Mebibyte per second to Kilobit per second

dd uses binary units because Linux filesystems work in binary block sizes (4 KiB, etc.). Drive manufacturers use decimal MB/s because it makes speeds look about 5% higher and aligns with their decimal capacity marketing. A "550 MB/s" SSD shows roughly 524 MiB/s in dd.

Run "dd if=/dev/zero of=testfile bs=1M count=1024 oflag=direct" and it will report write speed in MiB/s. For read speed, use "dd if=testfile of=/dev/null bs=1M". The oflag=direct flag bypasses filesystem cache to measure actual disk performance.

No — 550 MiB/s is about 577 MB/s, and 550 MB/s is about 524 MiB/s. The ~5% difference means an SSD advertised at 550 MB/s will show around 524 MiB/s in Linux tools. It is not a defect or false advertising, just different unit systems measuring the same physical speed.

A RAID 0 stripe of two SATA SSDs gives roughly 1,000–1,100 MiB/s sequential reads. Four NVMe SSDs in RAID 0 can hit 12,000–14,000 MiB/s. RAID 5/6 arrays sacrifice some write speed for redundancy — expect 70–90% of raw stripe performance on writes.

Sequential reads let the drive stream data from contiguous locations, maximising throughput. Random I/O forces the controller to seek different addresses, adding latency per operation. An NVMe SSD might do 7,000 MiB/s sequential but only 50–80 MiB/s random (at 4 KiB block size), because the bottleneck shifts from bandwidth to IOPS.

Audio codecs compress sound into a stream of bits played back in real time, so the natural unit is bits per second. At 128 kbps, an MP3 encoder allocates 128,000 bits to represent each second of audio. Higher kbps means more data per second, better quality, and larger files.

Technically yes — dial-up ISPs like NetZero still exist in the US, and some rural areas with no broadband rely on them. But at 56 kbps, loading a modern webpage (average 2.5 MB) would take over 5 minutes. It is functionally unusable for anything beyond basic email.

At 128 kbps, the encoder discards more audio detail — cymbals sound washy, stereo imaging narrows, and quiet passages lose nuance. At 320 kbps, most listeners cannot distinguish the MP3 from the original CD in blind tests. The file is 2.5× larger but audibly transparent to most ears.

A standard VoIP call uses 8–64 kbps depending on the codec. The widely used Opus codec delivers excellent voice quality at 16–32 kbps. Traditional landline phone calls used 64 kbps (G.711 codec). HD Voice on modern smartphones uses about 32 kbps with the AMR-WB codec.

The screeching was the modem handshake — two modems negotiating their connection speed by exchanging test tones over the phone line. Each phase of the screech tested different frequencies and protocols. The modems were literally talking to each other in audio, finding the fastest kbps rate the line could support.