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Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disk drives. LBA is a particularly simple linear addressing scheme; blocks are located by an integer index, with the first block being LBA 0, the second LBA 1, and so on.

The IDE standard included 22-bit LBA as an option, which was further extended to 28-bit with the release of ATA-1 (1994) and to 48-bit with the release of ATA-6 (2003), whereas the size of entries in on-disk and in-memory data structures holding the address is typically 32 or 64 bits. Most hard disk drives released after 1996 implement logical block addressing.

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Overview[edit]

In logical block addressing, only one number is used to address data, and each linear base address describes a single block.

The LBA scheme replaces earlier schemes which exposed the physical details of the storage device to the software of the operating system. Chief among these was the cylinder-head-sector (CHS) scheme, where blocks were addressed by means of a tuple which defined the cylinder, head, and sector at which they appeared on the hard disk. CHS did not map well to devices other than hard disks (such as tapes and networked storage), and was generally not used for them. CHS was used in early MFM and RLL drives, and both it and its successor, extended cylinder-head-sector (ECHS), were used in the first ATA drives. However, current disk drives use zone bit recording, where the number of sectors per track depends on the track number. Even though the disk drive will report some CHS values as sectors per track (SPT) and heads per cylinder (HPC), they have little to do with the disk drive's true geometry.

LBA was first introduced in SCSI as an abstraction. While the drive controller still addresses data blocks by their CHS address, this information is generally not used by the SCSI device driver, the OS, filesystem code, or any applications (such as databases) that access the 'raw' disk. System calls requiring block-level I/O pass LBA definitions to the storage device driver; for simple cases (where one volume maps to one physical drive), this LBA is then passed directly to the drive controller.

In redundant array of independent disks (RAID) devices and storage area networks (SANs) and where logical drives (logical unit numbers, LUNs) are composed via LUN virtualization and aggregation, LBA addressing of individual disk should be translated by a software layer to provide uniform LBA addressing for the entire storage device.

Enhanced BIOS[edit]

The earlier IDE standard from Western Digital introduced 22-bit LBA; in 1994, the ATA-1 standard allowed for 28 bit addresses in both LBA and CHS modes. The CHS scheme used 16 bits for cylinder, 4 bits for head and 8 bits for sector, counting sectors from 1 to 255. This means the reported number of heads never exceeds 16 (0–15), the number of sectors can be 255 (1–255; though 63 is often the largest used) and the number of cylinders can be as large as 65,536 (0–65535), limiting disk size to 128 GiB (≈137.4 GB), assuming 512 byte sectors. These values can be accessed by issuing the ATA command 'Identify Device' (ECh) to the drive.^[1]:87

However, the IBM BIOS implementation defined in the INT 13h disk access routines used quite a different 24-bit scheme for CHS addressing, with 10 bits for cylinder, 8 bits for head, and 6 bits for sector, or 1024 cylinders, 256 heads, and 63 sectors.^[2] This INT 13h implementation had pre-dated the ATA standard, as it was introduced when the IBM PC had only floppy disk storage, and when hard disk drives were introduced on the IBM PC/XT, INT 13h interface could not be practically redesigned due to backward compatibility issues. Overlapping ATA CHS mapping with BIOS CHS mapping produced the lowest common denominator of 10:4:6 bits, or 1024 cylinders, 16 heads, and 63 sectors, which gave the practical limit of 1024×16×63 sectors and 528MB (504 MiB), assuming 512 byte sectors.

In order for the BIOS to overcome this limit and successfully work with larger hard drives, a CHS translation scheme had to be implemented in the BIOS disk I/O routines which would convert between 24-bit CHS used by INT 13h and 28-bit CHS numbering used by ATA. The translation scheme was called large or bit shift translation. This method would remap 16:4:8 bit ATA cylinders and heads to 10:8:6 bit scheme used by INT 13h, generating much more 'virtual' drive heads than the physical disk reported. This increased the practical limit to 1024×256×63 sectors, or 8.4GB (7.8 GiB).

