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66-796: The data rate was nominally 600 bit/s, but the simple error correction and short gaps between the resulting packets lowered this somewhat. In the end, its rate was roughly double that of the formats used by the Commodore Datasette or the TI-99/4 . In some markets, where the Program Recorder was the only cost-effective storage solution, software-based high-performance modes were developed that operated more than three times as fast, and as much as four times as fast with simple hardware modifications. The drives had several features not commonly found on other platforms. The system's device driver supported

132-462: A Shugart Associates SA-400 floppy drive. Steve Jobs went to Shugart and asked for a stripped-down drive mechanism for $ 100; Shugart responded by shipping them 25 prototypes of a new model they called the SA-390. Woz's controller then provided the bits that Shugart had removed, allowing two drives to be controlled by a single card. The resulting system operated at 15 kbps, making it faster than any of

198-456: A network packet is a formatted unit of data carried by a packet-switched network . A packet consists of control information and user data; the latter is also known as the payload . Control information provides data for delivering the payload (e.g., source and destination network addresses , error detection codes, or sequencing information). Typically, control information is found in packet headers and trailers . In packet switching ,

264-446: A tachometer that finally solved the speed problems. It also replaced a number of components in an effort to improve reliability. The original MPI mechanisms used a unique drive door mechanism. The door slid vertically and was sprung to hold it normally open, in the upper position, revealing the drive slot behind it. A handle-like extension on the front of the door allowed the user to pull it down to close it, which latched when reaching

330-536: A Chelco mechanism and another using Sanyo . They can be distinguished by the colored sticker inside the drive bay, Chelco used silver while Sanyo was orange. When the XE series were released they were initially sold into existing markets and Atari introduced a number of XE-styled accessories to go with them. This led to the introduction of the XC11 in the UK around 1986, which are essentially

396-460: A new drive from Atari within the next half year". This prediction came true; when the 1200XL finally reached the market in June 1983, it was accompanied by the new Atari 1050 . It offered the new "enhanced" or "dual density" option that improved formatted capacity to 130 kB, although it was some time before DOS was upgraded to support it. The 1050 quickly replaced the 810 in the market. The 810 case

462-474: A number of interfaces that allowed any third party cassette deck to be used. The Atari 8-bit computers featured an advanced (for the era) input/output system, Atari SIO . Devices normally had in and out ports that allowed a number of devices to be daisy-chained together into a single port on the host computer. Most devices were "smart", listening for commands being sent through the data stream for instructions pertaining it its own device number. For instance,

528-402: A number of small programs, like Snail and Drive RPM, that would test the speed of the drive in software in order to aid the user in adjusting it back to 288. Initial units shipped with Atari DOS 1.0, sometimes known as DOS I. This was replaced by DOS 2.0S in 1981. While the 8-bit machines were first being introduced, the first MFM double-density drive controllers were appearing, allowing

594-563: A packet-based format with checksums for error detection, as opposed to lacking any error detection or using whole-file checksums. The driver included separate formats for binary data and more complex data that required longer to process it. The left audio channel could be used to send audio through to the television speaker, which could be used to provide music during the loading period, or in program-controlled computer aided instruction systems. The original 400 and 800 models, released in 1979, were housed in robust beige colored plastic cases and

660-431: A potential entry into the education market, forming an educational arm and producing a series of tapes early in the system's history. Best known among these was States and Capitals , a simple quiz game that became the topic of several of Atari's television ads. The basic signaling rate of the system was 600 bit/s, but there was some additional overhead due to the inter-record gaps and the packet structure. This reduced

726-401: A series of computer peripherals were released to match this design. The original 410 was a modified Sears model 799.21672500 Solid State Cassette Recorder with a Japanese mechanism by Bigston. It was a relatively large unit and was unique among the line in that it featured a metal carrying handle that slid out from the front of the unit, identical to its Sears counterpart. This was replaced by

