Статті в журналах з теми "REVERSE CARRY PROPAGATE ADDER"

The design of a 32-bit carry-skip adder to achieve minimum delay is presented in this paper. A fast carry look-ahead logic using group generate and group propagate functions is used to speed up the performance of multiple stages of ripple carry adders. The group generate and group propagate functions are generated in parallel with the carry generation for each block. The optimum block sizes are decided by considering the critical path into account. The new architecture delivers the sum and carry outputs in lesser unit delays than existing carry-skip adders. The adder is implemented in 0.25 m CMOS technology at 3.3 V. The critical delay for the proposed adder is 3.4 nanoseconds. The simulation results show that the proposed adder is 18 faster than the current fastest carry-skip adder.

In processors and in digital circuit designs, adder is an important component. As a result, adder is the main area of research in VLSI system design for improving the performance of a digital system. The performance depends on power consumption and delay. Adders are not only used for arithmetic operations, but also for calculating addresses and indices. In digital design we have half adder and full adder, by using these adders we can implement ripple carry adder (RCA). RCA is used to perform any number of additions. In this RCA is serial adder and it has propagation delay problem. With increase in hard & fast circuits, delay also increases simultaneously. That’s the reason these Carry look ahead adders (CLA) are used. The carry look ahead adder speeds up the addition by reducing the amount of time required to determine carry bits. It uses two blocks, carry generator (Gi) and carry propagator (Pi) which finds the carry bit in advance for each bit position from the nearest LSB, if the carry is 1 then that position is going to propagate a carry to next adder.

Addition usually affects the overall performance of digital systems and an arithmetic function. Adders are most widely used in applications like multipliers, DSP (i.e., FFT, FIR, and IIR). In digital adders, the speed of addition is constrained by the time required to propagate a carry through the adder. Various techniques have been proposed to design fast adders. We have derived architectures for carry-select adder (CSA), Common Boolean Logic (CBL) based adders, ripple carry adder (RCA), and Carry Look-Ahead Adder (CLA) for 8-, 16-, 32-, and 64-bit length. In this work we have done comparative analysis of different types of adders in Synopsis Design Compiler using different standard cell libraries at 32/28 nm. Also, the designs are analyzed for the stuck at faults (s-a-0, s-a-1) using Synopsis TetraMAX.

This This paper addresses a novel technique in implementing hybrid parallel-prefix adder (HPA) incorporating prefix-tree structure with Carry Select Adder (CSEA). Ling’s algorithm is used to optimise the pre-processing blocks (white nodes) and intermediate Generate-Propagate blocks (Black nodes) of the prefix tree to minimise the congestion of wires which contributes to reduction in chip size and to improve performance. The resulting prefix-tree arrangement is then merged into a sequence of modified CSEA. Experimental results show that HPA has speed improvement of 62% and 13% power reduction in comparison of the traditional Carry Look-Ahead Adder (CLA).

Adder circuits play a remarkable role in modern microprocessor. Adders are widely used in critical paths of arithmetic operation such as multiplication and subtraction. A Carry Select Adder (CSA) design methodology using a modified 4-bit Carry Look-Ahead (CLA) Adder has been proposed in this research. The proposed 4-bit CLA used hybrid logic style based logic circuits for Carry Generate (Gi) and Carry Propagate (Pi) functions in order to improve performance and reduce the number of transistor used. The modified 4-bit CLA is used as the basic unit for implementation of 32-bit CSA. The proposed design of hybrid CLA based 32-bit CSA has been compared with conventional static CMOS based 32-bit CSA and 32-bit Ripple Cary Adder (RCA) by conducting simulation using Cadence Virtuoso. Power consumption and delay in the proposed 32-bit CSA found 322.6 (uW) and 0.556 (ns) whereas power and delay in the conventional 32-bit CSA was 455.4 (uW) and 0.667 (ns) respectively. We have done all the simulation using Cadence Virtuoso 90 nm tool.

