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104-631: The Tandy Color Computer line, nicknamed CoCo , started in 1980 with what is now called the Color Computer 1. It was followed by the Color Computer 2 in 1983, then the Color Computer 3 in 1986. All three models maintain a high level of software and hardware compatibility, with few programs written for an older model being unable to run on the newer ones. The Color Computer 3 was discontinued in 1991. All Color Computer models shipped with Color BASIC , an implementation of Microsoft BASIC, in ROM. Variants of

208-516: A 64K version of the CoCo 2 which also included an 'enhanced' full-travel, typewriter-style keyboard in the production run, replacing the previous "melted" keyboard. The final significant change in the life of the CoCo 2 (models 26-3134B, 26-3136B, and 26-3127B; 16K standard, 16K extended, and 64K extended respectively) was to use the enhanced VDG, the MC6847T1, allowing lowercase characters and changing

312-621: A PCB had holes drilled for each wire of each component. The component leads were then inserted through the holes and soldered to the copper PCB traces. This method of assembly is called through-hole construction . In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered . The patent they obtained in 1956

416-426: A PCB may have a coating that protects the copper from corrosion and reduces the chances of solder shorts between traces or undesired electrical contact with stray bare wires. For its function in helping to prevent solder shorts, the coating is called solder resist or solder mask . The pattern to be etched into each copper layer of a PCB is called the "artwork". The etching is usually done using photoresist which

520-461: A bitmap screen is 6144. The 256×192 two color graphics mode can display four colors due to a quirk in the NTSC television system. These are called composite artifact colors . In the first colorset, where green and black dots are available, alternating columns of green and black appear as a muddy green color. With the white and black colorset, the result is either orange or blue. Reversing the order of

624-506: A device. By default, device 0 (screen and keyboard) is assumed. In Color BASIC, device #-1 (cassette) and #-2 (printer) are available to the programmer. If you make a mistake typing in a line, you can either retype it from scratch (or DEL it).. or you can EDIT it. When in EDIT mode, you get a reprint of the line, and a second copy that you SPACEbar across chars. You cannot use arrow keys. backspace takes you left, but does not actually erase it in

728-522: A display device is to a TV. Early versions of the CoCo 1 have a black keyboard surround, the TRS-80 nameplate above the keyboard to the left side, and a RAM badge ("button") affixed on the top and right side of the case. Later versions removed the black keyboard surround and RAM button, and moved the TRS-80 nameplate to the mid-line of the case. The computer is based on a single printed-circuit board with all semiconductors manufactured by Motorola including

832-503: A few subroutines available for machine language programs in the Color BASIC ROM that are available for general purpose programming. Printed-circuit board A printed circuit board ( PCB ), also called printed wiring board ( PWB ), is a medium used to connect or "wire" components to one another in a circuit . It takes the form of a laminated sandwich structure of conductive and insulating layers: each of

936-460: A flat, narrow part of the copper foil that remains after etching. Its resistance , determined by its width, thickness, and length, must be sufficiently low for the current the conductor will carry. Power and ground traces may need to be wider than signal traces . In a multi-layer board one entire layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave circuits, transmission lines can be laid out in

1040-418: A general estimate of the board complexity. Using more layers allow for more routing options and better control of signal integrity, but are also time-consuming and costly to manufacture. Likewise, selection of the vias for the board also allow fine tuning of the board size, escaping of signals off complex ICs, routing, and long term reliability, but are tightly coupled with production complexity and cost. One of

1144-443: A general-purpose home computer. The internal modem was removed, and I/O ports for cassette storage, serial I/O , and joysticks were provided. An expansion connector was added to the right side of the case for future enhancements and ROM cartridges ("Program Paks"). A sticker indicating the amount of installed memory in the machine covers the hole where the modem's LED "DATA" indicator had been. On July 31, 1980, Tandy announced

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1248-786: A liquid ink that contains electronic functionalities. HDI (High Density Interconnect) technology allows for a denser design on the PCB and thus potentially smaller PCBs with more traces and components in a given area. As a result, the paths between components can be shorter. HDIs use blind/buried vias, or a combination that includes microvias. With multi-layer HDI PCBs the interconnection of several vias stacked on top of each other (stacked vías, instead of one deep buried via) can be made stronger, thus enhancing reliability in all conditions. The most common applications for HDI technology are computer and mobile phone components as well as medical equipment and military communication equipment. A 4-layer HDI microvia PCB

1352-475: A more extensive development environment that includes a copy of BASIC09 . C and Pascal compilers were available. Members of the CoCo OS-9 community enhanced OS-9 Level 2 for the CoCo 3 at Tandy's request, but Tandy stopped production of the CoCo 3 before the upgrade was officially released. Most of the improvements made it into NitrOS-9, a major rewrite of OS-9/6809 Level 2 for the CoCo 3 to take advantage of

