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& 现在珍惜的光绪元宝银币价格是屡屡破新高，就在今年年初已经达到上千万元。今天就和大家一起来看看为什么光绪元宝银币能取得这么好的拍卖成绩。
& &光绪元宝为清代货币，光绪年间铸行金、银币较多。当时正值洋务运动时期，这股思潮也影响到了铸币业，两广总督张之洞曾于光绪十三年委托使英大臣在英国订购 全套造币机器，并在广东钱局首
铸机制银元和铜元。其
后，各省纷纷仿效，购制国外机械铸造银，这也使得使银币沾染上西方色彩。
& &近年来，随着收藏投资热的不断升温，银元也日渐走俏，且价格一路上扬。尤其是珍品银元，在藏品交易市场上表现异常活跃，也取得十分漂亮的成交记录。 银元材质珍贵，艺术价值高，由贵重金
属或白银合金铸造，制
作精美，图案考究，文字清秀，内容丰富，银光灿烂，其貌可人，也具有一定的保值和升值功能。随着收藏投资热的不断升温，银元在钱币市场中异常火爆，中国银元今后极大可能成为收藏投资领域中
的一匹&黑马&。
& &大清王朝是中国历史上最后一个封建帝制国家，辛亥一举推翻清王朝的统治，虽然清王朝统治期间遭受八国联军侵华，是历史上比较屈辱的一段，但是不可否认的是清王朝也给我们留下了浓墨重彩的
一笔，时至今日，
收藏品市场日益发展的今天，很多清王朝留下来的价值不菲的艺术品也渐渐浮现出来，其中不得不提的就是被誉为中国近代制币中的十大名誉品之一的光绪元宝银币，其市场价值已经高达百万。
& &因清代以来经历了多场战争，珍稀的光绪元宝损失严重，至今，数量已经极其有限。龙纹光绪元宝，这种元宝非常独特，它所代表的不仅仅是金钱，还有光绪年间的经济情况。为此，众多收藏家都纷
涌而至，以期能够找出
龙纹光绪元宝，以满足清代经济研究所需。
& &光绪元宝是大众收藏品，收藏者有一定数量，前期国内各区域都有实力型买家介入光绪元宝板块，在一定程度上控制了市场供货量，导致其价格快速走高。同时，光 绪元宝的价值也在同步上升。从
藏家和市民的接受程度
看，预计后期光绪元宝的价格还将继续上涨。光绪元宝记载了我国一段的历史，具有重要的文化意义和收藏价值。
& &清代末期是一个银币、纸钞、铜币并行的年代，而至嘉庆年间才开始发行新式银元，直至光绪年间金、银币才较为广泛的铸行。据悉，两广总督张之洞曾于光绪十三年委托使英大臣在英国订购全套造
币机器，并在广东钱局
首铸机制银元和铜元。其后，各省纷纷仿效，购制国外机械铸造银、铜元，而光绪元宝就在这个时期应运而生。
& &由于晚清的光绪元宝和大清元宝均采用了各种龙形作为背面图案，且龙型变化多样，作为龙的传人，不少铜元爱好者更加偏爱清末铜元，而不是民国时期带有强烈政治意味图案的铜元。
多位清帝在位时发行过铜币来作为流通货币，铜币的使用具有重要的现实意义和历史意义，使交易逐渐便利起来。其确实风格独特，文化内涵丰富，是不可多得的珍稀之品。
& &藏品铸工精美，品相较好，铜币包浆入骨，流通痕迹自然，边齿对，具有极高的投资价值和收藏价值。它有着历史熏陶，是价值很高的文物，具有深远的历史纪念意义；同时，还是考古和研究中国历
史文化难得的实物。
& &经过十余年的培育，以机制币为代表的钱币拍卖市场终于在大放异彩。即便与海外市场相比，当前内地市场亦不逊分毫。收藏者、投资者群体的知识更丰富、视野更开阔，观念也发生了深刻变化，他
们对藏品追求更苛刻，
在珍、稀的前提下，更看重藏品的完美品相和未来价值。
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（原标题：厉害| 她穿戴过的没有一件不火！搭配功底实在太深）