Adders are of fundamental importance in a wide variety of digital systems. This paper presents a novel bit block structure which computes propagate signals as carry strength. Power consumption is one of the most significant parameters of carry select adder.The proposed method aims on GDI(Gate Diffusion Input) Technique. Modified GDI is a novel technique for low power digital circuits design further to reduce the swing degradation problem. This techniques allows reduction in power consumption, carry propagation delay and transistor count of the carry select adder.This technique can be used to reduce the number of transistors compared to conventional CSLA and made comparison with known conventional adders which gives that the usage of carry-strength signals allows high-speed adders to be realised at lower cost as well as consuming lower power than previous designs. Hence, this paper we are concentrating on the area level &we are reducing the power using modified GDI logic.

The efficiency of residue number system depends on the reverse converter due to several modulo operations like addition, subtraction and multiplication. In this paper, a design of new four moduli set [Formula: see text], reverse converter is presented. The moduli set have moduli with length ranging from ([Formula: see text]) to ([Formula: see text])-bits. The reverse conversion for moduli set [Formula: see text] has been optimized in existing state of art. Thus, proposed converter is based on two new moduli set [Formula: see text] and utilizes the mixed radix conversion. This converter is memoryless, and occupies least area. The proposed converter is based on carry save adder (CSA) and modulo adder enabling more speed and less hardware complexity for dynamic range of [Formula: see text]-bit, offering good area-delay product.

In this paper, an efficient implementation of a 16 bit array hierarchy multiplier using full swing Gate Diffusion Input (GDI) logic is discussed. Hierarchy multiplier is attractive because of its ability to carry the multiplication operation withi one clock cycle. The existing hierarchical multipliers occupy more area and suffer from accumulation delay of base multiplier output bits. These issues can be addressed by incorporating carry select adder based addition and the multiplier implementation using full swing GDI logic. The basic computation blocks involved in the multiplier are AND gate and carry propagate adder. They are implemented with using full swing GDI logic. Due to their reduced transistor count and less power consumption, this multiplier implementation leads to significant improvement compared with the existing implementations. The designed and existing array multipliers are simulated at 45 nm technology model and their power consumption and delay are calculated from the simulation results. It is validated that the proposed hierarchy array multiplier based on full swing GDI logic has 27% less energy consumption than the existing design. The results confirmed that implemented multiplier has shown better performance and can be used for signal and im age processing.

An area-efficient high Wallace tree multiplier using adders is presented in this paper. The proposed Wallace tree multiplier is designed using logic gates and adders. The design is implemented in Cadence Virtuoso using a 45-nm technology library. The proposed design offers reduced delay and higher performance than conventional multipliers using carry-save adders with majority-based gate adder logic. The design also offers a reduced transistor count of 12, which is minimal compared to that of the conventional design. One of the fundamental building blocks of many VLSI applications is multipliers. To enhance the performance of circuits and systems, the design of multipliers is very important. The key feature of a high-performance Wallace tree multiplier lies in its efficient reduction of partial product additions. By utilising a combination of carry-save and carry-propagate adders, it minimises the critical path delay and maximises the speed of multiplication. Additionally, advanced optimisation techniques such as parallel prefix adders and parallel carry-save adders can be employed to further improve performance.

Computing images in reverse time migration and model parameter gradients from adjoint wavefields in full-waveform inversion (FWI) requires the correlation of a forward-propagated wavefield with another reverse-propagated wavefield. Although in theory only two wavefield propagations are required, one forward propagation and one reverse propagation, it requires storing the forward-propagated wavefield as a function of time to carry out the correlations, which is associated with significant input/output (I/O) cost. Alternatively, three wavefield propagations can be carried out to reverse propagate the forward-propagated wavefield in tandem with the reverse-propagated wavefield. We have determined how highly accurate reverse time migrated images and FWI model parameter gradients for anisotropic elastic FWI can be efficiently computed without significant disk I/O using two wavefield propagations by means of the principle of superposition.