1456-517: A pen and graphics tablet called the X-Pad, speech and sound generators, and joysticks. During the initial CoCo 1 production run, much of the discrete support circuitry had been re-engineered into a handful of custom integrated circuits , leaving much of the circuit board area of the CoCo 1 as empty space. To cut production costs, the case was shortened by about 25% and a new, smaller power supply and motherboard were designed. The "melted" keyboard from

1560-446: A planar form such as stripline or microstrip with carefully controlled dimensions to assure a consistent impedance . In radio-frequency and fast switching circuits the inductance and capacitance of the printed circuit board conductors become significant circuit elements, usually undesired; conversely, they can be used as a deliberate part of the circuit design, as in distributed-element filters , antennae , and fuses , obviating

1664-649: A print-and- etch method in the UK, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1925 patented a method of electroplating circuit patterns. Predating the printed circuit invention, and similar in spirit, was John Sargrove 's 1936–1947 Electronic Circuit Making Equipment (ECME) that sprayed metal onto a Bakelite plastic board. The ECME could produce three radio boards per minute. The Austrian engineer Paul Eisler invented

1768-600: A proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors , with ceramic disc capacitors and subminiature vacuum tubes soldered in place. The technique proved viable, and the resulting patent on the process, which was classified by the U.S. Army, was assigned to Globe Union. It was not until 1984 that the Institute of Electrical and Electronics Engineers (IEEE) awarded Harry W. Rubinstein its Cledo Brunetti Award for early key contributions to

1872-440: Is cotton paper impregnated with phenolic resin , often tan or brown. When a PCB has no components installed, it is less ambiguously called a printed wiring board ( PWB ) or etched wiring board . However, the term "printed wiring board" has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly ( PCA ), printed circuit board assembly or PCB assembly ( PCBA ). In informal usage,

1976-455: Is fire retardant , the dielectric constant (e r ), the loss tangent (tan δ), the tensile strength , the shear strength , the glass transition temperature (T g ), and the Z-axis expansion coefficient (how much the thickness changes with temperature). There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of

2080-428: Is a 5 dot wide by 7 dot high character in a box 8 dots wide and 12 lines high. This display mode occupies 512 bytes of memory from $ 400-$ 5FF and is a 32 character wide screen with 16 lines. The ROM character generator only holds 64 characters, so no lowercase characters are provided. "Lowercase" characters are rendered as uppercase with inverted color. On most CoCo generations it is green on very dark green. Semigraphics

2184-437: Is a common engineering error in high-frequency digital design; it increases the cost of the boards without a corresponding benefit. Signal degradation by loss tangent and dielectric constant can be easily assessed by an eye pattern . Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water also may be soaked by capillary forces through voids in

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2288-414: Is a mode where alphanumerics and low resolution graphics can be mixed together. The 8th bit of a character determines if it is alphanumeric or treated as a 2 × 2 pixel grid. When the 8th bit is set, the next three bits determine the color and last 4 bits specify which quadrants of the character box are either the selected color or black. This allows a 64 × 32 graphics mode with 9 colors, the only mode where it

2392-473: Is a multifunction device that performs the following functions: The SAM was designed to replace numerous small LS/ TTL chips into one integrated package. Its main purpose is to control the DRAM but, as outlined above, it integrates several other functions as well. It is connected to a crystal at 4 times the television colorburst frequency (14.31818 MHz for NTSC countries). This is divided by 4 internally and

2496-477: Is about 73, compared to about 4 for common circuit board materials. Absorbed moisture can also vaporize on heating, as during soldering , and cause cracking and delamination , the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required to dry them prior to soldering. Often encountered materials: Less-often encountered materials: Copper thickness of PCBs can be specified directly or as

2600-534: Is addressable as either on or off. There are two colorsets available: black dots on a green background with a green border, and white dots on a black background with a white border. In color modes, each pixel uses two bits to select one of four colors, with the overall colors determined by the colorset: Resolution graphics store 8 pixels per byte and are available in 128×64, 128×96, 128×192, and 256×192 modes. Color graphics have 4 pixels per byte and are available in 64×64, 128×64, 128×96, and 128×192. The maximum size of

2704-468: Is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability. FR-4 is by far the most common material used today. The board stock with unetched copper on it is called "copper-clad laminate". With decreasing size of board features and increasing frequencies, small nonhomogeneities like uneven distribution of fiberglass or other filler, thickness variations, and bubbles in