To further overcome this limit, INT 13h Extensions were introduced with the BIOS Enhanced Disk Drive Services, which removed practical limits on disk size for operating systems which are aware of this new interface, such as the DOS 7.0 component in Windows 95. This enhanced BIOS subsystem supports LBA addressing with LBA or LBA-assisted method, which uses native 28-bit LBA for addressing ATA disks and performs CHS conversion as needed.

The normal or none method reverts to the earlier 10:4:6 bit CHS mode which does not support addressing more than 528MB.

Until the release of ATA-2 standard in 1996, there were a handful of large hard drives which did not support LBA addressing, so only large or normal methods could be used. However, using the large method also introduced portability problems, as different BIOSes often used different and incompatible translation methods, and hard drives partitioned on a computer with a BIOS from a particular vendor often could not be read on a computer with a different make of BIOS. The solution was to use conversion software such as OnTrack Disk Manager, Micro House EZ-Drive/EZ-BIOS, etc., which installed to the disk's OS loader and replaced INT 13h routines at boot time with custom code. This software could also enable LBA and INT 13h Extensions support for older computers with non LBA-compliant BIOSes.

LBA-assisted translation[edit]

When the BIOS is configured to use a disk in LBA-assisted translation mode, the BIOS accesses the hardware using LBA mode, but also presents a translated CHS geometry via the INT 13h interface. The number of cylinders, heads, and sectors in the translated geometry depends on the total size of the disk, as shown in the following table.^[3]

LBA48[edit]

The current 48-bit LBA scheme was introduced in 2003 with the ATA-6 standard,^[4] raising the addressing limit to 2⁴⁸× 512 bytes, which is exactly 128PiB or approximately 144PB. Current PC-compatible computers support INT 13h Extensions, which use 64-bit structures for LBA addressing and should encompass any future extension of LBA addressing, though modern operating systems implement direct disk access and do not use the BIOS subsystems, except at boot load time. However, the common DOS style Master Boot Record (MBR) partition table only supports disk partitions up to 2TiB in size. For larger partitions this needs to be replaced by another scheme, for instance the GUID Partition Table (GPT) which has the same 64-bit limit as the current INT 13h Extensions.

CHS conversion[edit]

In the LBA addressing scheme, sectors are numbered as integer indexes; when mapped to CHS (cylinder-head-sector) tuples, LBA numbering starts with the first cylinder, first head, and track's first sector. Once the track is exhausted, numbering continues to the second head, while staying inside the first cylinder. Once all heads inside the first cylinder are exhausted, numbering continues from the second cylinder, etc. Thus, the lower the LBA value is, the closer the physical sector is to the hard drive's first (that is, outermost^[5]) cylinder.

CHS tuples can be mapped to LBA address with the following formula:^[6][7]

LBA = (C × HPC + H) × SPT + (S − 1)

where

• C, H and S are the cylinder number, the head number, and the sector number
• LBA is the logical block address
• HPC is the maximum number of heads per cylinder (reported by disk drive, typically 16 for 28-bit LBA)
• SPT is the maximum number of sectors per track (reported by disk drive, typically 63 for 28-bit LBA)

LBA addresses can be mapped to CHS tuples with the following formula ('mod' is the modulo operation, i.e. the remainder, and '÷' is integer division, i.e. the quotient of the division where any fractional part is discarded):

C = LBA ÷ (HPC × SPT)

H = (LBA ÷ SPT) mod HPC

S = (LBA mod SPT) + 1

According to the ATA specifications, 'If the content of words (61:60) is greater than or equal to 16,514,064, then the content of word 1 [the number of logical cylinders] shall be equal to 16,383.'^[1]:20 Therefore, for LBA 16450559, an ATA drive may actually respond with the CHS tuple (16319, 15, 63), and the number of cylinders in this scheme must be much larger than 1024 allowed by INT 13h.^[a]

Operating system dependencies[edit]

Operating systems that are sensitive to BIOS-reported drive geometry include Solaris, DOS and Windows NT family, where NTLDR (NT, 2000, XP, Server 2003) or WINLOAD (Vista, Server 2008, Windows 7 and Server 2008 R2) use Master boot record which addresses the disk using CHS; x86-64 and Itanium versions of Windows can partition the drive with GUID Partition Table which uses LBA addressing.

