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90-494: BinHex was originally written in 1981 by Tim Mann for the TRS-80 as a standalone version of an encoding scheme originally built into a popular terminal emulator , ST80-III by Lance Micklus . BinHex was used for sending files via major online services , such as CompuServe , which were not "8-bit clean" and required ASCII armoring to survive. Not everyone used ST-80, however, so Mann wrote BinHex to allow users of other terminals to use

180-663: A Zilog Z80 processor clocked at 1.78 MHz (later models shipped with a Z80A). The initial Level I machines shipped in late 1977-early 1978 have only 4 KB of RAM. After the Expansion Interface and Level II BASIC were introduced in mid-1978, RAM configurations of 16 KB and up were offered (the first 16 KB was in the Model ;I itself and the remaining RAM in the Expansion Interface). The OS ROMs , I/O area, video memory, and OS work space occupy

270-564: A voice synthesizer , or a VOXBOX voice recognition unit. Originally, printing with the Model I required the Expansion Interface, but later Tandy made an alternative parallel printer interface available. The Model I Expansion Interface is the most troublesome part of the TRS-80 Model I system. It went through several revisions. The E/I connects to the CPU/keyboard with a 6-inch ribbon cable which

360-439: A "debounce" delay to the keyboard driver to avoid the noisy switch contacts. Tandy's KBFIX utility, the Model III, the last Model I firmware, and most third-party operating systems also implement the software fix, and Tandy changed the keyboard during the Model III's lifetime to an Alps Electric design with sealed switches. The Alps keyboard was available as an upgrade for the Model I for $ 79. The keyboard

450-496: A $ 100 deposit. Despite the internal skepticism, Radio Shack aggressively entered the market. The company advertised " The $ 599 personal computer " as "the most important, useful, exciting, electronic product of our time". Kornfeld stated when announcing the TRS-80, "This device is inevitably in the future of everyone in the civilized world—in some way—now and so far as ahead as one can think", and Tandy's 1977 annual report called

540-463: A better job, and Texas did not have a state income tax . Hired for his technical and retail experience, Leininger began working with French in June 1976. The company envisioned a kit, but Leininger persuaded the others that because "too many people can't solder", a preassembled computer would be better. Tandy had 11 million customers that might buy a microcomputer, but it would be much more expensive than

630-399: A capacity of 180 kilobytes per single-sided floppy disk. The use of index-sync means that a " flippy disk " requires a second index hole and write-enable notch. One could purchase factory-made "flippies". Some software publishers formatted one side for Apple systems and the other for the TRS-80. The usual method of connecting floppy drives involves setting the drive letter via jumper blocks on

720-451: A double-density disk controller (based on the WD 1791 chip) were made by Percom (a Texas peripheral vendor), LNW, Tandy, and others. The Percom Doubler adds the ability to boot and use double density floppies using a Percom-modified TRSDOS called DoubleDOS. The LNDoubler adds the ability to read and write 5 + 1 ⁄ 4 -inch (130 mm) diskette drives with up to 720 KB of storage, and also

810-419: A full-stroke QWERTY keyboard, 4 KB dynamic random-access memory (DRAM) standard memory, small size and desk area, floating-point Level I BASIC language interpreter in read-only memory (ROM), 64-character-per-line video monitor , and a starting price of US$ 600 (equivalent to US$ 3,000 in 2023). A cassette tape drive for program storage was included in the original package. While the software environment

900-492: A green-on-black display. Complaints about the video display quality were common. As Green wrote, "hells bells, [the monitor] is a cheap black and white television set with a bit of conversion for computer use". (The computer could be purchased without the Radio Shack monitor.) CPU access to the screen memory causes visible flicker . The bus arbitration logic blocks video display refresh (video-RAM reads) during CPU writes to

990-535: A hardware problem that complicated loading programs from cassette recorders. Tandy offered a small board which was installed at a service center to correct the issue. The ROMs in later models were modified to correct this. Only the Model I uses an Expansion Interface; all later models have everything integrated in the same housing. The TRS-80 does not use the S-100 bus like other early 8080 and Z80-based computers. A proprietary Expansion Interface (E/I) box, which fits under