2808-655: Is available to do much of the work of layout. Mass-producing circuits with PCBs is cheaper and faster than with other wiring methods, as components are mounted and wired in one operation. Large numbers of PCBs can be fabricated at the same time, and the layout has to be done only once. PCBs can also be made manually in small quantities, with reduced benefits. PCBs can be single-sided (one copper layer), double-sided (two copper layers on both sides of one substrate layer), or multi-layer (outer and inner layers of copper, alternating with layers of substrate). Multi-layer PCBs allow for much higher component density, because circuit traces on

2912-451: Is coated onto the PCB, then exposed to light projected in the pattern of the artwork. The resist material protects the copper from dissolution into the etching solution. The etched board is then cleaned. A PCB design can be mass-reproduced in a way similar to the way photographs can be mass-duplicated from film negatives using a photographic printer . FR-4 glass epoxy is the most common insulating substrate. Another substrate material

3016-533: Is compatible with most older software and CoCo 2 peripherals. The 6809 in the CoCo 1 and 2 runs at 0.895 MHz. The CoCo 3 runs at that frequency by default, but is software controllable to run at twice that rate; OS-9 takes advantage of that capability. Taking the place of the graphics and memory hardware in the CoCo 1 and 2 is an application-specific integrated circuit called the GIME (Graphics Interrupt Memory Enhancement) chip. The GIME also provides: Omitted from

3120-418: Is equivalent in quality to an 8-layer through-hole PCB, so HDI technology can reduce costs. HDI PCBs are often made using build-up film such as ajinomoto build-up film, which is also used in the production of flip chip packages. Some PCBs have optical waveguides, similar to optical fibers built on the PCB. A basic PCB consists of a flat sheet of insulating material and a layer of copper foil , laminated to

3224-632: Is estimated to reach $ 79 billion by 2024. Before the development of printed circuit boards, electrical and electronic circuits were wired point-to-point on a chassis. Typically, the chassis was a sheet metal frame or pan, sometimes with a wooden bottom. Components were attached to the chassis, usually by insulators when the connecting point on the chassis was metal, and then their leads were connected directly or with jumper wires by soldering , or sometimes using crimp connectors, wire connector lugs on screw terminals, or other methods. Circuits were large, bulky, heavy, and relatively fragile (even discounting

TRS-80 Color Computer - Misplaced Pages Continue

3328-598: Is fed to the VDG for its own internal timing (3.579545 MHz for NTSC). The SAM also divides the master clock by 16 (or 8 in certain cases) for the two phase MPU clock ; in NTSC this is 0.89 MHz (or 1.8 MHz if divided by 8). Switching the SAM into 1.8 MHz operation gives the CPU the time ordinarily used by the VDG and refresh. As such, the display shows garbage; this mode was seldom used. However, an unusual mode available by

3432-406: Is possible to display all 9 colors simultaneously. There are two colorsets. The default has black characters on a green background. The alternate has black characters on an orange background. The colorset selection does not affect semigraphics characters. The border is always black. The 6847 is capable of a Semigraphics 6 display mode, where two bits select a color and 6 bits determine which 1/6 of

3536-466: Is possible to subdivide the character box into smaller pieces. This creates the "virtual" modes Semigraphics 8, 12, and 24. In these modes it was possible to mix bits and pieces of different text characters as well as Semigraphics 4 characters. These modes were an interesting curiosity but not widely used, as the Semigraphics 24-screen consumed 6144 bytes of memory. These modes were not implemented on

3640-607: Is required for the next level of BASIC, Extended Color BASIC ("ECB"). Extended BASIC is required for the floppy disk controller , which then gives you Disk Extended Color BASIC ("DECB"). Emulators of the Color Computers running this interpreter and the others are available for modern computers, some of which require a "snapshot" file of the physical machine. Color BASIC understands one type of numeric variable and string variables. Variable names in Color BASIC have

3744-621: Is the implementation of Microsoft BASIC that is included in the ROM of the Tandy/Radio Shack TRS-80 Color Computers manufactured between 1980 and 1991. BASIC (Beginner's All-purpose Symbolic Instruction Code) is a high level language with simple syntax that makes it easy to write simple programs. Color BASIC is interpreted , that is, decoded as it is run. The nucleus of Color BASIC was Microsoft BASIC-69 which Tandy licensed from Microsoft. Color BASIC 1.0

3848-471: Is the most common thickness; 2 oz (70 μm) and 0.5 oz (17.5 μm) thickness is often an option. Less common are 12 and 105 μm, 9 μm is sometimes available on some substrates. Flexible substrates typically have thinner metalization. Metal-core boards for high power devices commonly use thicker copper; 35 μm is usual but also 140 and 400 μm can be encountered. In the US, copper foil thickness