来自西班牙马德里的博主Maria Bernad在夏季的时候海豹君有介绍过，别看她年纪小，搭配功底却是很深，而且独有的范让人着迷。和是她个人的两大代表单品，硬朗的套装她用夸张的配饰和包包来中和，工业风十足的连体装混搭上蜡笔色的鞋包，一下子就年轻时髦了。抢眼的项链和吸睛满分的耳环为她的造型增分不少，颜色鲜艳的衣服搭配简洁的配饰，整体看来十分高级。况且她除了衣着出色，对配饰的敏感度更是好，“包”治百病说的就是她，看看她近期私照给你种草了没？
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分享至好友和朋友圈373建材网_建材招商加盟_建材代理_建材行业信息_中国建材网
地板315服务调查 | 生活家夺第一 设计服务是弱项
核心提示：【373建材网】 2017年12月-2018年2月，记者调查人员以消费者的身份，对15家地板品牌的官网、微信、天猫渠道进行调查，并在北京、【373建材网】 2017年12月-2018年2月，记者调查人员以消费者的身份，对15家地板品牌的官网、微信、天猫渠道进行调查，并在北京、上海、广州、深圳、佛山实地走访了这15家地板品牌的线下门店。
2017年12月-2018年2月，记者调查人员以消费者的身份，对15家地板品牌的官网、微信、天猫渠道进行调查，并在北京、上海、广州、深圳、佛山实地走访了这15家地板品牌的线下门店，进行了一轮地板行业&O2O体验&。在本次调查中，生活家地板以91分的成绩夺冠，大自然地板和贝尔地板以89分并排第二。从整体来看，地板行业离新零售还存在一段距离，大部分企业官网、微信渠道服务建设，尤其是咨询回复情况不佳，线上线下产品不同款，成为地板行业O2O硬伤。(说明：以上得分排名仅针对本次调查，综合得分由线上+线下成绩相加，了解具体评分规则)线上服务：60%微信无回复新零售概念风靡传统行业，线上线下的融合趋势也已经成为共识。对于注重消费体验的地板行业，从线上能否获得线下门店信息及购买指引?调查人员选取了官网、微信、天猫3个渠道进行调查，只有安信、菲林格尔、书香门地、圣象这4个品牌在3个渠道都能直接查询到门店信息。15家地板品牌中，11家品牌可以从官网直接获取门店信息，8家品牌可以从微信直接获取门店信息，9家品牌可以从天猫页面直接获取门店信息，天猫旗舰店大部分的门店信息是在门店特权定金页面。咨询客服的情况也不是很理想。调查人员在官网、微信和天猫进行咨询，询问门店地址、线上产品与线下产品是否同款等问题，只有大自然、必美、安信3个线上渠道都可以在1小时内提供详细的信息指引。天猫的回复情况最佳，除了富林地板天猫店升级，大部分地板品牌的天猫客服，都能做到秒回信息，并在10分钟之内回复有效信息。但是，调查人员也有遇到懵的客服：在天猫页面明明就有门店信息，客服却说不能提供实体店的地址和联系方式。官网的咨询入口五花八门，页面窗口、QQ登录直接咨询、加QQ好友，留言咨询，但是，调查人员还是吃了很多闭门羹，留言无回复，QQ无回复，或者根本不添加好友，甚至官网就没有线上咨询入口。只有安信、生活家、必美、扬子这4个品牌的官网客服搭理了调查人员。在地板品牌的官方微信留言，大部分也是石沉大海，只有6家品牌的微信公众号回复有效指引信息，60%微信无回复。调查人员就纳闷了，明明当天你就发了推送，就没有一点空看一下后台的留言，运营意识都到哪去了?有些品牌不同渠道的客服，回复的内容也有矛盾的地方。比如，贝尔地板的微信客服说门店产品和天猫产品都是一样的，天猫客服说线上线下款式都不同，导购说有部分同款。遇到这种情况，调查人员按照线上线下部分同款处理。线下门店：设计服务是弱项家居消费具有低频、高客单、重体验的特性，线下品牌专卖店仍是购买体验的重要场景。在2018家居行业&O2O体验&大调查中，网易家居首度深入线下，优先选择企业在当地的大店，对北上广深佛5大城市的企业门店综合服务能力进行考察。地板店面走访调查得分呈阶梯式分布，关键在于店面的定位和功能，一些店面能够满足基本的建材采购需求，同时也有一些品牌大力投入体验式营销，能提供设计服务和场景式体验，这也是品牌之间得分的差距所在。