Purpose The high demand for fast, energy-efficient, compact computational blocks in digital electronics has led the researchers to use approximate computing in applications where inaccuracy of outputs is tolerable. The purpose of this paper is to present two ultra-high-speed current-mode approximate full adders (FA) by using carbon nanotube field-effect transistors. Design/methodology/approach Instead of using threshold detectors, which are common elements in current-mode logic, diodes are used to stabilize voltage. Zener diodes and ultra-low-power diodes are used within the first and second proposed designs, respectively. This innovation eliminates threshold detectors from critical path and makes it shorter. Then, the new adders are employed in the image processing application of Laplace filter, which detects edges in an image. Findings Simulation results demonstrate very high-speed operation for the first and second proposed designs, which are, respectively, 44.7 per cent and 21.6 per cent faster than the next high-speed adder cell. In addition, they make a reasonable compromise between power-delay product (PDP) and other important evaluating factors in the context of approximate computing. They have very few transistors and very low total error distance. In addition, they do not propagate error to higher bit positions by generating output carry correctly. According to the investigations, up to four inexact FA can be used in the Laplace filter computations without a significant image quality loss. The employment of the first and second proposed designs results in 42.4 per cent and 32.2 per cent PDP reduction compared to when no approximate FA are used in an 8-bit ripple adder. Originality/value Two new current-mode inexact FA are presented. They use diodes as voltage regulators to design current-mode approximate full-adders with very short critical path for the first time.

Among the extracellular vesicles, apoptotic bodies (ABs) are only formed during the apoptosis and perform a relevant role in the pathogenesis of different diseases. Recently, it has been demonstrated that ABs from human renal proximal tubular HK-2 cells, either induced by cisplatin or by UV light, can lead to further apoptotic death in naïve HK-2 cells. Thus, the aim of this work was to carry out a non-targeted metabolomic approach to study if the apoptotic stimulus (cisplatin or UV light) affects in a different way the metabolites involved in the propagation of apoptosis. Both ABs and their extracellular fluid were analyzed using a reverse-phase liquid chromatography-mass spectrometry setup. Principal components analysis showed a tight clustering of each experimental group and partial least square discriminant analysis was used to assess the metabolic differences existing between these groups. Considering the variable importance in the projection values, molecular features were selected and some of them could be identified either unequivocally or tentatively. The resulting pathways indicated that there are significant, stimulus-specific differences in metabolites abundancies that may propagate apoptosis to healthy proximal tubular cells; thus, we hypothesize that the share in apoptosis of these metabolites might vary depending on the apoptotic stimulus.

The hypothesis of estimated measure is to design computation quality for computation efforts. The Approximate full adders (AFA’s) are the lead objective to reduce the length of carry propagation which is put through to the slightest error rate. Approximate adder comes up with important enhancement in delay, area and power. The developing attribute is carry doesn't propagate in it. So in this we mainly use the hybrid adders where it utilizes the RCPFA. The approximate adder generates the input carry from higher bit to lower bit to produce carry output, , the weight of the carry reduces when it generates. In Reverse Carry Propagate Adder there are accomplishments to be completed those are the power, delay and energy. So, compared to the conventional ones the Approximate Mirror Adders (AMA's) has less transistors compared to it. This is to establish on the internal structure of the mirror adder which consumes less area and power consumption as well as higher speed. The representation performed by the RCPFA and hybrid adders is observed and compared using Mentor Graphics. As a result, it consists of higher accuracies and specifies that, by working on the RCPFA in the hybrid adders can consists of improved consumption of area by 14%, consumption of power by 19.2%, consumption of delay by 27%

In numerous processors math unit is fundamental structure square like DSPs and chip. Adders are key structure obstructs in ALUs. In this manner expanding adders speed, lessening their vitality utilization and zone firmly impact the speed, control utilization and region of processor. There are numerous takes a shot at the subject of advancing velocity, zone of these units. One of way to deal with improve both the territory and speed is to forfeit the calculation precision. This methodology is rough registering, might be utilized for the applications where a few blunders might be endured. In Reverse Carry Propagate Adder (RCPA) the convey engenders in a counter-take the path of least resistance way from MSB to LSB, subsequently the information convey sign has higher significance than the yield bring. This methodology of convey proliferation brings about better solidness inside the commonness of put off varieties. Three execution of the Reverse Carry Propagate Adder (RCPA) cell by various speed, power and precision degrees are presented. The proposed structure might be joined with a definite (forward) convey viper to frame cross breed adders with tunable degrees of exactness. Further this venture is upgraded by 16-piece Modified SQRT Carry Select snake. This upgrade improves the territory, time enhancement in snake usage..