3952-409: Is written is ignored. Due to limitations in 40-pin packaging, the SAM contains a duplicate of the VDG's internal 12-bit address counter. Normally this counter's settings are set to duplicate the VDG's display mode. However, this is not required and results in the creation of some new display modes not possible when the VDG is used in a system alone. Instead of the VDG requesting data from RAM by itself,

4056-544: The Commodore 64 , and that Radio Shack was dedicated to the educational market while Commodore was not. By 1985, Color Computer users worried that the company would abandon their computer in favor of the Tandy 1000 . Tandy executive Ed Juge stated that year that "No home computer on the market today has the potential horsepower of the Color Computer ... we believe [it] also has a good future". On July 30, 1986, Tandy announced

4160-663: The OS-9 multitasking operating system were available from third parties. Tandy Corporation announced the TRS-80 Color Computer in July 1980 as a low-cost home computer. The Color Computer is a completely different design than the Zilog Z80 -based TRS-80 models. BYTE wrote, "The only similarity between [the two computers] is the name". The TRS-80 Color Computer derives from an "experimental videotext project by

4264-449: The glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding T g then exerts mechanical overload on the board components - e.g. the joints and the vias. Below T g the thermal expansion of the resin roughly matches copper and glass, above it gets significantly higher. As the reinforcement and copper confine the board along the plane, virtually all volume expansion projects to

TRS-80 Color Computer - Misplaced Pages Continue

4368-399: The signal propagation speed , frequency dependence introduces phase distortion in wideband applications; as flat a dielectric constant vs frequency characteristics as is achievable is important here. The impedance of transmission lines decreases with frequency, therefore faster edges of signals reflect more than slower ones. Dielectric breakdown voltage determines the maximum voltage gradient

4472-500: The "high speed POKE " was used by many CoCo BASIC programs even though it overclocked the hardware in the CoCo, which was only rated for 1 MHz operation. The SAM has no connection to the MPU data bus. As such, it is programmed in a curious manner; its 16-bit configuration register is spread across 32 memory addresses (FFC0-FFDF). Writing even bytes sets that register bit to 0, while writing odd bytes sets it to 1. The value (D7-D0) that

4576-490: The CoCo 3. A programmer's reference manual for the CoCo states that due to a fire at Tandy's research lab, the papers relating to the semigraphics modes were shuffled, and so some of the semigraphics modes were never documented. CoCo enthusiasts created experimental programs to try to reverse engineer the modes, and were able to reconstruct the missing documentation. Bitmap display modes are divided into two categories: resolution and color . In resolution modes, each pixel

4680-474: The CoCo and the TDP System 100 shipped with a white case with ventilation slots running the length of the case rather than only the sides. This ventilation scheme carried over to the CoCo 2. Some late versions of the CoCo have a modified keyboard, often referred to as the "melted" keyboard, with bigger keycaps . Peripherals included tape cassette storage, serial printers , a 5.25-inch floppy disk drive ,

4784-661: The Color Computer 3 at the Waldorf-Astoria Hotel in New York City. It came with 128 KB of RAM, which could be upgraded to 512 KB. The panel behind the keyboard and cartridge door plastic were changed from black to grey. The keyboard layout was revised, putting the arrow keys in a diamond configuration and adding CTRL , ALT , CLEAR , F1 and F2 keys. It sold in Radio Shack stores and Tandy Computer Centers for $ 219.95. The CoCo 3

4888-527: The GIME are the seldom-used SAM-created Semigraphics 8, 12, and 24 modes. A rumored 256-color mode (detailed in the original Tandy spec for the GIME) has never been found. Previous versions of the CoCo ROM were licensed from Microsoft, but Tandy could not convince them to provide further BASIC updates. Instead, Microware provided extensions to Extended Color BASIC to support the new display modes. To not violate

4992-560: The Kentucky Cooperative Extension Service and the University of Kentucky College of Agriculture " in 1977. Motorola Semiconductor of Austin, Texas , won the contract for the user terminals and Tandy's Computer Division joined later to manufacture the terminals. The initial goal of this project, called "Green Thumb", was to create a low cost videotex terminal for farmers, ranchers, and others in

5096-515: The MC6809E CPU, MC6847 VDG, MC6883 SAM, and RAM, which consists of 2104 (4Kx1) chips (4K models) or 4116 (16Kx1) chips (16K models). The early CoCos only have eight RAM sockets, so upgrading to 32K requires piggybacking two sets of 4116 chips and adding a few jumper wires. A later motherboard revision removed the 4K RAM option and were upgraded to 32K with "half-bad" 4164 DRAMs. These boards have jumpers marked HIGH/LOW to determine which half of

5200-558: The PCB surface, instead of wire leads to pass through holes. Components became much smaller and component placement on both sides of the board became more common than with through-hole mounting, allowing much smaller PCB assemblies with much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labor costs and greatly increasing production rates compared with through-hole circuit boards. Components can be supplied mounted on carrier tapes. Surface mount components can be about one-quarter to one-tenth of