Some operating systems do not require any translation because they do not use geometry reported by BIOS in their boot loaders. Among these operating systems are BSD, Linux, macOS, OS/2 and ReactOS.

See also[edit]

• Cylinder-head-sector (CHS)

Notes[edit]

1. ^Though CHS addressing definitely uses the mathematical concept of tuple, it may also be considered an example of the general scheme called mixed radix by viewing its cylinders, heads and sectors as having different numerical bases; e.g., cylinders counting from 0 to 1023, heads from 0 to 254 and sectors from 1 to 63.

References[edit]

1. ^ ^ab'Information Technology - AT Attachment with Packet Interface - 5 (ATA/ATAPI-5)'(PDF). www.t13.org. 29 February 2000. Archived from the original(PDF) on 6 August 2020. Retrieved 15 December 2020.
2. ^'KB224526: Windows NT 4.0 supports maximum of 7.8-GB system partition'. Support.microsoft.com. 2007-02-23. Retrieved 2013-07-30.
3. ^Steunebrink, Jan. 'The BIOS IDE Harddisk Limitations'. Archived from the original on 6 October 2013. Retrieved 6 October 2013.
4. ^'Information Technology - AT Attachment with Packet Interface - 6 (ATA/ATAPI-6)'(PDF). www.t13.org. 26 February 2002. Archived from the original(PDF) on 6 August 2020. Retrieved 15 December 2020.
5. ^'Hard Disk Drive Basics'. active-undelete.com. Retrieved 2015-02-10. Track numbers start at 0, and track 0 is the outermost track of the disk. The highest numbered track is next to the spindle.
6. ^'Large Disk HOWTO, Section 3. Disk Access'. tldp.org. 2004-11-08. Retrieved 2015-02-10.
7. ^'The CHS to LBA Conversion Formulas'. pcrepairclass.tripod.com. Retrieved 2014-08-26.

External links[edit]

• Upgrading and Repairing PC's, by Scott Mueller. Pages 524–531.

Little Big Adventure is an action-adventure game developed by Adeline Software International and first released at the end of 1994. It was published in Europe by Electronic Arts and in North America, Asia and Oceania under the name Relentless: Twinsen's Adventure by Activision. Over 500,000 copies were sold by 1999. The game was initially released on CD-ROM and some time later on floppy disks; the CD-ROM version features full motion video, music and speech whereas the floppy disk version has MIDI music files and still images to replace the videos. The game was later ported to the PC-98 and FM Towns and was released in Japan in 1995. It was released for the PlayStation in Japan and Europe in 1996 and 1997 respectively, and to Android and iOS devices in 2014.^[1]

In 1997, a PC-only sequel was released under the name of Little Big Adventure 2 (also known as Twinsen's Odyssey).

On October 20, 2015, an 'Enhanced Edition' developed by DotEmu was released on Steam, alongside a re-release of the original game.^[2]

Gameplay[edit]

Little Big Adventure is a real-time pseudo-3D isometricaction-adventure game. All characters and vehicles in the game, including some props in the world, are real 3D polygon-based objects, performing actions within 2D pre-rendered environments. After completion of certain tasks the player is presented with a full motion video cut-scene. The player-character, Twinsen, can be switched between four different 'behaviour modes' (Normal, Athletic/Sporty, Aggressive, and Discreet), each changing the character's abilities and interactions with the game world.^[3] Combat in the game is mainly conducted using the Magic Ball, a glowing ball of energy which the player throws towards enemies, the trajectory and angle of the ball changing depending on the mode the player is in. Switching to the 'Aggressive' mode also allows Twinsen to engage in combat via punching and kicking.