The appropriate selection of moduli has a significant impact on the reverse converter's speed and complexity. The modified converter depends upon the arithmetic designs that are implemented without the read - only memories and lookup tables. The Carry Save Adder and Carry Propagate Adder are used in the reverse converter and modulo adder gives higher speed and less hardware complexity. The proposed converter has been implemented to get the conversion time and area as supported by the reverse converter of 12-bits and maximum up to 100-bits.

In this paper, two accuracy configurable adders capable of operating in approximate and exact modes are proposed. In the adders, which include a block-based carry propagate and a parallel prefix structure, the carry chains are cut off in the approximate mode limiting the carry chain depth to two blocks. In the case of parallel prefix adder, we propose a special carry generate tree equipped with a power gating means. In both of the proposed structures, the critical paths of the adders are not increased in the exact operating mode. Thus, the main objective of proposing these approximate adder structures is to present an accuracy configurable adder structure whose delay in the exact mode is almost the same as an exact adder. The efficacies of the proposed accuracy configurable adders are compared with some state-of-the-art adder structures using a 15nm CMOS technology. In addition, their efficacies are evaluated in two error-resilient applications. These studies show that the proposed carry-propagate adder has 22% (51%) lower energy consumption (error rate) compared to the best prior works. Also, the proposed parallel prefix adder provides, on average, 20% lower energy consumption compared to the exact parallel prefix adders.

The dominant portion of power dissipation in CMOS adder circuits, due to logic transitions, varies as the square of the supply, significant savings in power dissipation may be exacted by operating with reduced supply voltage. If the supply voltage is reduced while threshold voltage stays same, the noise margins will reduce. Addition is a crucial process because it usually involve carry ripple steps which must propagate a carry signal from each bit to it’s higher bit position. This results in a substantial circuit delay. The adder which lies in the crucial delay path will effectively determine the system overall speed. To improve noise margins, the threshold voltages must also be made smaller. However subthreshold leakage current increases exponentially when threshold voltage is reduced. The higher static dissipation may then offset the reduction in transitions portion of the dissipation. Hence the devices needed to have threshold voltages that maximizes the net reduction in the dissipation. Addition is an obligatory operation that is crucial to processing the fundamental arithmetic operations. Due to the potential versatility of adders in this contemporary research field, the existing adders and adder designs currently intended for future low voltage and low power environments. This can be achieved by the CMOS adders namely Parallel Adder, Ripple Carry Adder(RCA), Carry Look Ahead Adder(CLA), Carry Select Adder(CSL), Carry Save Adder(CSA), Carry Skip Adder(CSK), Conditional Sum Adder(COS).

As One Giga Hertz microprocessors power mobiles, laptops, tablets and personal computers in last few years, there is a massive need to reduce the number cycles to do addition which plays a significant role in Arithmetic Logic Unit (ALU) or Digital Signal Processing (DSP). The complexity of carry propagation is the critical variable once the designs requires addition over 32 bits. A hierarchical design has been developed to find Carry out at 16-bit stage from Propagate and Generate techniques from a 4-bit stage of Carry Lookahead Adder (CLA), so called Carry Lookahead Logic (CLL). Four blocks of CLL have been used to create another CLL block at a 16-bit level and similarly at 64 bit level and 128 bit level. A 65 nm CMOS technology library from Microwind used to simulate from logic to circuit level for the hierarchical design of 128 bit CLA and compared with 90 nm technology

The Residue Number System (RNS) based reverse converter can play as main role in Parallel arithmetic operations of Digital Signal Processing (DSP) applications and VLSI technologies. Normally, by the use of carry adders, the reverse conversion design gives high delay and high power consumption. Due to resolve of above problem, the design of reverse converter is proposed by the use of familiar high speed (less propagation delay) Parallel Prefix - Kogge Stone Adder (PP- KSA). This paper describes the design of 32-bit Reverse converter with regular PP-KSA and proposed MUX (Multiplex) logic of PP-KSA with Hybrid Modular Parallel Prefix structure (HMPE) separately. In addition to that, the performance of that designs are analysed based on area, delay and power independently. The Performance results of proposed MUX logic of PP-KSA Reverse converter design yields low power than the other design which uses the regular PP-KSA. The simulation and synthesis effects can be done in Xilinx ISE 14.2i tool.