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1080-488: A higher retail price to provide Tandy's typical profit margin. In February 1977 they showed their prototype, running a simple tax-accounting program, to Charles Tandy , head of Tandy Corporation. The program quickly crashed as the computer's implementation of Tiny BASIC could not handle the US$ 150,000 figure that Tandy typed in as his salary, and the two men added support for floating-point math to its Level I BASIC to prevent

1170-402: A home computer that could "do a payroll for up to 15 people in a small business, teach children mathematics, store your favorite recipes or keep track of an investment portfolio. It can also play cards." Six sacks of mail arrived at Tandy headquarters asking about the computer, over 15,000 people called to purchase a TRS-80—paralyzing the company switchboard—and 250,000 joined the waiting list with

1260-502: A loss of reliability on their tape recorders. With the Model III and improved electronics in the cassette interface, the standard speed increased to 1,500 baud which works reliably on most tape recorders. For loading and storing data from tape, the CPU creates the sound by switching the output voltage between three states, creating crude sine wave audio. The first version of the Model I also has

1350-549: A problem on the Mac, however, as there was still the need to encode the two forks into one. A team effort among Macintosh communications programmers, including Lempereur, resulted in MacBinary . These .bin files left the contents of the forks in their original 8-bit format and added a simple header for combining them on reception; MacBinary files were thus much smaller than BinHex. Lempereur released BinHex 5.0, almost identical to 4.0 with

1440-464: A range of peripherals and software for the TRS-80, began shipping computers by September, opened its first computer-only store in October, and delivered 5,000 computers to customers by December. Still forecasting 3,000 sales a year, Radio Shack sold over 10,000 TRS-80s in its first one and a half months of sales, 55,000 in its first year, and over 200,000 during the product's lifetime; one entered

1530-467: A recurrence. The project was formally approved on 2 February 1977; Tandy revealed that he had already leaked the computer's existence to the press. When first inspecting the prototype, he remarked that even if it did not sell, the project could be worthy if only for the publicity it might generate. MITS sold 1,000 Altairs in February 1975 and was selling 10,000 a year. When Charles Tandy asked who would buy

1620-467: A single object, so dragging it to a floppy disk in the Finder would copy both forks. This presented a serious problem when the file had to be stored on other computer systems. Those systems, unaware of the fork concept, would have to store the two forks as separate files. This presented the possibility that the two would be separated at some point, or not properly recombined when they were transmitted back to

1710-440: A software company, and the company had rejected his attempt for a Tandy Computer Center to sell non-Tandy computers. while the company's computer success helped Roach become Tandy's CEO. Selling computers did not change the company's "schlocky" image; the Radio Shack name embarrassed business customers, and Tandy executives disliked the "Trash-80" nickname for its products. By 1984, computers accounted for 35% of sales, however, and

1800-488: A standard feature of many commercial programs. They accept an "asterisk parameter", an asterisk (star) character typed following the program name when the program is run from the TRSDOS Ready prompt. When used following a spontaneous reboot (or an accidental reset, program crash, or exit to TRSDOS without saving data to disk), the program loads without initializing its data area(s), preserving any program data still present from

1890-410: A way similar to the way in which Base64 does. Number 0–63 are given characters according to the following list !"#$ %&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ[`abcdefhijklmpqr When encoding, a <return> should be inserted after every 64 characters. After encoding, a colon is placed before and after the data. TRS-80 The TRS-80 Micro Computer System ( TRS-80 , later renamed

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1980-400: Is memory-mapped so that certain locations in the processor's memory space correspond to the status of a group of keys. The color of the 12 in (300 mm) KCS 172 RCA monitor's text is faintly blue (the standard P4 phosphor used in black-and-white televisions). Green and amber filters, or replacement tubes to reduce eye fatigue were popular aftermarket items. Later models came with

2070-413: Is 64. This can be worked around by deleting the unused bit and piggybacking an eighth 2102 chip onto another. The alphanumeric symbols are displayed in 5×7 matrices of pixels . The 1978 manual for the popular word processor Electric Pencil came with instructions for modifying the computer. Although the modification needs to be disabled for Level II BASIC, its design became the industry standard and

2160-409: Is a continuous loop tape drive, dubbed the stringy floppy or ESF. It requires no Expansion Interface, plugging directly into the TRS-80's 40-pin expansion bus, is much less expensive than a floppy drive, can read and write random-access data like a floppy drive unlike a cassette tape, and it transfers data at up to 14,400 baud . Exatron tape cartridges store over 64 KB of data. The ESF can coexist with