The gameplay is partially free-roaming, allowing the player free non-linear travel around the islands of the game's world once they have been unlocked by completing certain objectives or solving certain puzzles; there are also many tasks which are optional or non-linear. Certain locations in the game are initially blocked from the player until they progress to a certain stage, such as the islands in the Northern Hemisphere and fortresses on several of the islands in the Southern Hemisphere.

The game features an autosave mechanic, which was a departure from the usual manual save system seen in most games of that time.^[4]

Lba 2 Mac Games Downloads

Plot[edit]

The game is set on the fictional planet Twinsun, a world which is held in a suspended orbit between two suns resulting in a polar region around its equator. Four different sentient species populate Twinsun; Quetchs are aesthetically similar to humans except that they all possess ponytails, Spheros are short spherical creatures, Grobos resemble anthropomorphic elephants, and Rabbibunnies are tall, thin humanoid rabbits. As the game begins, it is explained that all peoples of Twinsun have been herded into the Southern hemisphere by a brutal tyrant called Dr FunFrock, who has subjugated the planet by developing an army of clones which travel using teleport machines which he has dispersed around the planet. The player character is a young Quetch named Twinsen, who has been incarcerated in an asylum on the fortress-like Citadel Island because of his prophetic dreams about the end of the world.^[5]

Twinsen escapes from the asylum and returns to his house which he shares with his girlfriend Zoe. When Dr FunFrock's clones arrive to re-arrest him, Zoe hides Twinsen from them and is arrested herself. As Twinsen travels between the islands of the planet, seeking to find a way of overcoming FunFrock's clone army and recovering Zoe, he discovers that his strange dreams are in fact part of the Prophecy, a legendary tale regarding a being known as Sendell who is said to inhabit the core of the planet and watch over the people of Twinsun. Twinsen's dreams are in fact telepathic messages sent by Sendell, who chose his ancestors to help her watch over the planet centuries prior and is now contacting Twinsen (as the current descendant of his family line) to warn the inhabitants of the planet of the danger posed by FunFrock.

Realising that finding FunFrock and fulfilling the Prophecy is the only way to recover Zoe, Twinsen teams up with a group of rebels resisting the rule of FunFrock. The rebels help him sabotage FunFrock's cloning and teleportation abilities and give him passage through to the Northern Hemisphere, where FunFrock has set up a massive drilling operation into the heart of the planet. Twinsen breaks into FunFrock's main fortress and finds Zoe seemingly locked in a jail, but she is revealed to be a clone created by FunFrock as bait, and FunFrock reveals that with Twinsen safely locked up where he cannot fulfil his part of the Prophecy, he is free to drill through to the Well of Sendell, deep in the planet's core, where he hopes to encounter Sendell and gain the godly powers she possesses for himself.

Twinsen escapes from the clutches of FunFrock's clones and succeeds in blowing the fortress up, clearing the way for him to fight through FunFrock's drilling operation to reach the Well of Sendell. FunFrock waits with Zoe at the entrance to the Well, telling Twinsen that he'll spare Twinsen and Zoe if he opens the Well for FunFrock to advance and reach Sendell. Twinsen pushes FunFrock off the side of a cliff during a sword fight and opens the Well in order to complete the Prophecy, inadvertently allowing a surviving FunFrock access as well. Twinsen defeats FunFrock in a final confrontation, and him and Zoe encounter Sendell, a being appearing to consist purely of glowing electrical energy, who thanks them for saving a gestalt entity which she is protecting in the core of the planet. Sendell uses her powers to allow Twinsen and Zoe to fly back to the surface, where the inhabitants of the planet have prepared a celebration in Twinsen's honour.

Characters[edit]

Twinsen is the hero of the game. The chosen one of the planet, heir to its prophecy, he must gather magical objects and sabotage FunFrock's reign. He is voiced by Sylvain Caruso in French, and Dana Westberg in English.