This paper presents a one-level decomposition Haar Discrete Wavelet Transform (DWT) architecture using a 4:2 compressor and carry propagate adder. In Haar DWT architecture, coefficient multiplication is an essential operation. The Haar coefficient multiplication [Formula: see text] is implemented with [Formula: see text] multiplier and the generated partial products are represented with sign power of two (SPT) terms. The addition of SPT terms is computed with a 4:2 compressor and the final sum is computed with CPA. A [Formula: see text] multiplier with 4:2 compressor technique is used to improve energy and delay. Compared to the previous architectures, the proposed architecture gives reduction in area, power, and delay. The proposed Haar wavelet architecture is implemented in gate-level Verilog HDL and synthesized with UMC 90-nm technology using Cadence RC compiler. When compared to the existing designs, the proposed architecture Haar DWT architecture synthesis results show reduction in latency of 32.32% and 31.46% of circuit area.

This paper provides embedded, reflective practice-based insight arising from my experience collaborating to produce online and print-on-demand editions of a magazine showcasing the photography of members of haphazart! Contemporary Abstracts group (hereafter referred to as haphazart!). The group’s online visual, textual and activity-based practices via the photo sharing social networking site Flickr are portrayed as achieving cohesive visual identity. Stylistic analysis of pictures in support of this claim is not attempted. Rather negotiation, that Elliot has previously described in M/C Journal as innate in collaboration, is identified as the unifying factor. However, the collaborators’ adherence to Flickr’s communication platform proves problematic in the editorial context. Some technical incoherence with possible broader cultural implications is encountered during the process of repurposing images from screen to print. A Scan of Relevant Literature The photographic gaze perceives and captures objects which seem to ‘carry within them ready-made’ a work of art. But the reminiscences of the gaze are only made possible by knowing and associating with groups that define a tradition. The list of valorised subjects is not actually defined with reference to a culture, but rather by familiarity with a limited group. (Chamboredon 144) As part of the array of socio-cultural practices afforded by Web 2.0 interoperability, sites of produsage (Bruns) are foci for studies originating in many disciplines. Flickr provides a rich source of data that researchers interested in the interface between the technological and the social find useful to analyse. Access to the Flickr application programming interface enables quantitative researchers to observe a variety of means by which information is propagated, disseminated and shared. Some findings from this kind of research confirm the intuitive. For example, Negoecsu et al. find that “a large percentage of users engage in sharing with groups and that they do so significantly” ("Analyzing Flickr Groups" 425). They suggest that Flickr’s Groups feature appears to “naturally bring together two key aspects of social media: content and relations.” They also find evidence for what they call hyper-groups, which are “communities consisting of groups of Flickr groups” ("Flickr Hypergroups" 813). Two separate findings from another research team appear to contradict each other. On one hand, describing what they call “social cascades,” Cha et al. claim that “content in the form of ideas, products, and messages spreads across social networks like a virus” ("Characterising Social Cascades"). Yet in 2009 they claim that homocity and reciprocity ensure that “popularity of pictures is localised” ("Measurement-Driven Analysis"). Mislove et al. reflect that the affordances of Flickr influence the growth patterns they observe. There is optimism shared by some empiricists that through collation and analysis of Flickr tag data, the matching of perceptual structures of images and image annotation techniques will yield ontology-based taxonomy useful in automatic image annotation and ultimately, the Semantic Web endeavour (Kennedy et al.; Su et al.; Xu et al.). Qualitative researchers using ethnographic interview techniques also find Flickr a valuable resource. In concluding that the photo sharing hobby is for many a “serious leisure” activity, Cox et al. propose that “Flickr is not just a neutral information system but also value laden and has a role within a wider cultural order.” They also suggest that “there is genuinely greater scope for individual creativity, releasing the individual to explore their own identity in a way not possible with a camera club.” Davies claims that “online spaces provide an arena where collaboration over meanings can be transformative, impacting on how individuals locate themselves within local and global contexts” (550). She says that through shared ways of describing and commenting on images, Flickrites develop a common criticality in their endeavour to understand images, each other and their world (554).From a psychologist’s perspective, Suler observes that “interpersonal relationships rarely form and develop by images alone” ("Image, Word, Action" 