5304-646: The SAM is called the Address Dependent mode, where ROM reads (since they do not use the DRAM) occur at 1.8 MHz but regular RAM access occurs at 0.89 MHz. In effect, since the BASIC interpreter runs from ROM, putting the machine in this mode would nearly double the performance of a BASIC program while maintaining video display and DRAM refresh. Of course, this would throw off the software timing loops and I/O operations would be affected. Despite this, however,

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5408-636: The TRS-80 Color Computer, which shares the same case, keyboard, and layout as the AgVision/VideoTex terminals. Tandy viewed businesses as its primary market for computers. Although the company's Ed Juge said in 1981 that the Color Computer was "our entry into the home-computer market", he described it as "for serious professionals", stating that a word processor and spreadsheet would soon be available. The initial model (catalog number 26-3001) shipped with 4 KB of dynamic random access memory (DRAM) and 8 KB Microsoft BASIC in ROM . Its price

5512-454: The VDG is "fed" data by the SAM's internal copy of the VDG address counter. This process is called "Interleaved Direct Memory Access" (IDMA) by Motorola and ensures that the processor and VDG always have full access to this shared memory resource with no wait states or contention. There are two versions of the SAM. The early one is labeled MC6883 and/or SN74LS783; the later version is labeled SN74LS785. There are some minor timing differences, but

5616-541: The agricultural industry. This terminal would connect to a phone line and an ordinary color television and allow the user access to near-real-time information useful to their day-to-day operations on the farm. Motorola's MC6847 Video Display Generator (VDG) chip was released about the time the joint venture started. The 1978 prototype "Green Thumb" terminal used the MC6847 and the Motorola 6809 microprocessor. However,

5720-418: The alternating dots gives the opposite color. In effect, this mode is 128×192 with four colors: black, orange, blue, and white. On PAL televisions, instead of solid orange and blue, artifacts appear as vertical stripes of green and peach with soft edges and a width of almost four pixels. On a CoCo 3 with an analog RGB monitor, the black and white dot patterns do not artifact. Color BASIC Color BASIC

5824-453: The back of the board in opposite directions to improve the part's mechanical strength), soldering the leads, and trimming off the ends. Leads may be soldered either manually or by a wave soldering machine. Surface-mount technology emerged in the 1960s, gained momentum in the early 1980s, and became widely used by the mid-1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be soldered directly onto

5928-437: The board and soldered onto copper traces on the other side. Boards may be single-sided, with an unplated component side, or more compact double-sided boards, with components soldered on both sides. Horizontal installation of through-hole parts with two axial leads (such as resistors, capacitors, and diodes) is done by bending the leads 90 degrees in the same direction, inserting the part in the board (often bending leads located on

6032-519: The breakable glass envelopes of the vacuum tubes that were often included in the circuits), and production was labor-intensive, so the products were expensive. Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented

6136-502: The buffer. 'i' puts you in insert mode. pressing return gets you out of it. 'c' changes one char, 'd' deletes one char. 'x' takes you to end of line, allowing you to e'x'tend it. 'l' redraws the line. 's' searches for the next instance of a character. For the 's', 'c' and 'd' commands you can also enter a number (#) before pressing any of them which will: 's' - search for the # instance of the character, 'c' - allow you to change # of characters, 'd' - delete # amount characters. There are

6240-524: The ceramic substrate. In 1948, the US released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. At around the same time in the UK work along similar lines was carried out by Geoffrey Dummer , then at the RRDE . Motorola was an early leader in bringing

6344-493: The character box is lit. Only 4 colors are possible, but the colorset bit of the VDG selects two groups of 4 colors. Only two colors are available in graphics blocks when using Semigraphics 6 on the CoCo. The default alphanumeric display for the CoCo is Semigraphics 4. By setting the SAM such that it believes it is displaying a full graphics mode, but leaving the VDG in Alphanumeric/Semigraphics 4 mode, it

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6448-539: The circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well known pre-preg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion

6552-488: The components to the board. Another manufacturing process adds vias , drilled holes that allow electrical interconnections between conductive layers. Printed circuit boards are used in nearly all electronic products. Alternatives to PCBs include wire wrap and point-to-point construction , both once popular but now rarely used. PCBs require additional design effort to lay out the circuit, but manufacturing and assembly can be automated. Electronic design automation software

6656-431: The components, test points , or identifying text. Originally, silkscreen printing was used for this purpose, but today other, finer quality printing methods are usually used. Normally the legend does not affect the function of a PCBA. A printed circuit board can have multiple layers of copper which almost always are arranged in pairs. The number of layers and the interconnection designed between them (vias, PTHs) provide