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792-547: A short bit of mark tone, 5327 Hz. The associated program would then turn on the MOTOR line to begin playback and then read data until it saw a series of ones on the POKEY. At this point the program would stop the cassette again and interact with the user. This was typically used to stop and ask multiple-choice questions before proceeding to the next section of audio. Atari saw the CAI market as

858-555: A short note on ways to improve the reliability of reading data from the decks. A fuller treatment appeared in Antic in February 1984. This involved replacing two resistors, one each in both the high and low-frequency filters. This reduces the width of their bell-curve-shaped frequency response and eliminates any overlap where a signal might produce output in both channels. Network packet In telecommunications and computer networking ,

924-422: A single checksum byte at the end, so the overall packet was 132 bytes long. The first two bytes were 01010101 01010101, used for clock recovery by the POKEY to address tape stretch and other common problems in cassette systems. The next byte, the control byte, specified if the packet had a complete 128 bytes of data, less than that, or was a special end-of-file (EOF) marker. Only the packet immediately preceding

990-559: A single drive. This was enforced by leaving off the daisy-chaining port on the tape decks, forcing it to be the last device on the SIO chain. The exception was the 1010, which included a second port and did allow chaining. The system used frequency-shift keying (FSK) to store data on the tapes. When being used to write data, the POKEY chip was set up with one of its four channels producing 5327 Hz for mark and another to 3995 Hz for space, while

1056-454: A somewhat smaller and more rounded unit around 1981 using a new mechanism from Transtek or Chelco Sound in Hong Kong . The release of the 600XL and 800XL in 1983 led to the system being repackaged in a much smaller form, the 1010. The new model used the black/white/silver styling of the new machines and was assigned a number in the new 1000-series device numbers. Two versions were made, one using

1122-527: A television; instead, a 3rd party sold the required RF modulator and thus Apple didn't need testing. Atari was determined to make a plug-and-play system that connected directly to the television, like the Atari VCS . This precluded the idea of having expansion slots that could be connected to external equipment, like on the Apple, as the openings would be difficult to shield property to avoid RF leakage. This led to

1188-401: A third channel was set to 600 Hz and used as a clock. Data sent to the cassette device driver toggled which of the two tones was played to DATAOUT while being timed by the clock. Each byte was prefixed by a space bit and postfixed by a mark. Reading was accomplished by two narrowband filters in the drive itself, which produced output when the corresponding tone was heard. During playback,

1254-429: A total of 720 sectors per disk. Each sector held 128 bytes, for a total storage of 92,160 bytes/disk (90 kB). Later models with the C ROM, and a number of third party upgrades, used a staggered sector layout to reduce seek time and improve read performance as much as 30% over the original layout. The drive ignored the alignment hole, and thus did not need the two-hole "flippy disk" to use the second side. It did respect

1320-497: Is often carried as the payload inside an Ethernet frame, which has its own header and trailer. Per the end-to-end principle , IP networks do not provide guarantees of delivery, non-duplication, or in-order delivery of packets. However, it is common practice to layer a reliable transport protocol such as Transmission Control Protocol on top of the packet service to provide such protection. The Consultative Committee for Space Data Systems ( CCSDS ) packet telemetry standard defines

1386-508: Is the official floppy disk drive for the Atari 400 and 800, the first two models of Atari 8-bit computers . It was released by Atari, Inc. in 1980. The single-density drive provides 90 kB of storage. The 810 has a data transfer rate of 6 kbps in most cases and a number of reliability issues. Third-party enhancements such as the Happy 810 address these problems, as do replacement drives like

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1452-478: The Atari 810 floppy disk drive included a MOS 6507 that watched for commands being sent to a device number selected using switches on the back of the drive. The cassette drive was intended to be a much lower-cost device and this eliminated the possibility of it being smart. Instead, and in contrast to any other devices used with SIO, the cassette system used several dedicated pins in the SIO port that directly controlled