559). He says that Flickr participants communicate in three dimensions: textual (which he calls “verbal”), visual, and via the interpersonal actions that the site affords, such as Favourites. This latter observation can surely be supplemented by including the various games that groups configure within the constraints of the discussion forums. These often include submissions to a theme and voting to select a winning image. Suler describes the place in Flickr where one finds identity as one’s “cyberpsychological niche” (556). However, many participants subscribe to multiple groups—45.6% of Flickrites who share images share them with more than 20 groups (Negoescu et al., "Analyzing Flickr Groups" 420). Is this a reflection of the existence of the hyper-groups they describe (2009) or, of the ranging that people do in search of a niche? It is also probable that some people explore more than a singular identity or visual style. Harrison and Bartell suggest that there are more interesting questions than why users create media products or what motivates them to do so: the more interesting questions center on understanding what users will choose to do ultimately with [Web2.0] capabilities [...] in what terms to define the success of their efforts, and what impact the opportunity for individual and collaborative expression will have on the evolution of communicative forms and character. (167) This paper addresseses such questions. It arises from a participatory observational context which differs from that of the research described above. It is intended that a different perspective about online group-based participation within the Flickr social networking matrix will avail. However, it will be seen that the themes cited in this introductory review prove pertinent. Context As a university teacher of a range of subjects in the digital media field, from contemporary photomedia to social media to collaborative multimedia practice, it is entirely appropriate that I embed myself in projects that engage, challenge and provide me with relevant first-hand experience. As an academic I also undertake and publish research. As a practicing new media artist I exhibit publically on a regular basis and consider myself semi-professional with respect to this activity. While there are common elements to both approaches to research, this paper is written more from the point of view of ‘reflective practice’ (Holmes, "Reconciling Experimentum") rather than ‘embedded ethnography’ (Pink). It is necessarily and unapologetically reflexive. Abstract Photography Hyper-Group A search of all Flickr groups using the query “abstract” is currently likely to return around 14,700 results. However, only in around thirty of them does the group name, its stated rules and, the stream of images that flow through the pool arguably reflect a sense of collective concept and aesthetic that is coherently abstract. This loose complex of groups comprises a hyper-group. Members of these groups often have co-memberships, reciprocal contacts, and regularly post images to a range of groups and comment on others’ posts to be found throughout. Given that one of Flickr’s largest groups, Black and White, currently has around 131,150 members and hosts 2,093,241 items in its pool, these abstract special interest groups are relatively small. The largest, Abstract Photos, has 11,338 members and hosts 89,306 items in its pool. The group that is the focus of this paper, haphazart!, currently has 2,536 members who have submitted 53,309 items. The group pool is more like a constantly flowing river because the most recently added images are foremost. Older images become buried in an archive of pages which cannot be reverse accessed at a rate greater than the seven pages linked from a current view. A member’s presence is most immediate through images posted to a pool. This structural feature of Flickr promotes a desire for currency; a need to post regularly to maintain presence. Negotiating Coherence to the Abstract The self-managing social dynamics in groups has, as Suler proposes to be the case for individuals, three dimensions: visual, textual and action. A group integrates the diverse elements, relationships and values which cumulatively constitute its identity with contributions from members in these dimensions. First impressions of that identity are usually derived from the group home page which consists of principal features: the group name, a selection of twelve most recent posts to the pool, some kind of description, a selection of six of the most recent discussion topics, and a list of rules (if any). In some of these groups, what is considered to constitute an abstract photographic image is described on the group home page. In some it is left to be contested and becomes the topic of ongoing forum debates. In others the specific issue is not discussed—the images are left to speak for themselves. Administrators of some groups require that images are vetted for acceptance. In haphazart! particular administrators dutifully delete from the pool on a regular basis any images that they deem not to comply with the group ethic. Whether reasons are given or not is left to the individual prosecutor. Mostly offending images just disappear from the group pool without