2250-425: Is ignored, and the eighth toggles graphics mode. The reason that the seventh bit is ignored is due to the company's decision to have only seven 2102 static-RAM chips installed on the computer's motherboard instead of eight to keep the manufacturing cost low. Thus, there are no lowercase letters in the TRS-80 character set of an unmodified Model I, and the number of both graphics symbols and alphanumeric symbols

2340-783: Is jumpered to their number on the chain, or even an IBM PC "twist" cable, which requires setting each drive number to 1, but only permits two drives on the chain. Although third-party DOSes allow the user to define virtually any floppy format wanted, the "lowest common denominator" format for TRS-80s is the baseline single-density, single-sided, 35-40 track format of the Model I. Third-party vendors like Aerocomp made available double-sided and 80 track 5 + 1 ⁄ 4 -inch and later 3 + 1 ⁄ 2 -inch floppy drives with up to 720 KB of storage each. These new drives are half-height and therefore require different or modified drive housings. An alternative to cassette tape and floppy disk storage from Exatron sold over 4,000 units by 1981. The device

2430-504: Is present in Drive 0, it hangs there until the user either presses RESET on the back of the computer, which causes it to attempt to boot the disk again, or Break + Reset was pressed, which drops the computer into BASIC. Due to the above-mentioned problems with potentially corrupting disks, it is recommended to power up to the garbage screen with the disk drives empty, insert a system disk, and then hit RESET . InfoWorld compared

2520-422: Is to be ignored. The rest of the file consists of three parts, a header (containing file name, size etc.), a data fork (containing the file data) and a resource fork . Each has a two-byte CRC checksum. Everything except the (This file ... line is then seen as an area of binary data, which is encoded to ASCII characters. The encoding algorithm says that three bytes input are divided into four 6-bit values, in

2610-470: Is unreliable, partly because the interface lacked an external data separator (buffer). The early versions of TRSDOS were also buggy, and not helped by the Western Digital FD1771 chip which cannot reliably report its status for several instruction cycles after it receives a command. A common method of handling the delay was to issue a command to the 1771, perform several "NOP" instructions, then query

2700-405: Is unshielded against RF interference and its card edge connector tends to oxidize due to its base metal contacts. This demands periodic cleaning with a pencil eraser in order to avoid spontaneous reboots, which contributes to its "Trash-80" sobriquet. Aftermarket connectors plated with gold solved this problem permanently. Software developers also responded by devising a recovery method which became

2790-472: Is used to depress the power button and the E/I has no power LED, making it difficult to determine if it is running or not. The expansion unit requires a second power supply, identical to the base unit power supply. An interior recess holds both supplies. The user is instructed to power on and power off all peripherals in proper order to avoid corrupting data or potentially damaging hardware components. The manuals for

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2880-469: The Model I to distinguish it from successors) is a desktop microcomputer developed by American company Tandy Corporation and was sold through their Radio Shack stores. Launched in 1977, it is one of the earliest mass-produced and mass-marketed retail home computers . The name is an abbreviation of Tandy Radio Shack, Z80 [microprocessor] , referring to its Zilog Z80 8-bit microprocessor. The TRS-80 has

2970-661: The Smithsonian 's National Museum of American History . By mid-1978 the waits of two months or more for delivery were over, and the company could state in advertisements that TRS-80 was "on demonstration and available from stock now at every Radio Shack store in this community!" The first units, ordered unseen, were delivered in November 1977, and rolled out to the stores the third week of December. The line won popularity with hobbyists, home users, and small businesses. Tandy Corporation's leading position in what Byte magazine called

3060-537: The US$ 30 median price of a Radio Shack product, and a great risk for the very conservative company. Executives feared losing money as Sears did with Cartrivision , and many opposed the project; one executive told French, "Don't waste my time—we can't sell computers." As the popularity of CB radio —at one point comprising more than 20% of Radio Shack's sales—declined, however, the company sought new products. In December 1976 French and Leininger received official approval for