1518-503: The Indus GT with more storage and other features. At the same time as the 810, Atari announced the double-density Atari 815 , allowing 180 kB per disk, with two drives in one case. It was never put into full production and only small numbers reached the market. The 810 was replaced by the Atari 1050 with the release of the XL series machines in 1983. The 1050 was replaced in turn in 1987 by

1584-621: The NICAM signal is transmitted on a subcarrier alongside the sound carrier. This means that the FM or AM regular mono sound carrier is left alone for reception by monaural receivers. The NICAM packet (except for the header) is scrambled with a nine-bit pseudo-random bit-generator before transmission. Making the NICAM bitstream look more like white noise is important because this reduces signal patterning on adjacent TV channels. Atari 810 The Atari 810

1650-585: The XF551 with a double-sided, double-density 360 kB mode. The machines that emerged as the Atari 8-bit computers had originally been designed as part of a project to develop a driver chipset for a new games console . During the time the chips were being developed, the Apple II became very popular and propelled Apple Computer into one of the largest initial public offerings of its era. Atari, recently purchased by Warner Communications , had placed Ray Kassar in

1716-430: The bandwidth of the transmission medium is shared between multiple communication sessions, in contrast to circuit switching , in which circuits are preallocated for the duration of one session and data is typically transmitted as a continuous bit stream . In the seven-layer OSI model of computer networking , packet strictly refers to a protocol data unit at layer 3, the network layer . A data unit at layer 2,

1782-399: The data link layer , is a frame . In layer 4, the transport layer , the data units are segments and datagrams . Thus, in the example of TCP/IP communication over Ethernet , a TCP segment is carried in one or more IP packets , which are each carried in one or more Ethernet frames . The basis of the packet concept is the postal letter: the header is like the envelope, the payload is

1848-532: The 6507 running at 500 kHz with a standard FM encoding drive controller, the Western Digital FD1771 . Despite these efforts to lower cost, the resulting drive was still more expensive than the Disk II, listed at $ 599 when it was introduced in 1979. It also had the disadvantage of running more slowly than the Disk II; although the underlying SIO bus was running at 19.2 kbps, the effective data rate

1914-531: The Apple II. The performance and reliability problems with the 810 also led to a thriving market for third-party drives like the Rana 1000 and Indus GT , along with a wide selection of replacements for Atari DOS. Combining one of these drives with a replacement DOS offered higher performance and often true double-density support. As the double-density format had been set with the 815 in 1980, these drives used that format as

1980-587: The CEO position in March 1978. He decided to redirect the chipset to the emerging home computer market to take on Apple. One of the key reasons for the Apple II 's success was the Disk II , introduced in June 1978 at the very low (for the era) price of $ 495 (equivalent to $ 2,312 in 2023) plus the interface card. The interface was based on a system Steve Wozniak had previously built while working at Hewlett-Packard to control

2046-555: The EOF could be in the shorter format, with the number of used bytes placed in the byte preceding end-of-packet checksum. Both the short packet and EOF packet were padded out to a full 132 bytes long. Between packets, the system played the mark tone continually, with a short Pre-Record Write Tone and a variable length Post-Record Gap, the two combined known as the InterRecord Gap (IRG). The driver supported two writing modes. In Short IRG mode,

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2112-462: The IRG was about 0.25 seconds long. This mode was used for most transfers, leaving just enough time for the computer to calculate the checksum and potentially stop the drive if the checksum failed. The other mode, Normal IRG, played a 3 second gap between packets. This time was selected to ensure that the drive could be stopped and restarted without it having advanced past the next packet. Normal IRG

2178-483: The SIO communications could be easily doubled. It was later revealed that the speed was not a limitation of the SIO port, but the maximum speed of the logic analyzer available in the lab where it was being developed. Best known among the many products was the Happy 810 , introduced in 1982. It added a buffer able to cache one entire track of data, and along with the associated Warp Speed software, increased read performance about three times, making it very competitive with