trace. These are some of the ways that the coherence of a group’s visual identity is established and maintained. Two groups out of the abstract photography hyper-group are noteworthy in that their discussion forums are particularly active. A discussion is just the start of a new thread and may have any number of posts under it. At time of writing Abstract Photos has 195 discussions and haphazart! — the most talkative by this measure—has 333. Haphazart! invites submissions of images to regularly changing themes. There is always lively and idiosyncratic banter in the forum over the selection of a theme. To be submitted an image needs to be identified by a specific theme tag as announced on the group home page. The tag can be added by the photographer themselves or by anyone else who deems the image appropriate to the theme. An exhibition process ensues. Participant curators search all Flickr items according to the theme tag and select from the outcome images they deem to most appropriately and abstractly address the theme. Copies of the images together with comments by the curators are posted to a dedicated discussion board. Other members may also provide responses. This activity forms an ongoing record that may serve as a public indicator of the aesthetic that underlies the group’s identity. In Abstract Photos there is an ongoing discussion forum where one can submit an image and request that the moderators rule as to whether or not the image is ‘abstract’. The same group has ongoing discussions labelled “Hall of Appropriate” where worthy images are reposted and celebrated and, “Hall of Inappropriate” where images posted to the group pool have been removed and relegated because abstraction has been “so far stretched from its definition that it now resides in a parallel universe” (Askin). Reasons are mostly courteously provided. In haphazart! a relatively small core of around twelve group members regularly contribute to the group discussion board. A curious aspect of this communication is that even though participants present visually with a ‘buddy icon’ and most with a screen name not their real name, it is usual practice to address each other in discussions by their real Christian names, even when this is not evident in a member’s profile. This seems to indicate a common desire for authenticity. The makeup of the core varies from time to time depending on other activities in a member’s life. Although one or two may be professionally or semi-professionally engaged as photographers or artists or academics, most of these people would likely consider themselves to be “serious amateurs” (Cox). They are internationally dispersed with bias to the US, UK, Europe and Australia. English is the common language though not the natural tongue of some. The age range is approximately 35 to 65 and the gender mix 50/50. The group is three years old. Where Do We Go to from Here? In early January 2009 the haphazart! core was sparked into a frenzy of discussion by a post from a member headed “Where do we go to from here?” A proposal was mooted to produce a ‘book’ featuring images and texts representative of the group. Within three days a new public group with invited membership dedicated to the idea had been established. A smaller working party then retreated to a private Flickr group. Four months later Issue One of haphazart! magazine was available in print-on-demand and online formats. Following however is a brief critically reflective review of some of the collaborative curatorial, editorial and production processes for Issue Two which commenced in early June 2009. Most of the team had also been involved with Issue One. I was the only newcomer and replaced the person who had undertaken the design for Issue One. I was not provided access to the prior private editorial ruminations but apparently the collaborative curatorial and editorial decision-making practices the group had previously established persisted, and these took place entirely within the discussion forums of a new dedicated private Flickr group. Over a five-month period there were 1066 posts in 54 discussions concerning matters such as: change of format from the previous; selection of themes, artists and images; conduct of and editing of interviews; authoring of texts; copyright and reproduction. The idiom of those communications can be described as: discursive, sporadic, idiosyncratic, resourceful, collegial, cooperative, emphatic, earnest and purposeful. The selection process could not be said to follow anything close to a shared manifesto, or articulation of style. It was established that there would be two primary themes: the square format and contributors’ use of colour. Selection progressed by way of visual presentation and counter presentation until some kind of consensus was reached often involving informal votes of preference. Stretching the Limits of the Flickr Social Tools The magazine editorial collaborators continue to use the facilities with which they are familiar from regular Flickr group participation. However, the strict vertically linear format of the Flickr discussion format is particularly unsuited to lengthy, complex, asynchronous, multithreaded discussion. For this purpose it causes unnecessary strain, fatigue and confusion. Where