3150-487: The Western Digital 1771 single-density floppy disk controller chip. The industry standard Shugart Associates SA-400 minifloppy disk drive was used. Four floppy drives can be daisy-chained to the Model I. The last drive in the chain is supposed to have a termination resistor installed but often it is not needed as it is integrated into later cables. Demand for Model I drives greatly exceeded supply at first. The drive

3240-578: The World Wide Web , and electronic mail . The documents can also be stored on computers that run operating systems with no HFS support, such as Unix or Windows . MacBinary was widely supported on the Macintosh and was built into most communications programs on that platform. Similar solutions were built into most data compression applications on the Mac, and although these did not require MacBinary to survive transmission across non-Mac systems, MacBinary

3330-599: The cable spaghetti connecting the TRS-80 Model I's various components to the snakes in Raiders of the Lost Ark . Radio Shack offered a "TRS-80 System Desk" that concealed nearly all the cabling. It can accommodate the complete computer system plus up to four floppy drives and the Quick Printer. Since the cable connecting the Expansion Interface carries the system bus, it is short (about 6 inches). The user has no choice but to place

3420-732: The "1977 Trinity" ( Apple Computer , Commodore , and Tandy) had much to do with Tandy's retailing the computer through more than 3,000 of its Radio Shack storefronts in the USA. Tandy claimed it had "7000 [Radio Shack] stores in 40 countries". The pre-release price for the basic system (CPU/keyboard and video monitor) was US$ 500 and a US$ 50 deposit was required, with a money-back guarantee at time of delivery. By 1978, Tandy/Radio Shack promoted itself as "The Biggest Name in Little Computers". By 1979 1,600 employees built computers in six factories. Kilobaud Microcomputing estimated in 1980 that Tandy

3510-506: The 1771 for the result. Early TRSDOS neglects the required yet undocumented wait period, and thus false status often returns to the OS, generating random errors and crashes. Once the 1771 delay was implemented, it was fairly reliable. In 1981, Steve Ciarcia published in Byte the design for a homemade, improved expansion interface with more RAM and a disk controller for the TRS-80. A data separator and

3600-569: The BASIC/S compiler, which ran much faster than Mann's interpreted version. BinHex files of the era were typically given the file extension .hex . Ports soon appeared for other popular platforms of the era, including the Apple II . CompuServe later added support for 8-bit transfers, and the format quickly disappeared. The file upload problem still existed on CompuServe when the Mac was first released in 1984. In April 1984, William Davis ported BinHex to

3690-589: The CTR-41 unit with the CTR-80 which had built-in AGC circuitry (and no volume control). This helped the situation, but tape operation is still unreliable. TRS-80 Model I computers with Level I BASIC read and write tapes at 250 baud (about 30 bytes per second); Level II BASIC doubles this to 500 baud (about 60 bytes per second). Some programmers wrote machine-language programs that increase the speed to up to 2,000 bits per second without

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3780-460: The E/I directly behind the computer with the monitor on top. This causes problems for a non-Tandy monitor whose case did not fit the mounting holes. Also, the friction fit of the edge connector on the already short interconnect cable makes it possible to disconnect the system bus from the CPU if either unit is bumped during operation. Radio Shack introduced floppy drives in July 1978, about six months after

3870-721: The Mac using Microsoft BASIC to produce a version that was largely identical to the TRS-80 versions of the same era. This version only supported encoding of the "data fork", ignoring the resource fork , which meant it could only be used for data files. The rise in use of Internet e-mail coincided roughly with the release of the Macintosh, and Davis's version was posted on the Info-Mac mailing list by Joel Heller in June 1984. Several newer versions were published during 1984, resulting in BinHex 3 that could encode both forks. Yves Lempereur, author of

3960-406: The Mac. This problem led to a number of solutions that combined the two forks together into a single file, and then automatically pulling them back apart when they reached another Mac. MacBinary was one of the most popular solutions, although BinHex was also used on UseNet , where data transfer was not 8-bit clean . Apple's own solutions, AppleSingle and AppleDouble , were never widely adopted in

4050-431: The Model I went on sale. The Model I disk operating system TRSDOS was written by Randy Cook under license from Radio Shack; Randy claimed to have been paid $ 3000 for it. The first version released to the public was a buggy v2.0. This was quickly replaced by v2.1. Floppy disk operation requires buying the Expansion Interface, which included a single-density floppy disk interface (with a formatted capacity of 85K) based on

