ ^{a b} Actually 15 colors, the 16th color was "transparent" and was designed to display a background video signal from a genlock
98. ^ No lower case support, but the TI-99/4A Did support "small characters" instead of lowercase
99. ^ The text buffer is 768 Bytes, but it is not known what the size of the color attribute ram is
100. ^ Not point addressable, but through a programmable character set
101. ^ It seems this system uses a serial attributes scheme, similar to the Oric Atmos but no details are known, perhaps it's just a feature of its BASIC.

[edit] See also

• List of home computers
• Video Display Controller

[edit] External links

• Obsolete technology website — Information about many old computers.
• old-computers.com — Web Site dedicated to old computers.