images are included, the forums have set and maximum display sizes and are not flexibly configured into matrixes. Images cannot readily be communally changed or moved about like texts in a wiki. Likewise, the Flickrmail facility is of limited use for specialist editorial processes. Attachments cannot be added. This opinion expressed by a collaborator in the initial, open discussion for Issue One prevailed among Issue Two participants: do we want the members to go to another site to observe what is going on with the magazine? if that’s ok, then using google groups or something like that might make sense; if we want others to observe (and learn from) the process - we may want to do it here [in Flickr]. (Valentine) The opinion appears socially constructive; but because the final editorial process and production processes took place in a separate private forum, ultimately the suggested learning between one issue and the next did not take place. During Issue Two development the reluctance to try other online collaboration tools for the selection processes requiring visual comparative evaluation of images and trials of sequencing adhered. A number of ingenious methods of working within Flickr were devised and deployed and, in my opinion, proved frustratingly impractical and inefficient. The digital layout, design, collation and formatting of images and texts, all took place on my personal computer using professional software tools. Difficulties arose in progressively sharing this work for the purposes of review, appraisal and proofing. Eventually I ignored protests and insisted the team review demonstrations I had converted for sharing in Google Documents. But, with only one exception, I could not tempt collaborators to try commenting or editing in that environment. For example, instead of moving the sequence of images dynamically themselves, or even typing suggestions directly into Google Documents, they would post responses in Flickr. To Share and to Hold From the first imaginings of Issue One the need to have as an outcome something in one’s hands was expressed and this objective is apparently shared by all in the haphazart! core as an ongoing imperative. Various printing options have been nominated, discussed and evaluated. In the end one print-on-demand provider was selected on the basis of recommendation. The ethos of haphazart! is clearly not profit-making and conflicts with that of the printing organisation. Presumably to maintain an incentive to purchase the print copy online preview is restricted to the first 15 pages. To satisfy the co-requisite to make available the full 120 pages for free online viewing a second host that specialises in online presentation of publications is also utilised. In this way haphazart! members satisfy their common desires for sharing selected visual content and ideas with an online special interest audience and, for a physical object of art to relish—with all the connotations of preciousness, fetish, talisman, trophy, and bookish notions of haptic pleasure and visual treasure. The irony of publishing a frozen chunk of the ever-flowing Flickriver, whose temporally changing nature is arguably one of its most interesting qualities, is not a consideration. Most of them profess to be simply satisfying their own desire for self expression and would eschew any critical judgement as to whether this anarchic and discursive mode of operation results in a coherent statement about contemporary photographic abstraction. However there remains a distinct possibility that a number of core haphazart!ists aspire to transcend: popular taste; the discernment encouraged in camera clubs; and, the rhetoric of those involved professionally (Bourdieu et al.); and seek to engage with the “awareness of illegitimacy and the difficulties implied by the constitution of photography as an artistic medium” (Chamboredon 130). Incoherence: A Technical Note My personal experience of photography ranges from the filmic to the digital (Holmes, "Bridging Adelaide"). For a number of years I specialised in facsimile graphic reproduction of artwork. In those days I became aware that films were ‘blind’ to the psychophysical affect of some few particular paint pigments. They just could not be reproduced. Even so, as I handled the dozens of images contributed to haphazart!2, converting them from the pixellated place where Flickr exists to the resolution and gamut of the ink based colour space of books, I was surprised at the number of hue values that exist in the former that do not translate into the latter. In some cases the affect is subtle so that judicious tweaking of colour levels or local colour adjustment will satisfy discerning comparison between the screenic original and the ‘soft proof’ that simulates the printed outcome. In other cases a conversion simply does not compute. I am moved to contemplate, along with Harrison and Bartell (op. cit.) just how much of the experience of media in the shared digital space is incomparably new? Acknowledgement Acting on the advice of researchers experienced in cyberethnography (Bruckman; Suler, "Ethics") I have obtained the consent of co-collaborators to comment freely on proceedings that took place in a private forum. 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