4140-445: The Model III launch in mid-1980, Tandy stated that the Model I was still sold, but it was discontinued by the end of the year. Tandy cited one of the main reasons as being the prohibitive cost of redesigning it to meet stricter FCC regulations covering the significant levels of radio-frequency interference emitted by the original design. The Model I radiated so much interference that, while playing games, an AM radio placed next to

4230-472: The Model III was succeeded by the compatible TRS-80 Model 4 . Following the original Model I and its compatible descendants , the TRS-80 name became a generic brand used on other unrelated computer lines sold by Tandy, including the TRS-80 Model II , TRS-80 Model 2000 , TRS-80 Model 100 , TRS-80 Color Computer , and TRS-80 Pocket Computer . In the mid-1970s, Tandy Corporation 's Radio Shack division

4320-406: The TRS-80 advise turning on the monitor first, then any peripherals attached to the E/I (if multiple disk drives are attached, the last drive on the chain is to be powered on first and work down from there), the E/I, and the computer last. When powering down, the computer is to be turned off first, followed by the monitor, E/I, and peripherals. In addition, users are instructed to remove all disks from

4410-464: The TRS-80 data cassette drive. Exatron also made a complementary RAM expansion board that installed in the TRS-80 keyboard to increase memory to 48 KB without the EI. MacBinary MacBinary is a file format that combines the data fork and the resource fork of a classic Mac OS file into a single file, along with HFS's extended metadata . The resulting file is suitable for transmission over FTP ,

4500-492: The TRS-80 had the largest selection of software in the microcomputer market. Until 1982, the TRS-80 was the bestselling PC line, outselling the Apple II by a factor of five according to one analysis. The broadly compatible TRS-80 Model III was released in the middle of 1980. The Model I was discontinued shortly thereafter, primarily due to stricter Federal Communications Commission (FCC) regulations on radio-frequency interference to nearby electronic devices. In April 1983,

4590-610: The VRAM, causing a short black line. This has little effect on normal BASIC programs, but fast programs made with assembly language can be affected. Software authors worked to minimize the effect, and many arcade-style games are available for the Tandy TRS-80. Because of bandwidth problems in the interface card that replaced the TV's tuner, the display loses horizontal sync if large areas of white are displayed. A simple half-hour hardware fix corrects

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4680-453: The black-and-silver colors of the RCA CRT unit's cabinet for the TRS-80 units as well. Having spent less than US$ 150,000 on development, Radio Shack announced the TRS-80 (Tandy Radio Shack) at a New York City press conference on August 3, 1977. It cost US$ 399 (equivalent to $ 2,000 in 2023), or US$ 599 (equivalent to $ 3,000 in 2023) with a 12" monitor and a Radio Shack tape recorder;

4770-405: The business" and "never our large market". Although the press conference did not receive much media attention because of a terrorist bombing elsewhere in the city , the computer received much more publicity at Boston University 's Personal Computer Fair two days later. A front-page Associated Press article discussed the novelty of a large consumer-electronics company selling

4860-476: The cassette port and plugging an amplifier into the cassette "Mic" line. Most games use this ability for sound effects. An adapter was available to use Atari joysticks . User data was originally stored on cassette tape . Radio Shack's model CTR-41 cassette recorder was included with the US$ 599 package. The software-based cassette tape interface is slow and erratic; Green described it as "crummy ... drives users up

4950-577: The company had 500 Tandy Radio Shack Computer Centers. By 1979, when Radio Shack launched the business-oriented, and incompatible, TRS-80 Model II , the TRS-80 was officially renamed the TRS-80 Model I to distinguish the two product lines. After some exhibitors at the 1979 Northeast Computer Show were forced to clarify that their products bearing the TRS-80 name were not affiliated with Radio Shack, publications and advertisers briefly began to use "S-80" generically rather than "TRS-80" under scare of legal action, though this never materialized. Following

5040-447: The computer "probably the most important product we've ever built in a company factory". Unlike competitor Commodore —which had announced the PET several months earlier but had not yet shipped any—Tandy had its own factories (capable of producing 18,000 computers a month) and distribution network, and even small towns had Radio Shack stores. The company announced plans to be selling by Christmas