2244-540: The Short IRG. The system lacked any sort of defined file format for general purpose files, but it did define a file format for bootable cassettes. This consisted of a single extra packet at the start of the file, using only the first six bytes of the payload and filling the rest of the packet with zeros. The first of these bytes was unused filler. The second byte held the number of packets in the file, allowing up to 255 packets, or 32 kB of data. The next two bytes specified

2310-520: The VCS production line as the basis for the interface. Atari purchased large numbers of 6507s from Synertek that were officially rated for operation at 1 MHz, but most of them were being able to run at a slightly higher 1.1 MHz that the VCS worked at. Those that did not, a small proportion of the chips, were simple warehoused at Atari. As they had already been paid for, and were essentially free, they were perfect for use as low-cost microcontrollers like

2376-571: The XL12 and XC13, sold in Poland, the Czech Republic and Slovakia . All of the versions were mechanically similar. They all used a flip-up door on the top for inserting a tape. A piece of bright orange or silver tape behind the tape window was used make the current position of the tape more visible. The 410 had a power plug and internal power supply, the 1010 used an external power supply and ring-jack plug on

2442-518: The back of the case, and the XC12 and later models were powered through the SIO cable. The 1010 added a red LED to the front to indicate power-on, while the XC12 lacked the power LED but added one on top that lit while writing. Several other companies produced compatible drives for the Atari machines, notably General Electric 's Compu-Mate Computer Data Recorder, the Taihaho Computer Cassette and

2508-537: The basis for their disks as well. In April 1982, Atari began the process of designing improved versions of the 8-bit series, then referred to as the Sweet 8 and Sweet 16. Changes to the plans led to only one of these designs being released as the 1200XL. Containing "no true innovations", the most notable change was the introduction of a new design language from Regan Cheng using off-white and black plastics will brushed metal overlay on switches and other fixtures. This led to

2574-464: The bottom of its travel. A button unlocked the door, causing it to flip open. In November 1982, the drive mechanism switched from MPI to a new mechanism from Tandon , which was known as the "810T Analog". The main external difference was that the former push-and-lift door was replaced by a simpler turn-to-open latch. The drive was otherwise the same as the 810M. The disks were formatted with 40 tracks, or 48 tracks per inch, with 18 sectors per track, for

2640-460: The cassette was the only cost-effective storage medium, the performance of the system was a serious problem. This led to a wide variety of software and hardware upgrades to improve performance. Among the best known was the Turbo 2000 system from Czechoslovakia , which increased the basic data rate of an XC12 to 2270 bit/s, almost four times as fast as the original standard. In 1983, Carl Evens posted

2706-402: The channel and then played back through the television speaker. This was originally used with a series of computer aided instruction (CAI) cassettes that were sold by Atari and later by third parties. It was also sometimes used on bootable cassettes to provide music while the program loaded. When used for CAI, a simple protocol was used to control playback. Each section of audio was marked with

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2772-554: The competing designs of the era. The new Atari machines faced the problem that the Federal Communications Commission (FCC) had recently introduced standards to deal with the profusion of systems that connected to televisions that were causing significant problems with interference. The new rules were extremely strict, requiring a lengthy and costly testing suite to be run against any new product and anything that connected to it. Apple avoided this by not connecting to

2838-429: The drive number from 1 to 4. The drive saw a series of improvements over time. The original 810 had problems with speed regulation and also had marginal ability to distinguish between clock pulses and data on some disks. Starting on 1 September 1981, all new 810s were built to the "DS" standard, for "Data Separator", identifiable by a small sticker. These versions added an External Data Separator Board which plugged into

2904-428: The drive. These included pin 8, MOTOR, that turned the tape drive motor on and off, and pin 11, AUDIOIN, which passed through any audio recorded on the left audio channel into the system. Data was read and written to the right audio channel using the standard SIO data pins, pin 3, DATAIN and pin 5, DATAOUT. Because there was no way to decode commands or perform device selection, any single host computer could only support