在走访的15地板品牌专卖店中，大部分门店装修简洁大方，产品相对丰富，能满足对比性的选择需求，有适合的交流洽谈空间，必美地板有比较有设计感的空间。这次走访的地板门店均无AR或VR体验。在产品讲解方面，大部分导购对产品各项性能及相关知识熟悉，讲解专业到位，能根据用户需求提供选购建议。在门店服务态度上，门店导购基本都能做到礼貌亲切，为客户提供合理化建议。生活家地板、大自然地板、必美地板等门店的导购都非常热情，能站在客户的角度考虑问题，对调查人员提出的问题，也耐心回答。而在设计服务方面，贝尔和肯帝亚门店的导购表示，可以下定之后出效果图，其他都是导购凭个人经验推荐地板的花色。贝尔地板的表现比较突出，导购根据现代简约风格的装修需求，每款地板上都有相应的二维码，可以扫描之后查看3D效果。调查人员询问可不可以根据户型出效果图，导购立即打电话给工厂的设计师让帮忙出图，设计师表示，后期提供cdr格式的户型图，可以出3D效果图。在离店之后，导购也主动联系，提醒可以用某个设计软件查看相关户型的地板效果。圣象地板则提供各种风格图纸，放在地板上面进行搭配，直观呈现地板搭配效果。而大多数地板门店现场也没有产品效果图册可以参考，门店的设计服务主要看导购的水平了，地板行业的设计服务还有待提高。线上线下融合：没有一家走通O2O在本次315调查中，记者调查人员通过走访了线下门店，也进一步印证地板行业的O2O现状。从调查结果来看，大部分地板企业在线上线下融合这方面，并没有走通。线上平台与线下实体店各自为战，甚至相互排斥。在产品方面，大部分品牌的地板线上线下产品不同款，电商专供成为常态。在这次调查中发现，安信地板、肯帝亚地板、久盛地板、扬子地板、世友地板等品牌的线上线下产品都不同款。大自然地板、贝尔地板、必美地板等品牌，则是线上线下部分同款。对于线上产品的体验，大多品牌选择的是为消费者寄样板。天猫平台的特权定金，是地板行业O2O的一个连接点。消费者可以在天猫上购买特权定金，比如10元抵200元，到指定的线下店面核销，门店可以通过阿里巴巴千牛软件生成订单，客户也可以在天猫上按阶段付款。特权定金实际上只承担了从线上到线下引流的作用。而且，特权定金并不是所有门店都适用。有些地板品牌在线上线下相互引导方面做了一些工作，但并没有真正打通。安信地板线下有一小部分O2O专区，与门店款式不一致,门店导购表示是配合总部的O2O，需要在线上下单，门店并不销售。导购也并不推荐购买O2O的产品。而菲林格尔地板在天猫上有地板商品，但是客服不让下单，只能拍下特权订金抵扣券，实体店核销下单订购。而更多的是，线上线下各自为战。门店导购对于电商的态度，大多还是保持排斥的态度。有品牌专卖店的导购告诉调查人员，天猫上的产品不好的，都是小板，原料都是木材的边边角角，好的木材都用在实体店的产品。整体来看，地板行业在线上渠道的布局，只有天猫旗舰店的运营较为成熟，而官网、微信的线上服务还有待提高。此次调查的地板品牌门店，服务均都在中上水平，设计服务是地板行业的硬伤。在线上线下融合方面，地板行业并未走通O2O，线上线下不同款或者只有少部分同款是常态。(来源：网易家居)
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DS80C320内存接口时序-DS80C320 Memory
来源：本站整理 作者：佚名日 15:38
[导读] Abstract: This application note addresses the Dallas Semiconductor DS80C320 high-speed microcontroller when used with external program memory. Due to the high speed of this device, critical memory interface timing constraints are examined.