5130-418: The computer can be used to provide sounds. Radio Shack offered upgrades (double-density floppy controller, LDOS, memory, reliable keyboard with numeric keypad, lowercase, Level II, RS-232C) as late as its 1984 catalog. The Model I combines the mainboard and keyboard into one unit, which became a design trend in the 8-bit microcomputer era, although the Model I has a separate power supply unit. It uses

5220-576: The computer, company president Lewis Kornfeld admitted that they did not know if anyone would, but suggested that small businesses and schools might. Knowing that demand was very strong for the US$ 795 Altair—which cost more than $ 1,000 with a monitor—Leininger suggested that Radio Shack could sell 50,000 computers, but no one else believed him; Roach called the figure "horseshit", as the company had never sold that many of anything at that price. Roach and Kornfeld suggested 1,000 to 3,000 per year; 3,000

5310-448: The contents of a BinHex file, one will notice that it has a message usually on the first line identifying it as BinHex, followed by many 64-character lines made up of seemingly random letters, numbers, and punctuation marks. Here is a sample of what BinHex actually looks like: There must be a text line, which is used by users and tools to recognize BinHex versions: (This file must be converted with BinHex 4.0) . Any text before this line

5400-401: The data. Then it is halted to rewind the tape and restart the load. Users were instructed to save multiple copies of a software program file, especially if audio tape cassettes instead of certified data tape was used. Automatic gain control or indicator circuits can be constructed to improve the loading process (the owner's manual provides complete circuit diagrams for the whole machine, including

5490-463: The drive controller board, but Tandy opted for a slightly more user-friendly technique where all four select pins on the drives are jumpered and the ribbon cable is missing the Drive Select line. Thus, the user does not need to worry about moving jumpers around depending on which position on the chain a drive was in. A standard flat floppy ribbon cable is usable on the Model I, in which case the drives

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5580-407: The drives during power up or down (or else leave the drive door open to disengage the read/write head from the disk). This is because a transient electrical surge from the drive's read/write head would create a magnetic pulse that could corrupt data. This was a common problem on many early floppy drives. The E/I displays a screen full of garbage characters on power up and unless a bootable system disk

5670-511: The exception that it used MacBinary to combine the forks before running the 8-to-6 encoding. This saw little use, as he expected. On the Internet , e-mail was still the primary method of moving files. At the time, relatively few people had full access to the Internet, and services like FTPmail were the only way many users could download files. Years later when he first got onto the Internet, Lempereur

5760-410: The fact that the metadata information in the header was in plain text and thus could be corrupted in the same way as the data. In order to solve all of these problems, Lempereur released BinHex 4.0 in 1985, skipping 3.0 to avoid confusion with the now long-dead BASIC version. 4.0 first combined the data fork, resource fork and file metadata into a common 8-bit format, ran run-length encoding (RLE) on

5850-447: The first assembler for the Mac, MacASM, found that in order to upload his files to CompuServe he had to use BinHex. The BASIC version was very slow, so Lempereur ported BinHex 3 to assembler and released it as BinHex 1.0. The program was roughly a hundred times as fast as the BASIC version, and soon upgrade requests were flooding in. The original BinHex was a fairly simple format, one that

5940-554: The first 16 KB of memory space on the Model I. The remaining 48 KB of the 64 KB memory map space is available for program use, subject to the amount of physical RAM installed. Although the Z80 CPU can use port-based I/O, the Model I's I/O is memory-mapped aside from the cassette tape and RS-232 serial ports. The TRS-80 Model I keyboard uses mechanical switches that suffer from " keyboard bounce ", resulting in multiple letters being typed per keystroke. The problem

6030-472: The format. The original ST-80 system worked by converting the binary file contents to hexadecimal numbers, which were encoded as ASCII digits and letters ( 0 – 9 , A – F ). It then added a newline after every 60 characters. The system became very popular after Mann uploaded it to CompuServe's TRS-80 files area. The system quickly gained the addition of a checksum at the end of every line to check for errors. Bill Stockwell converted that version to

6120-404: The most expensive product Radio Shack previously sold was a US$ 500 stereo. The company hoped that the new computer would help Radio Shack sell higher-priced products, and improve its "schlocky" image among customers. Small businesses were the primary target market, followed by educators, then consumers and hobbyists; despite its hobbyist customer base, Radio Shack saw them as "not the mainstream of