6760-412: The conductive layers is designed with a pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers, generally by means of soldering , which both electrically connects and mechanically fastens

6864-471: The desired final thickness and dielectric characteristics. Available standard laminate thickness are listed in ANSI/IPC-D-275. The cloth or fiber material used, resin material, and the cloth to resin ratio determine the laminate's type designation (FR-4, CEM -1, G-10 , etc.) and therefore the characteristics of the laminate produced. Important characteristics are the level to which the laminate

6968-440: The development of printed components and conductors on a common insulating substrate. Rubinstein was honored in 1984 by his alma mater, the University of Wisconsin-Madison , for his innovations in the technology of printed electronic circuits and the fabrication of capacitors. This invention also represents a step in the development of integrated circuit technology, as not only wiring but also passive components were fabricated on

7072-403: The dielectric constant). The reinforcement type defines two major classes of materials: woven and non-woven. Woven reinforcements are cheaper, but the high dielectric constant of glass may not be favorable for many higher-frequency applications. The spatially nonhomogeneous structure also introduces local variations in electrical parameters, due to different resin/glass ratio at different areas of

7176-558: The features and speed of the Hitachi 6309 (if available). A joystick adapter designed by Steve Bjork increases the resolution of the joystick/mouse interface by a factor of ten at the expense of CPU time . Internally the CoCo 1 and CoCo 2 models are functionally identical. The core of the system is virtually identical to the reference design included in the Motorola MC6883 data sheet and consists of five LSI chips: The SAM

7280-405: The finished multilayer board) are plated-through, before the layers are laminated together. Only the outer layers need be coated; the inner copper layers are protected by the adjacent substrate layers. "Through hole" components are mounted by their wire leads passing through the board and soldered to traces on the other side. "Surface mount" components are attached by their leads to copper traces on

7384-428: The first truly easy-to-use and inexpensive system that generates full-color graphics". Eventually the 32K memory option was dropped entirely and only 16K or 64K versions were offered. In late 1982, a version of the Color Computer with a white case, called the TDP System 100, was distributed by RCA and sold through non-Tandy stores. Except for the nameplate and case, it is identical to the Color Computer. Later, both

7488-470: The first two characters significant. The first character of the variable name must be a letter. The second can be either a letter or number. String variables are indicated by adding a dollar sign ($ ) after the variable name. Numeric variables have only one type, a binary floating point implementation. Each numeric variable uses 5 bytes of memory and can be in the range from -1E+38 up to 1E+37. Unlike most implementations of Microsoft BASIC, Color BASIC requires

7592-486: The following operators are used: Other symbols used in BASIC: num indicates a numeric expression is required. This can be a fixed number, a variable, or other operation or function that returns a numeric quantity. str indicates a string expression is required. This can be a static string value (in quotes), a string variable, or other function or expression that returns a string of characters. device number indicates

7696-447: The inner layers would otherwise take up surface space between components. The rise in popularity of multilayer PCBs with more than two, and especially with more than four, copper planes was concurrent with the adoption of surface mount technology . However, multilayer PCBs make repair, analysis, and field modification of circuits much more difficult and usually impractical. The world market for bare PCBs exceeded $ 60.2 billion in 2014 and

7800-427: The internal layers is used as ground plane or power plane, to achieve better signal integrity, higher signaling frequencies, lower EMI, and better power supply decoupling. In multi-layer boards, the layers of material are laminated together in an alternating sandwich: copper, substrate, copper, substrate, copper, etc.; each plane of copper is etched, and any internal vias (that will not extend to both outer surfaces of

7904-576: The major difference is the support of an 8-bit refresh counter in the 785 version. This allowed for use of inexpensive 16K by 4-bit and certain 64K by 1-bit DRAMs. Some third-party bank-switching memory upgrades that used 256K DRAMs needed this 8-bit refresh counter to work. The Motorola 6847 is display generator capable of displaying text and graphics contained within a roughly square display matrix 256 pixels wide by 192 lines high. It can display 9 colors: black, green, yellow, blue, red, white, cyan, magenta, and orange. In alphanumeric mode, each character

8008-498: The material can be subjected to before suffering a breakdown (conduction, or arcing, through the dielectric). Tracking resistance determines how the material resists high voltage electrical discharges creeping over the board surface. Loss tangent determines how much of the electromagnetic energy from the signals in the conductors is absorbed in the board material. This factor is important for high frequencies. Low-loss materials are more expensive. Choosing unnecessarily low-loss material

8112-495: The materials and along the reinforcement. Epoxies of the FR-4 materials are not too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water