Abstract: This applicaon note addresses the Dallas Semiconductor DS80C320 high-speed microcontroller when used with external program memory. Due to the high speed of this device, crical memory interface ming constraints are examined. This applicaon note discusses the DS80C320, but is applicable to all Dallas Semiconductor Microcontrollers.
IntroductionDallas Semiconductor's DS80C320 processor provides extensive new application opportunities due to its increased throughput. The increased speed, however, also requires attention to the timing requirements of the memory that interfaces with the processor. This application note identifies the critical timing paths associated with the memory interface and identifies memory speeds required for various CPU crystal frequencies.A typical configuration for a DS80C320 processor system is shown in Figure 1. A 32K x 8 EPROM is used to hold program information, and a 8K x 8 Static RAM is used for data storage. The Least Significant Byte (LSB) of the memories' address is time multiplexed with data on processor pins AD7 through AD0. The signal ALE from the processor goes high before a new address is placed on the bus and goes low before it is removed. In Figure 1, the action of ALE going low is used to latch the address into a 74HCT373 8-bit transparent latch. The 74HCT373 then provides its latched address output to the memories while the AD7 through AD0 CPU bus carries data. The MSB of the address is not multiplexed, and is available on port pins P2.7 through P2.0 (A15-A9).Figure 1. A typical DS80C320 system confirguration.
Program MemorySome of the signals used in interfacing the DS80C320 with EPROM Program memory are shown in Figure 2. As can be seen, timing relationships for two latch technologies (HCT and F) are shown. The technology selected for this latch is critical to the memory selection. The 74HCT373 has a worst case propagation delay from input to output (D to Q) of 44 ns while the 74F373's is 8 ns. This results in significantly different memory address access timing requirements depending on the family used. Examining timing parameters from the DS80C320 data sheet reveals that an instruction must be ready to read into the processor within 60 ns (parameter itAVIV1=3tCLCL-27)1, assuming a 33 MHz clock2. If the 44 ns propagation delay through the HCT latch is subtracted from this, you arrive at a required address access time of 26 ns.Figure 2. Program memory interface timing. While EPROM devices with access times of 26 ns or less may be available, they are likely to be expensive. A simple and more cost effective approach to solving this timing constraint is to use a fas an 74F373 for instance. Using the same analysis as above, if the propagation delay of the F373 latch, 8 ns, is subtracted from the tAVIV1 parameter (64 ns) you arrive at an address access requirement of 56 ns. This is much easier to realize than 26 ns.There is another timing constraint that suggests the use of an "F" type part in faster applications. On a 74HCT373 latch, the minimum required hold time of the input after the latch enable (ALE) goes low may be as much as 13 ns. The latch's input, the address out of the processor, is held until it is driven by the memory's output. This output is enabled by active-low PSEN. Again referring to the data sheet, it can be seen that active-low PSEN may occur as quickly as 0.5 ns after ALE falls (parameter tLLPL). If the memory's output begins to drive the bus immediately after active-low PSEN enables it, then there may only be 0.5 ns hold time. That obviously violates the latch's requirement. While it is reasonable to assume that there will be some delay before the memory's output will drive the bus, this is not a specified (or tested) parameter. Therefore a conservative estimate of 5 ns will be assumed. From above numbers and the equation for the tLLPL parameter (0.25tCLCL-7), it can be calculated that clock frequencies of 19.23 MHz and below will allow sufficient hold time to satisfy the 74HCT373 latch's requirement. Note that the hold time for a 74F373 latch is 3 ns which is met under all conditions.From the above analysis, you could choose 19.32 MHz as the latch technology switchover point, however, there is a reason why this was not done. Referring back to the address access equation (3tCLCL-24), it can be calculated that if a 74HCT373 latch is used for frequencies higher than 16.31 MHz, then a 90 ns or faster memory device is required. Therefore as a trade-off between latch