6210-406: The new encoding was no longer hexadecimal in nature, the established name of the program was retained. The smaller files were incompatible with the older ones, so the extension became .hcx , c for compact. The new version replaced the earlier ones "overnight". Lempereur had concerns about some of the features of BinHex, notably its use of a checksum instead of a cyclic redundancy check (CRC) and

6300-519: The older 8-inch (200 mm) diskettes with up to 1,155 KB. Near the end of the Model I's lifespan in 1982, upgrades were offered to replace its original controller with a double-density one. The first disk drives offered on the Model I were Shugart SA-400s which supported 35 tracks and was the sole 5 + 1 ⁄ 4 -inch drive on the market in 1977–78. By 1979, other manufacturers began offering drives. Models 3/4/4P uses Tandon TM-100 40-track drives. The combination of 40 tracks and double density gives

6390-489: The peripheral interfaces, with notes on operation). An alternative to using tape was data transmissions from the BBC 's Chip Shop programme in the UK, which broadcast software for several different microcomputers over the radio. A special program was loaded using the conventional tape interface. Then the radio broadcast was connected to the cassette tape interface. Tandy eventually replaced

6480-428: The pre-reboot session. Thus, for example, if a VisiCalc user suffers a spontaneous reboot, to recover data the user enters V + C + SPACE + ✶ at TRSDOS Ready, and Visicalc restores the previous computing session intact. The power button on the E/I is difficult to operate as it is recessed so as to guard against the user accidentally hitting it and turning it off while in use. A pencil eraser or similar object

6570-402: The problem. The graphics are displayed at a resolution of 64×16 character positions on a screen measuring 7.5 inches (19 cm) wide and 6.625 inches (16.83 cm) tall. Each character is composed of a 2×3 matrix of pixels, and corresponds to one byte of the 1 KB video memory used by the TRS-80. In each of those bytes, the first six bits control which pixel is displayed. The seventh bit

6660-439: The project but were told to emphasize cost savings; for example, leaving out lowercase characters saved US$ 1.50 in components and reduced the retail price by US$ 5 . The original US$ 199 retail price required manufacturing cost of US$ 80 ; the first design had a membrane keyboard and no video monitor. Leininger persuaded Roach and French to include a better keyboard, a monitor, datacassette storage, and other features requiring

6750-400: The resource system had the significant limitation that the maximum size of any single resource was only 32 kB, far too small for storing document data. To address this, Apple introduced the concept of forks , allowing any file in the filesystem to have both a resource fork and a data fork. Physically these were separate files, but the OS would ensure the two separate files were always treated as

6840-422: The result to provide some compression, and then ran the 8->6 conversion on the result and protected everything with multiple CRCs. The resulting .hqx files were roughly the same size of the .hcx 's, but much more robust. At about the time BinHex 4 was released, most online services started supporting robust 8-bit file transfer protocols such as ZMODEM , and the need for ASCII armoring went away. This left

6930-516: The two men visited National Semiconductor in California in mid-1976, Homebrew Computer Club member Steve Leininger's expertise on the SC/MP microprocessor impressed them. National executives refused to provide Leininger's contact information when French and Roach wanted to hire him as a consultant, but they found Leininger working part-time at Byte Shop . Leininger was unhappy at National, his wife wanted

7020-639: The user community. Files encoded with MacBinary, regardless of the version, usually have a .bin or .macbin file extension appended to the ends of their filenames. E-mail programs such as Eudora can extract and decode MacBinary mail messages. Most dedicated FTP programs for the Mac, such as Fetch and Transmit , transparently decode MacBinary files they download. MacBinary is similar to BinHex , but MacBinary produces binary files as opposed to ASCII text. Thus, MacBinary files are smaller than BinHex files, but older applications and servers are more likely to corrupt them. The first incarnation of MacBinary

7110-461: The video monitor and serves as its base, was offered instead. Standard features of the E/I are a floppy disk controller, Centronics parallel port for a printer, and an added cassette connector. Optionally, an extra 16 or 32 KB of RAM can be installed and a daughterboard with an RS-232 port. The 40-conductor expansion connector passes through to a card edge connector, which permits the addition of external peripherals such as an outboard hard disk drive,