8216-509: The memory chip was good. As memory production yields improved and costs went down, many (perhaps most) 32K CoCo 1s shipped with perfectly good 4164 memory chips. Utilities and programs began to take advantage of the hidden 32K. Users opening the case risked invalidating the warranty. Radio Shack could upgrade all versions that shipped with standard Color BASIC to Extended Color BASIC, developed by Microsoft , for $ 99. BYTE wrote in 1981 that through Extended Color BASIC, Radio Shack "has released

8320-498: The need for additional discrete components. High density interconnects (HDI) PCBs have tracks or vias with a width or diameter of under 152 micrometers. Laminates are manufactured by curing layers of cloth or paper with thermoset resin under pressure and heat to form an integral final piece of uniform thickness. They can be up to 4 by 8 feet (1.2 by 2.4 m) in width and length. Varying cloth weaves (threads per inch or cm), cloth thickness, and resin percentage are used to achieve

8424-471: The point-to-point chassis construction method remained in common use in industry (such as TV and hi-fi sets) into at least the late 1960s. Printed circuit boards were introduced to reduce the size, weight, and cost of parts of the circuitry. In 1960, a small consumer radio receiver might be built with all its circuitry on one circuit board, but a TV set would probably contain one or more circuit boards. Originally, every electronic component had wire leads , and

8528-646: The printed circuit as part of a radio set while working in the UK around 1936. In 1941 a multi-layer printed circuit was used in German magnetic influence naval mines . Around 1943 the United States began to use the technology on a large scale to make proximity fuzes for use in World War II. Such fuzes required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted

8632-478: The process into consumer electronics, announcing in August 1952 the adoption of "plated circuits" in home radios after six years of research and a $ 1M investment. Motorola soon began using its trademarked term for the process, PLAcir, in its consumer radio advertisements. Hallicrafters released its first "foto-etch" printed circuit product, a clock-radio, on November 1, 1952. Even as circuit boards became available,

8736-615: The prototype contained too many chips to be commercially viable. Motorola responded by integrating the functions of many smaller chips into one chip: the MC6883 Synchronous Address Multiplexer (SAM). The SAM, VDG, and 6809 were used as the core of the AgVision terminal. It was also sold through Radio Shack stores as the VideoTex terminal around 1980. The VideoTex terminal provided the foundation for

8840-403: The protruding wires are cut off and discarded. From the 1980s onward, small surface mount parts have been used increasingly instead of through-hole components; this has led to smaller boards for a given functionality and lower production costs, but with some additional difficulty in servicing faulty boards. In the 1990s the use of multilayer surface boards became more frequent. As a result, size

8944-441: The resin matrix, and the associated local variations in the dielectric constant, are gaining importance. The circuit-board substrates are usually dielectric composite materials. The composites contain a matrix (usually an epoxy resin ) and a reinforcement (usually a woven, sometimes nonwoven, glass fibers, sometimes even paper), and in some cases a filler is added to the resin (e.g. ceramics; titanate ceramics can be used to increase

9048-478: The same side of the board. A board may use both methods for mounting components. PCBs with only through-hole mounted components are now uncommon. Surface mounting is used for transistors , diodes , IC chips , resistors , and capacitors. Through-hole mounting may be used for some large components such as electrolytic capacitors and connectors. The first PCBs used through-hole technology , mounting electronic components by lead inserted through holes on one side of

9152-408: The simplest boards to produce is the two-layer board. It has copper on both sides that are referred to as external layers; multi layer boards sandwich additional internal layers of copper and insulation. After two-layer PCBs, the next step up is the four-layer. The four layer board adds significantly more routing options in the internal layers as compared to the two layer board, and often some portion of

9256-414: The size and weight of through-hole components, and passive components much cheaper. However, prices of semiconductor surface mount devices (SMDs) are determined more by the chip itself than the package, with little price advantage over larger packages, and some wire-ended components, such as 1N4148 small-signal switch diodes, are actually significantly cheaper than SMD equivalents. Each trace consists of

9360-558: The spirit of the licensing agreement between Microsoft and Tandy, Microsoft's unmodified BASIC is loaded in the CoCo 3's ROM. Upon startup, the ROM is copied to RAM and patched by Microware's code. The patched code has several bugs, and support for many of the new hardware features is incomplete. Microware also provided a version of the OS-9 Level 2 operating system shortly after launch. OS-9 uses memory-mapping (so each process has its own memory space up to 64K), windowed display, and

9464-422: The substrate. Chemical etching divides the copper into separate conducting lines called tracks or circuit traces , pads for connections, vias to pass connections between layers of copper, and features such as solid conductive areas for electromagnetic shielding or other purposes. The tracks function as wires fixed in place, and are insulated from each other by air and the board substrate material. The surface of

