gosman的博客

虽然现在FPGA(现场可编程门阵列)这么火，但我相信一定有很多人，不知道FP(现场可编程)的定义吧。我把在维基百科(这几天竟然能上了，真奇怪啊)找到的定义摘录下来，做个备忘，呵呵。

好不容易找到对这些电源标号区别的详细解释，呵呵。现在网上的那些解释不是错误就是不详尽，呵呵。找个时间，把它翻译成中文的，呵呵。

Almost all integrated circuits (ICs) have at least two pins which connect to the power rails of the circuit they are installed in. These are known as the IC's power supply pins. However, the labeling of the pins varies by IC family and manufacturer.

The simplest labels are V+ and V−. However, internal design and historical tradition have led to a variety of other labels being used. Also, V+ and V− may be confused with the + and − voltage inputs to ICs like op amps.

Sometimes one of the power supply pins will be referred to as ground. In digital logic, this is nearly always the negative pin; in analog integrated circuits, it is most likely to be a pin intermediate in voltage between the most positive and most negative pins ^{[citation needed]}.

Double subscript notation uses similar looking placeholders with subscripts. In that notation the subscripted letters denote two points.

History

V_CC (note: lower case is often used instead of subscript, e.g. "Vcc") is an electronics designation that refers to voltage from a power supply connected to the "collector" terminal of a bipolar transistor. In an NPN bipolar junction transistor, it would be +V_CC, while in a PNP transistor, it would be −V_CC. There is debate over the origins of the double letter subscript naming convention. One proposal is that it originated as an abbreviation of the supply voltage for a common collector amplifier with the other power supply names mimicking this fashion. Double letters may also have been used to clearly indicate that a power supply voltage is being referred to.

In general, double letter subscripts refer to power supply voltages. For example, V_EE refers to the "emitter" voltage as supplied by the power supply pin. In NMOS logic, V_SS refers to the "source" voltage, and V_DD is the "drain" voltage likewise.

Within a circuit, single letter subscripts refer to that voltage relative to ground; for example, V_C is the "collector" voltage relative to ground. Two different letters indicate the voltage between two terminals; for example: V_BE is the "base" to "emitter" voltage drop, while V_CE is the "collector" to "emitter" voltage.

Modern use

CMOS ICs have generally borrowed the NMOS convention of V_DD for positive and V_SS for negative despite the fact that both positive and negative supply rails actually go to source terminals (positive supply goes to PMOS sources, negative supply to NMOS sources). ICs using bipolar transistors have V_CC (positive) and V_EE (negative) power supply pins.

In single supply systems (e.g., most modern digital and analog circuits) the negative power supply pin is also commonly referred to as GND. In "split rail" supply systems (e.g., older analog circuits) positive, negative and ground power supply pins are used.

More advanced chips will often have pins carrying voltage levels for more specialized functions in or out of the chip and these are generally labeled with some abbreviation of their purpose. For example V_BUS for the 5 volt supply needed for a bus-powered USB device or V_ref for the reference voltage for an analog-to-digital converter.

这几天在学习 emacs 中最头疼的就是一大堆的命令，为方便以后查询，将学习中遇到的每个命令都记录在了 Google Spreadsheet。现在把它放在博客上，希望对大家也有帮助：），现在命令还不多，随着学习的深入，命令会逐渐增多，该表格会由 Google Spreadsheet 自动更新。

命令查询

试了一下永中 Office，我就把 OpenOffice 卸掉了。用 OpenOffice 打开中文 Word 文档总是"变形"，永中 Office 就没这问题，我需要的只是能够正常浏览 doc 和 ppt 而已。永中 Office 用 Java 开发，正式版是要收费的，但提供试用版免费下载使用，虽然是试用版，但完全不影响使用。如果不介意永中不是自由软件的话，这个软件很值得一试哦。反正我是不想使用那臃肿的 OpenOffice。还有永中 Office 自带了一套中文字体，效果还不错。看张截图吧，界面很像 Microsoft 的 Office 哦。

下载: 永中集成Office2007简体中文试用版

由于 gnome-terminal 和 konsole 绑定的各种快捷键，妨碍了其他程序(如 mc，emacs)的使用，因此换用轻量虚拟终端程序 rxvt。我使用的是 rxvt-unicode，上网找了一些资料，把 urxvt 配置了一下。下面是我的 rxvt-unicode 配置，添加到 ~/.Xresouroces，中文字体使用的是文泉驿。

!! RXVT setting
URxvt.background:black
URxvt.foreground:gray60
URxvt.geometry: 90x25+180+200
URxvt.colorBD:yellow
URxvt.colorUL:green
URxvt.cursorColor:red3
URxvt.color0:black
URxvt.color1:red3
URxvt.color2:springgreen
URxvt.color3:wheat3
URxvt.color4:navy
URxvt.color5:magenta4
URxvt.color6:steelblue1
URxvt.color7:gray85
URxvt.color8:gray10
URxvt.color9:orangered2
URxvt.color10:chartreuse3
URxvt.color11:lightgoldenrod2
URxvt.color12:skyblue1
URxvt.color13:pink1
URxvt.color14:lightblue1
URxvt.scrollBar:False
URxvt.saveLines:3000
URxvt.font:xft:Bitstream Vera Sans Mono-12,xft:WenQuanYi Bitmap Song-12
URxvt.boldFont:xft:Bitstream Vera Sans Mono-12:Bold,xft:WenQuanYi Bitmap Song-12:Bold
URxvt.preeditType:Root

再执行以下命令，然后重启 rxvt-unicode 就可以了。

以下是我的截图：

参考：使用文泉驿点阵字体后，英文如何设定？