7200-401: The wall", and the first issue of 80 Micro has three articles on how to improve cassette performance. It is sensitive to audio volume, and the computer gives only a crude indication as to whether the correct volume was set, via a blinking character on screen while data is loaded. To find the correct volume at first use, the load is started and the volume is adjusted until the TRS-80 picked up

7290-464: Was a successful American chain of more than 3,000 electronics stores. Among the Tandy employees who purchased a MITS Altair kit computer was buyer Don French, who began designing his own computer and showed it to the vice president of manufacturing John V. Roach , Tandy's former electronic data processing manager. Although the design did not impress Roach, the idea of selling a microcomputer did. When

7380-525: Was described in Wayne Green 's editorial in the first issue of 80 Micro . Dirt, cigarette smoke , or other contamination enters the unsealed key switches, causing electrical noise that the computer detects as multiple presses. The key switches can be cleaned, but the bounce recurs when the keyboard is reexposed to the contaminating environment. Keyboard bounce only occurs in Model I computers with Level II BASIC firmware ; Level I BASIC has

7470-445: Was not very efficient because it expanded every byte of input into two, as required by the hexadecimal representation—an 8-to-4 bit encoding. For BinHex 2.0, Lempereur used a new 8-to-6 encoding that decreased file size by 50%. He also took the opportunity to expand the checksum from 8 to 16-bits. This new encoding used the first 64 ASCII printing characters, including the space, to represent the data, similarly to uuencode . Even though

7560-532: Was often added in these cases to preserve longer filenames and other features. The dual-fork nature of the HFS system was not used on Mac OS X , and MacBinary has largely disappeared. In contrast to other computers of the era, Macintosh applications included both computer code as well as a large number of resources that were used by the operating system (OS) itself. These resources were also widely used in documents to store rich media like sounds and images. However,

7650-514: Was released in 1985. The standard was originally specified by Dennis Brothers (author of the terminal program MacTEP and later an Apple employee), BinHex author Yves Lempereur, PackIt author Harry Chesley, et al. then added support for MacBinary into BinHex 5.0, using MacBinary to combine the forks instead of his own methods. Most terminal programs and internet utilities added built-in MacBinary support during this period as well. Two years later it

7740-492: Was selling three times as many computers as Apple Computer , with both companies ahead of Commodore. By 1981, InfoWorld described Radio Shack as "the dominant supplier of small computers". Hundreds of small companies produced TRS-80 software and accessories, and Adam Osborne described Tandy as "the number-one microcomputer manufacturer" despite having "so few roots in microcomputing". That year Leininger left his job as director for advanced research; French had left to found

7830-720: Was stable, the cassette load/save process combined with keyboard bounce issues and a troublesome Expansion Interface contributed to the Model I's reputation as not well-suited for serious use. Initially (until 1981), it lacked support for lowercase characters which may have hampered business adoption. An extensive line of upgrades and add-on hardware peripherals for the TRS-80 was developed and marketed by Tandy/Radio Shack. The basic system can be expanded with up to 48 KB of RAM (in 16 KB increments), and up to four floppy disk drives and/or hard disk drives . Tandy/Radio Shack provided full-service support including upgrade, repair, and training services in their thousands of stores worldwide. By 1979,

7920-419: Was surprised to find that BinHex 4.0 was still extremely popular. The same ends could be achieved by first using MacBinary or AppleSingle to combine the forks, and then using Uuencode or Base64 on the resulting file, but none of these solutions ever became popular and BinHex 4.0 survived well into the late 1990s. File archives of classic Mac OS software are still filled with BinHexed files. Looking at

8010-441: Was the quantity the company would have to produce to buy the components in bulk. Roach persuaded Tandy to agree to build 3,500—the number of Radio Shack stores—so that each store could use a computer for inventory purposes if they did not sell. RCA agreed to supply the video monitor—a black-and-white television with the tuner and speakers removed—after others refused because of Tandy's low initial volume of production. Tandy used

8100-460: Was widely sold in kit form, along with an eighth 2102 chip. Later models came with the hardware for the lowercase character set to be displayed with descenders. With higher-density RAM chips and purpose-built monitors, higher-resolution crisp displays are obtainable; 80×24-character displays are available in the Model II, Model 4, and later systems. The Model I has no built-in speaker. Square-wave tones can be produced by outputting data to

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