speed and EPROM speed, the 74F373 latch (less expensive than a fast EPROM) is recommended for crystal frequencies greater than or equal to 16.31 MHz, and the 74HCT373 for lower frequencies.As shown in Figure 1, active-low PSEN enables the EPROM's output, so the timing for this signal must also be considered when choosing a device. The DS80C320 data sheet specifies the time from active-low PSEN low to a valid instruction in must be no more than 70 ns (parameter tPLIV). This is therefore the maximum allowed access time from the memory's active-low OE pin. In summary, the two timing requirements for the selected EPROM are that the address access time must be less than 92 ns and the active-low OE access time must be less than 70 ns. When looking at EPROM data sheets, it can be seen that common access time combinations (address access, active-low OE access) are 55,35; 70,40; 90,40; 120,50; 150,65; 200,75; and 250,100 ns. The 55, 35 device meets both timing requirements for a 33 MHz clock on the DS80C320 and is the recommended selection.Table 1 shows the slowest EPROM memory speeds recommended for various processor clock frequencies. If for some reason it is desirable to use devices faster than those recommended, this is possible. For this document, the memory speeds available (maximum access times from address and active-low OE respectively) are assumed to be those indicated above, however, any combination that meets the two requirements may be used. In Table 1, the memory speeds shown in bold are the recommended configurations.Table 1. Recommended EPROM speeds
1.8432 and below
250 nsIt should be noted that it is often possible to reduce the power consumption of EPROMs by keeping the active-low OE pin held active and controlling the device with the active-low CS pin. When doing this, however, the access time from active-low CS must be more closely considered. The active-low CS access time is often nearly the same value as the address access time (i.e., much slower than active-low OE access). If power consumption is the prime system consideration, a faster device may be selected, and the active-low CS used to select the chip.
Data MemoryChoosing a data memory (RAM) device to interface to the DS80C320 is much easier than choosing an EPROM device because of the flexibility designed into the processor. The DS80C320 provides a unique feature that allows the application software to adjust the speed at which data memory is accessed. The processor is capable of performing a MOVX instruction in as little as two instruction cycles (eight oscillator clocks). However, this value can be "stretched" as needed so that both fast memory and slow memory or peripherals can be accessed with no glue logic. On power up, the DS80C320 defaults to a stretch value of one resulting in a three cycle MOVX instruction. This default condition is a convenience to existing designs that may not have fast RAM in place. For the user who needs maximum performance, a stretch value of zero may be selected by software, resulting in a two machine cycle MOVX instruction. Even in high speed systems, it may not be necessary or desirable to perform data memory accesses at full speed. Additionally, there are a variety of memory mapped peripherals such as LCD displays or UARTs that are not fast enough to keep up with the full speed DS80C320. This flexibility allows the user to trade some performance for slower data RAMs if so desired.For maximum performance, i.e., with a two machine cycle data memory access programmed into the processor, the fetch of a MOVX instruction takes one machine cycle leaving one machine cycle for the memory read or write. For the analysis of the data memory's timing requirements that follows, it will be assumed that the recommendations of Table 1 have been followed. This implies that a 74F373 latch is used for clock frequencies above 16.31 MHz. A diagram of a single cycle data memory read is shown in Figure 3 and a single cycle data memory write is shown in Figure 4.Figure 3. Data memory read. Figure 4. Data memory write. Note that the term tMCS is used in the data sheet and in the equations that follow. It is a term that represents the time interval added for each stretch cycle. For example, if stretch is 0, then tMCS is zero and the equation remains the same. If stretch is one then tMCS equals 2tCLCL, and the equation is increased by this amount. The value of tMCS is increased by 4tCLCL for every additional stretch cycle.Through analysis, it can be determined