Zoe is Twinsen's girlfriend. She is captured by two Grobo clones shortly after Twinsen escapes from the asylum. Near the end of the game, Twinsen rescues what he thinks is Zoe, but turns out to be a clone. Twinsen rescues the real Zoe at the very end of the game. She is voiced by Julie Bataille in French, and Trish Kessler-Caffrey in English.

Jerome Baldino (better known as Baldino) is the local inventor on Proxima Island. He aids Twinsen in the game with his protopack, which the player must use to rob a museum. He only appears for a short time, though he plays a bigger part in Little Big Adventure 2. He is voiced by Sylvain Caruso in French, and Christian Erickson in English.

FunFrock is the main antagonist of the game. He is the dictator of Twinsun who controls the planet using three powers: cloning, teleportation and mutant breeding. His true goal is to achieve the God-like status by destroying Sendell, the goddess of the planet. After Twinsen defeats him, the planet is peaceful again, and no longer under the reign of terror. It is revealed in Little Big Adventure 2 that Twinsen actually killed a clone of Funfrock in the end of the game. He is voiced by Pierre-Alain de Garrigues in French, and Christian Erickson in English.

Dino-Fly is a dinosaur with wings, roosting on top of Tippet Island. He says he has been waiting for the heir (who is Twinsen) for centuries. He helps Twinsen get to the other islands of the northern hemisphere of Twinsun. He is voiced by Pierre-Alain de Garrigues in French, and Christian Erickson in English.

Sendell is the goddess of Twinsun. She calls Twinsen for help in his dreams, warning him of FunFrock's dictatorship. She and other Sendells are watching over a Stellar Entity that is in gestation in the centre of Twinsun. She is seen briefly in the ending cutscene. She is voiced by Julie Bataille in French, and Trish Kessler-Caffrey in English.

Development[edit]

Frédérick Raynal, ex-Infogrames designer/lead programmer had grew disillusioned with Infogrames reluctance to listen to new ideas and concepts while working on the Alone in the Dark series, so founded his own development house where he was able to use these new ideas and concepts to create their debut game Little Big Adventure.^[4]

In an interview with Edge (magazine), lead coder Serge Plagnol stated that Electronic Arts US division repeatedly requested that Twinsen was changed into a 'much tougher character' and for him to 'kick ass'. Adeline Software International refused because the changes wouldn't have suited the game's story.^[4]

The music for the game was composed by Philippe Vachey^[6] who also composed music for Little Big Adventure 2.

In 1995, Atari Corporation realized a deal with EA to bring titles from their catalog to the Atari Jaguar CD, with Little Big Adventure among them but it was never released due to the commercial and critical failure of the Atari Jaguar platform.^[7][8][9]

In August 2011, co-founder of Adeline Software Didier Chanfray said in an interview that downloadable re-releases of both Little Big Adventure and its sequel were 'under negotiation'. He also added that a 'remix' of the game was being considered for release on touch-pad devices.^[10]

On 11 October 2011, the game was re-released for download by GOG.com, where it is available for both the Windows (XP, Vista, 7) and Mac OS X (10.6.8 or newer) platform.^[11]

In December 2011, discussion of a LBA1 remake was revealed in an interview with Frédérick Raynal, Sébastien Viannay, Didier Chanfray posted on GOG.com.^[12]

Lba 2 Mac Games Free

On 26 March 2014 and 27 March 2014 respectively, an Android^[13] and iOS^[14] version of Little Big Adventure were released.