2970-401: The effective rate somewhat, to perhaps 550 bit/s. This compares favorably to similar systems of the era, like the 300 bit/s Kansas City Standard or the formats used on the TI-99/4 or Commodore Datasette , which had similar signaling rates as Atari but wrote all data twice as an error correction mechanism and thus had effective rates closer to 300 bit/s. In those markets where

3036-482: The elementary stream between PES packet headers. A typical method of transmitting elementary stream data from a video or audio encoder is to first create PES packets from the elementary stream data and then to encapsulate these PES packets inside an MPEG transport stream (TS) packets or an MPEG program stream (PS). The TS packets can then be transmitted using broadcasting techniques, such as those used in an ATSC and DVB . In order to provide mono compatibility ,

3102-586: The entire content inside the envelope, and the footer would be your signature at the bottom. Network design can achieve two major results by using packets: error detection and multiple host addressing . Communications protocols use various conventions for distinguishing the elements of a packet and for formatting the user data. For example, in Point-to-Point Protocol , the packet is formatted in 8-bit bytes, and special characters are used to delimit elements. Other protocols, like Ethernet, establish

3168-571: The introduction of a new line of peripherals that matched the styling. Initially this included the Atari 1010 cassette deck , the Atari 1020 plotter, and 1025 printers. When the 1200XL was introduced at the Winter Consumer Electronics Show in December 1982, there was no sign of a new floppy drive. One reviewer noted that when he went looking all he could find was the "old model 810 clunkers", and speculated that "we will be seeing

3234-510: The introduction of the SIO serial bus , a system that allowed devices to be daisy chained to a single port. Using a cable made shielding to the required levels much easier, but also required the external devices to host the interface circuitry that would normally be placed on an expansion card inside the machine. This drove up the complexity and cost of the external devices. To offset this as much as possible, Atari used discarded MOS 6507 chips from

3300-523: The keyboard to indicate the drive was ready. The system would then assert the MOTOR line to begin playback, reading from the tape for up to 35 seconds looking for the header packet. If it was not found, or some other type of packet was found, an error was reported. Another feature of the Atari SIO port was the AUDIOIN pin, which was connected to the left channel of the cassette. This allowed audio to be recorded to

3366-453: The later-model 410's in the new silver-grey XE coloring. Only small numbers seem to have been produced, as by this time floppy disks were now almost universal in the US and most of Europe. The XE line was later sold primarily in eastern Europe, South America and other markets that had not previously seen low-cost home computers . These markets remained highly cost sensitive and the cassette recorder

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3432-412: The next year, with the last known reference being Atari's internal price list of 24 August 1981. To support the larger storage capacity, the drives used a modified version of DOS 2.0, 2.0D. The controller was custom and only supported MFM, making the 815 incompatible with disks used in the 810. Third parties exploring the capabilities of the 810 system soon demonstrated that the 19.2 kbps speed of

3498-431: The one in the 810. Atari's drives entered the market almost two years later than Apple, giving them time to take advantage of the rapid improvements taking place in the industry. Most notable was the entry of several other manufacturers to the drive market, including Alps Electric and Micro Peripherals Inc (MPI). Atari arranged a deal with MPI for their mechanisms and designed their own controller to drive it, combining

3564-438: The power switch, similar to the one used on the computer and most other peripherals in the line. The unit drew about 20W, so it was normally turned off when not in use. Two LED lamps were placed on the front, one indicated that power was on and the other blinked when the drive was being accessed. The back of the case had two SIO ports to allow daisy-chaining, a ring jack for the external power supply , and two pin switches to select

3630-504: The protocol used for the transmission of spacecraft instrument data over the deep-space channel. Under this standard, an image or other data sent from a spacecraft instrument is transmitted using one or more packets. Packetized elementary stream (PES) is a specification associated with the MPEG-2 standard that allows an elementary stream to be divided into packets. The elementary stream is packetized by encapsulating sequential data bytes from