that there are four SRAM timing parameters that are necessary and sufficient to meet the timing requirements of the DS80C320 in most situations. For the following discussion of these requirements, the worst case timing conditions, i.e., a 33 MHz clock and zero stretch cycles, have been used. For a data read operation, the DS80C320 expects the time from an address change until valid data is available to be 64 ns (tAVDV1=3tCLCL-27) or less. If the propagation delay from D to Q of a 74F373 latch (8 ns) is subtracted from this parameter, you obtain a memory address access (tAA) requirement of 56 ns. Also for a read, the DS80C320 expects the time from the active-low RD signal going low until valid data is received from the memory to be 35 ns (tRLDV=2tCLCL-25) or less. Since the processor's active-low RD signal is tied to the memory's active-low OE pin, the memory must have an output enable access time (tOE) of less than 40 ns. After the DS80C320 has read the data, the SRAM must relinquish the bus within 25 ns (tRHDZ=tCLCL-5). This dictates that the SRAM parameter tOHZ be less than 25 ns. For a write, the processor will provide a minimum write pulse of 49 ns (tWLWH=2tCLCL-11), which is equal to the required minimum write pulse width (tWP) of the SRAM. On the basis of these four calculated parameters and assumed SRAM speeds shown in Table 2, the appropriate speed device may be determined for a number of different clock frequencies. A summary of the recommended RAM speeds is given in Table 3.Table 2. Available RAM parameters
150Table 3 illustrates the point that even with a 33 MHz clock, relatively slow SRAM devices may be selected if a single stretch cycle (default condition) is used. If performance is not the primary system consideration, or if it is but data memory accesses are an insignificant part of the overall processing requirements, the use of a stretch cycle may allow a more cost effective solution.Table 3. Recommended RAM configuration
1.8432 and below
Additional ConsiderationsIn developing this application note, it was noted that some EPROM devices have extremely long "turn off" times. If the EPROM selected for 33 MHz systems has an "output disable to float" time greater than 25 ns (parameter tPXIZ=tCLCL-5), bus contention will occur on the processor's AD7-AD0 bus. In most situations, this simply results in higher power consumption. However, in some situations the address setup time to the memory can be affected necessitating a faster memory. The simplest solution to this problem is to use a device with the required turn-off time, but another possible solution exists. A 74F244 driver can be placed between the EPROM's output and the processor's data bus as shown in Figure 5. The 74F244's outputs turn off within a maximum of 8 ns, thereby releasing the processor's bus almost immediately and eliminating the contention.Figure 5. Fast EPROM turnoff. All of the timing calculations used in this application note are based on the equations in the DS80C320 data sheet. The timing specifications given in the data sheet assume an approximately equal capacitive load on the signals specified. If the configuration of Figure 1 is used, this is achieved. If, however, any signal is connected to additional loads, then the capacitive loading including the additional devices should be evaluated. If there is a significant difference, additional margins should be used in the critical path analysis, and appropriate memory speeds selected.For older or otherwise unconventional SRAM devices, it may be wise to confirm other important timing parameters such as data setup before write active. With the devices surveyed, meeting the four parameters discussed above will qualify the device for use.
Equation SummaryFor the user who wishes to calculate the memory speed requirements using a crystal frequency not shown in the preceding tables, the following equations provide a concise summary of the information needed. These times are for zero stretch cycles. The memory devices selected must have an address access time (based on the use of an F373 or an HCT373), an active-low OE access time, a active-low WE time, and a bus release time less than or equal to the calculated values. Note again that tCLCL is the period of the clock.1. For details on the equations presented in this document, refer to the DS80C320 data sheet.2. tCLCL is the period of the crystal frequency, and is equal to 30.3 ns for a 33 MHz crystal.
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