Reception[edit]

Little Big Adventure was a commercial hit, with sales of 320,000 units by February 1997.^[17] By August 1999, its global sales had surpassed 500,000 units.^[18] However, the game was commercially unsuccessful in the United States, where it sold 30,000 units. Writer Daniel Ichbiah blamed this on Electronic Arts' 'incoherent marketing' of the game, and Frédérick Raynal criticized the publisher's decision to give Little Big Adventure a more aggressive name and cover artwork, and to portray combat in its advertisements.^[19]

Lba 2 Mac Games Download

Little Big Adventure was named the 38th best computer game ever by PC Gamer UK in 1997. The editors called it 'endearingly entertaining'.^[20]

Lba 2 Mac Games Offline

Next Generation reviewed the PC version of the game, rating it four stars out of five, and stated that 'Although puzzle content is light, there's still enough of a challenge here to keep most players happy from start to finish.'^[15]

References[edit]

1. ^'Nineties PC Adventure Game Little Big Adventure Gets an Android Port'. AndroidShock. 27 March 2014. Archived from the original on 2014-04-08. Retrieved 7 April 2014.
2. ^'LBA on Steam'. Store.steampowered.com. Archived from the original on 2018-07-28. Retrieved 28 July 2018.
3. ^House, Michael. 'Review - Relentless: Twinsen's Adventure'. allgame. Archived from the original on 2014-11-14. Retrieved 18 December 2009.
4. ^ ^abc'An audience with Adeline'. Edge. No. 31. April 1996. pp. 22–23. Retrieved 2020-03-31.
5. ^Fulljames, Stephen (15 August 2001). 'Little Big Adventure Review - Joyously engineered adventure'. Computer and Video Games. Archived from the original on 2007-07-10. Retrieved 18 December 2009.
6. ^'Interview with Philippe Vachey (in French)'. Archived from the original on 2007-11-10.
7. ^'CVG News - Atari's Cat Gets The CD Cream - Big Cat Claws EA Deal'. Computer and Video Games. No. 163. Future Publishing. June 1995. pp. 12–13. Archived from the original on 2018-10-18. Retrieved 2019-01-05.
8. ^Wallett, Adrian (September 23, 2017). 'Darryl Still (Atari/Kiss Ltd) – Interview'. arcadeattack.co.uk. Archived from the original on 2018-09-28. Retrieved 2018-09-28.
9. ^CRV (August 6, 2017). 'Blog:Legal Brief: Atari vs. Sega'. gdri.smspower.org. Archived from the original on 2018-11-16. Retrieved 2019-03-28.
10. ^'Gaming articles on Engadget'. Engadget. Archived from the original on 2015-02-28. Retrieved 28 July 2018.
11. ^'Little Big Adventure (Relentless: Twinsen's Adventure)'. GOG.com. Archived from the original on 2012-11-05. Retrieved 28 July 2018.
12. ^'Your questions about Little Big Adventure answered'. GOG.com. Archived from the original on 2012-04-28. Retrieved 28 July 2018.
13. ^'Little Big Adventure - Apps on Google Play'. Play.google.com. Archived from the original on 2018-07-13. Retrieved 28 July 2018.
14. ^'Little Big Adventure - Relentless: Twinsen's Adventure on the App Store'. App Store. Archived from the original on 2018-07-28. Retrieved 28 July 2018.
15. ^ ^ab'Finals'. Next Generation. No. 1. Imagine Media. January 1995. p. 97.
16. ^'Relentless: Twinsen's Adventure'. Secret Service Magazine (in Polish). 22: 66–67. February 1995.
17. ^Fontaine, Gilles (February 5, 1997). 'Jeux vidéo : une industrie lourde est née'. L'Express. Archived from the original on March 3, 2016.
18. ^'Jeux; Little Big Adventure'. No Cliché. Archived from the original on 1999-08-31. Retrieved 2019-01-05.
19. ^Ichbiah, Daniel (1997). La saga des jeux vidéo. Pocket. p. 191. ISBN2-266-08763-0.
20. ^Flynn, James; Owen, Steve; Pierce, Matthew; Davis, Jonathan; Longhurst, Richard (July 1997). 'The PC Gamer Top 100'. PC Gamer UK (45): 51–83.

External links[edit]

• Little Big Adventure at MobyGames
• LBA series at Curlie