3696-484: The same disks to store twice as much data, 180 kB. Early advertising for the new machines often showed the 815 , which combined two drives in a single case and used MFM encoding. The price was listed at $ 1,495. For reasons unknown, the 815 was never produced in quantity. Small numbers were hand-built using Tandon drives during 1980 and a few shipped to customers starting in June, but full-scale production never began. It continued to appear on company price lists for

3762-543: The socket for the FD1771 chip, providing more separation between the signals and improving read reliability. It also attempted to address the motor control speed issues, which required the Side Board to be replaced and the voltage of the circuit to be increased to 12V. As the original 9V power supply was retained, the conversion required more power to provide a second 12V output, increasing average use from about 20W to 30W. The upgrade

3828-548: The sounds as "At times it almost seemed sick, the groans and creaks were so intense." Brian Moriarty, writing in the ANALOG Computing magazine, described it as having "notoriously poor speed regulation" in maintaining its non-standard 288 RPM, while Garry Francis noted in Page 6 magazine that the speed would tend to drift over time, causing disks written at different speeds to become unreadable without adjustment. This led to

3894-437: The start of the header and data elements by their location relative to the start of the packet. Some protocols format the information at a bit level instead of a byte level. A packet may contain any of the following components: IP packets are composed of a header and payload. The header consists of fixed and optional fields. The payload appears immediately after the header. An IP packet has no trailer. However, an IP packet

3960-454: The starting location of where to place the data in memory, and the final two held the location to jump to, to start the program running. When the system was booted with the Start key held down, the computer would attempt a cassette boot. This would play a tone on the television speaker to indicate the computer was ready, at which point the user would press Play on the drive and then press any key on

4026-405: The two outputs would toggle DATAIN on and off, which was automatically interpreted by the POKEY and reformed into a series of bytes for storage. While most systems of the era wrote bytes of data with no particular overall format, Atari's driver used a simple packetized format to aid in error detection . Data was split into packets of 128 bytes and then sent to the tape with three header bytes and

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4092-408: Was designed by Roy Nishi and Russ Farnell. It used identical C-shaped sections for the top and bottom of the drive, with four small circular indentations embossed into the case where rubber feet were adhered on the bottom during assembly. This meant the feet on one drive were naturally positioned over the empty circles on the top of the drive below it, providing sturdy stacking. The front of the case had

4158-470: Was generally around 6 kbps, compared to about 15 kbps for the Disk II. This is one reason the machine was never considered seriously in the business market; applications like VisiCalc were not competitive with the Apple II when run on the Atari or Commodore 64 . In a 1982 review for a third party replacement, InfoWorld described the 810 as "noisy, slow and inefficient by today's standards, and it had some reliability problems" and then described

4224-671: Was intended to allow the computer to perform more complex processing of the data, allowing it to stop the transfer and thereby giving it any amount of time needed. Normal IRG was not widely used, the only known examples being assembly language programs be loaded in ATASCII format, and the much more rarely used ability to load and store BASIC programming language as text. When stored as text, each line had to be read in and then converted to tokenized format, which could take some time. Generally, BASIC programs were instead stored in their tokenized form which could be read and written as binary data using

4290-593: Was offered to owners of earlier models. In November 1981 a further upgrade was offered with the C-version ROM. This modified the sector layout during formatting to improve reading performance, as much as 20% on average. Like the DS, the C-version ROM was also offered to existing owners. From February 1982 the line switched to the "810M Analog" version. This added an entirely new card, the Power Supply Board, which included

4356-473: Was still a viable system. Most sets from this era are variations on the XC12, using a Phonemark PM-4401A mechanism, the same unit as the Commodore Datasette . This was sized between the 410 and 1010 and was sold in all of Atari's markets. Several versions of the XC12 were also produced for specific markets, differing primarily in labelling. In Poland, they could be found as the XCA12 or CA12. A later modification led to

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