9568-402: The term "printed circuit board" most commonly means "printed circuit assembly" (with components). The IPC preferred term for an assembled board is circuit card assembly ( CCA ), and for an assembled backplane it is backplane assembly . "Card" is another widely used informal term for a "printed circuit assembly". For example, expansion card . A PCB may be printed with a legend identifying

9672-572: The text screen border color. These features were not enabled in BASIC. Midway during the production run of these models, the nameplate was changed from "Radio Shack TRS-80 Color Computer 2" to "Tandy Color Computer 2". The red, green, and blue shapes were replaced with red, green, and blue parallelograms . Creative Computing wrote in December 1984 that the Color Computer was the best educational computer under $ 1000. The magazine said that it had fewer but better-quality educational software titles than

9776-419: The thickness and stresses the plated-through holes. Repeated soldering or other exposition to higher temperatures can cause failure of the plating, especially with thicker boards; thick boards therefore require a matrix with a high T g . The materials used determine the substrate's dielectric constant . This constant is also dependent on frequency, usually decreasing with frequency. As this constant determines

9880-524: The user to reserve space for string variables via the CLEAR statement. Multidimensional arrays are also supported with both numeric and string variables. In the case of an array, the element address is enclosed with a parenthesis: Multiple dimensions are separated by commas Color BASIC provides several operators for both mathematic and, to a lesser extent, string operations. Parenthesis ( ) are used to override mathematical order of operation For testing,

9984-511: The weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications. The substrates are characterized by several key parameters, chiefly thermomechanical ( glass transition temperature , tensile strength , shear strength , thermal expansion ), electrical ( dielectric constant , loss tangent , dielectric breakdown voltage , leakage current , tracking resistance ...), and others (e.g. moisture absorption ). At

10088-440: The weight of copper per area (in ounce per square foot) which is easier to measure. One ounce per square foot is 1.344 mils or 34 micrometers thickness. Heavy copper is a layer exceeding three ounces of copper per ft , or approximately 0.0042 inches (4.2 mils, 105 μm) thick. Heavy copper layers are used for high current or to help dissipate heat. On the common FR-4 substrates, 1 oz copper per ft (35 μm)

10192-508: The white CoCo 1 and the TDP-100 style ventilation slots were carried over. Aside from the new look and the deletion of the 12 volt power supply to the expansion connector, the computer was compatible with the previous generation. The removal of the 12V power supply crippled some peripherals such as the original floppy disk controller, which then needed to be upgraded, installed in a Multi-Pak interface, or supplied with external power. The CoCo 2

10296-516: Was US$ 399 (equivalent to $ 1,480 in 2023). Within a few months, Radio Shack stores across the US and Canada began selling the new computer. The original version of the Color Computer sports a large silver-gray case with a calculator-like chiclet keyboard and was available with memory sizes of 4K (26-3001), 16K (26-3002), or 32K (26-3003). Versions with at least 16K of memory installed shipped with standard Microsoft Color Basic or (optionally) Extended Color BASIC . The only available connection to

10400-433: Was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are inefficient since drilling holes is expensive and consumes drill bits and

10504-426: Was further minimized and both flexible and rigid PCBs were incorporated in different devices. In 1995 PCB manufacturers began using microvia technology to produce High-Density Interconnect (HDI) PCBs. Recent advances in 3D printing have meant that there are several new techniques in PCB creation. 3D printed electronics (PEs) can be utilized to print items layer by layer and subsequently the item can be printed with

10608-460: Was introduced with its own new Disk BASIC ROM (v1.1). It adds a new command, DOS , to auto-boot software from disk (this requires a disk with a special boot sector ). This allows the use of software on copy protected disks or third-party operating systems, chiefly OS-9 . Production was partially moved to Korea, with production in the US and Korea happening in parallel using the same part numbers. Around March 1984, Radio Shack began advertising

10712-413: Was released with the original 4k TRS-80 Color Computer in 1980. It resides on 8k bytes of ROM, and is responsible for all 'housekeeping' duties on the system. This includes hardware initialization, memory management , interrupt processing, etc. Like most implementations of BASIC, each line of code starts with a line number and consists of one or more statements with variables and operators. 16k of memory

10816-634: Was sold in 16K and 64K models. 16K models use 16Kx1 DRAMs, but the chips are not the common 4116; they were instead 4517s (Radio Shack P/N 8040517), which use only +5V power rather than the triple voltages used by the 4116. 64K models use standard 4164 chips and have a control register at $ FFDE/$ FFDF to switch between the second 32K of RAM and the OS ROMs. With the ROMs banked out, the entire 64K of system RAM can be accessed. Upgraded BASIC ROMs add minor features and fix some bugs. A redesigned 5-volt disk controller

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