# hw

* [CPU](#cpu)
* [Endianness](#endianness)
* [Protection ring](#protection-ring)
* [UEFI Shell](#uefi-shell)
* [Buses](#buses)
* [Infini Band](#infini-band)
* [Raspberry PI](#raspberry-pi)
  * [Console](#console)
* [Resolution](#resolution)
* [Screen](#screen)

## CPU

CPUID to arch: <https://github.com/mer-tools/oprofile/blob/master/libop/op\\_hw\\_specific.h#L119\\>
CPU flags meaning: <http://unix.stackexchange.com/questions/43539/what-do-the-flags-in-proc-cpuinfo-mean>

## Endianness

<https://www.cs.umd.edu/class/sum2003/cmsc311/Notes/Data/endian.html\\>
In big endian, you store the most significant byte(MSB) in the smallest address.\
In little endian, you store the least significant byte(LSB) in the smallest address

## Protection ring

![](https://en.wikipedia.org/wiki/File:Priv_rings.svg)

## UEFI Shell

<https://software.intel.com/en-us/articles/uefi-shell>

```
map # list disks
help bcfg
```

## Buses

VESA (Video Electronics Standards Association)

<https://en.wikipedia.org/wiki/List\\_of\\_device\\_bit\\_rates>

|Technology|Rate||Year| |---|---|---| |ISA 16-Bit/8.33 MHz|66.7 Mbit/s|8.33 MB/s|1984 (created)| |I²C|3.4 Mbit/s|425 kB/s|1992 (standardized)| |Low Pin Count|125 Mbit/s|15.63 MB/s \[x]|2002| |HyperTransport 3.1 (3.2 GHz, 32-pair)|409.6 Gbit/s|51.2 GB/s|2008| |Unified Media Interface 2.0 (UMI 2.0; ×4 link)|20 Gbit/s|2 GB/s \[z]|2012| |Direct Media Interface 3.0 (DMI 3.0; ×4 link)|40 Gbit/s|4 GB/s \[z]|2015| |AGP 8×|17.066 Gbit/s|2.133 GB/s|2002| |AGP 8× 64-bit|34.133 Gbit/s|4.266 GB/s|| |PCI 32-bit/66 MHz|2.133 Gbit/s|266.7 MB/s|1995| |PCI 64-bit/100 MHz|6.4 Gbit/s|800 MB/s|| |PCI-X QDR|34.133 Gbit/s|4.266 GB/s|| |PCI Express 2.0 (×32 link)\[43]|160 Gbit/s|16 GB/s \[z]|2007| |PCI Express 3.0 (×32 link)\[44]|256 Gbit/s|31.51 GB/s \[y]|2011| |QPI (9.6GT/s, 4.8 GHz)|307.2 Gbit/s|38.4 GB/s|2014|

<https://en.wikipedia.org/wiki/NVLink>

## Infini Band

<https://en.wikipedia.org/wiki/InfiniBand>

|                                                   | SDR       | DDR  | QDR  | FDR10   | FDR         | EDR      | HDR      | NDR        | XDR    |
| ------------------------------------------------- | --------- | ---- | ---- | ------- | ----------- | -------- | -------- | ---------- | ------ |
| Signaling rate (Gbit/s)                           | 2.5       | 5    | 10   | 10.3125 | 14.0625\[6] | 25.78125 | 50       | 100        | 250    |
| Theoretical effective throughput, Gbs, per 1x\[7] | 2         | 4    | 8    | 10      | 13.64       | 25       | 50       |            |        |
| Speeds for 12x links (Gbit/s)                     | 24        | 48   | 96   | 120     | 163.64      | 300      | 600      |            |        |
| Encoding (bits)                                   | 8/10      | 8/10 | 8/10 | 64/66   | 64/66       | 64/66    | 64/66    |            |        |
| Adapter latency (microseconds)\[8]                | 5         | 2.5  | 1.3  | 0.7     | 0.7         | 0.5      |          |            |        |
| Year\[9]                                          | 2001,2003 | 2005 | 2007 | 2011    | 2011        | 2014\[7] | 2017\[7] | after 2020 | future |

## Raspberry PI

```
/opt/vc/bin/vcgencmd measure_temp
```

### Console

/dev/ttyAMA0

```
Speed (baud rate): 115200
Bits: 8
Parity: None
Stop Bits: 1
Flow Control: None
```

## Resolution

```
SQCIF = 128x96
QCIF = 176x144
QVGA = 320x240
CIF = 352x240/288
HVGA = 640x240
VGA = 640x480
2 CIF = 704x240/288
4 CIF = 704x480/576
D1 CROPPED = 704x480/576
D1 = 720x480/576

D1 (525) 720 x 480 is in NTSC
D1 (625) 720 x 576 is in PAL

720p is 1280 x 720. (921,600 total pixels)
1080p is 1920x1080. (2,073,600 total pixels)
3MP is 2048 x 1536. (3,145,728 total pixels)
5MP is 2560 x 1920. (4,915,200 total pixels)
```

## Screen

| Name                              | Wiki                                                         |
| --------------------------------- | ------------------------------------------------------------ |
| OLED                              | <https://en.wikipedia.org/wiki/OLED>                         |
| microLED, micro-LED, mLED or μLED | <https://en.wikipedia.org/wiki/MicroLED>                     |
| Mini LED                          | <https://en.wikipedia.org/wiki/LED-backlit\\_LCD#Mini\\_LED> |