Timeline of Binary Prefixes - 1980s

1980s

1980
  • Shugart Associates Product Brochure, published June 1980 specifies the capacity of its two HDDs using megabytes and MB in a decimal sense, e.g. SA1000 formatted capacity is stated as "8.4 MB" and is actually 256×32×1024 = 8,388,608 bytes.
  • Shugart Associates SA410/460 Data Sheet published October 1980 contains capacity specifications as follows:
Formatted Capacity SA410
Single/Double Density		 SA460
Single/Double Density
Per Disk 204.8/409.6 KBytes 409.6/819.2 KBytes
Per Surface 204.8/409.6 KBytes 204.8/409.6 KBytes
Per Track 2.56/5.12 KBytes 2.56/5.12 KBytes
Sectors/Track 10 10
  • Shugart Associates was one of the companies that invented the 5¼" FD using K in a decimal sense.
  • Note that the same data sheet uses MByte in a decimal sense.
1981
  • 8086 Object Module Formats
    • "The 8086 MAS is 1 megabyte (1,048,576)"
  • Quantum Q2000 8" Media Fixed Disk Drive Service Manual
    • "four models ... the Q2010 having an unformatted 10.66 Mb capacity on one disk platter and two heads, the ... 21.33 Mb ... 32.00 Mb ... 42.66 Mb"
    • (1024 tracks × "10.40Kb" per track = 10649 "Kb", which they write as "10.66Mb", so 1 "Mb" = 1000 "Kb")
    • (256 Bytes per sector, 32 Sectors/tk = 8192 bytes, which they write as "8.20Kb" per track)
    • "Storage capacity of 10, 20, 30, or 40 megabytes"
    • "4.34M bits/second transfer rate"
  • Apple Disk III data sheet
    • "Formatted Data Capacity: 140K bytes"
    • Apple uses K is a binary sense since the actual formatted capacity is 35 tracks * 16 Sectors * 256 bytes = 140 KiB = 143.360 kB
1982
  • Brochure for the IBM Personal Computer (PC)
    • "User memory: 16KB to more than 512KB", "single-sided 160KB or double-sided 320KB diskette drives"
IBM (July 1982). Technical Reference: Personal Computer Hardware Reference Library (Revised ed.). IBM Corp. pp. page 2–93. 6025008.
"The drives are soft sectored, single or double sided, with 40 tracks per side. They are Modified Frequency Modulation (MFM) coded in 512 byte sectors, giving a formatted capacity of 163,840 bytes per drive for single sided and 327,680 bytes per drive for double sided."
  • Seagate ST 506/412 OEM Manual
    • "Total formatted capacity ... is 5/10 megabytes (32 sectors per track, 256 bytes per sector, 612/1224 tracks)"
1983
  • IBM S/360 S/370 Principles Of Operation GA22-7000 includes as statement:
    • "In this publication, the letters K, M and G denote the multipliers 210, 220 and 230 respectively. Although the letters are borrowed from the decimal system and stand for kilo 103, mega 106 and giga 109 they do not have decimal meaning but instead present the power of 2 closest to the corresponding power of 10."
  • IBM 341 4-inch Diskette Drive
    • unformatted capacity "358,087 bytes"
    • "Total unformatted capacity (in kilobytes): 358.0"
  • Maxtor XT-1000 brochure
    • "Capacity, unformatted" 9.57 MB per surface = 10,416 bytes per track * 918 tracks per surface = 9,561,888 byte (decimal MB)
  • Shugart Associates SA300/350 Data Sheet published c. November 1983 (one of the first MIC standard 3.5" FDDs) contains capacity specifications as follows:
Formatted Capacity Single Sided
Single/Double Density		 Double Sided
Single/Double Density
Per Disk 204.8/409.6 kbytes 409.6/819.2 kbytes
Per Surface 204.8/409.6 kbytes 204.8/409.6 kbytes
Per Track 2.56/5.12 kbytes 2.56/5.12 kbytes
Sectors/Track 10 10
Shugart Associates, one of the leading FD companies used k in a decimal sense.
1984
The Macintosh Operating System is the earliest known operating system using the prefix K in a binary sense to report memory size and HDD capacity.
In the original 1984 Apple Macintosh ad, page 8, Apple characterized its 3½ floppy disk as "400K," that is, 800×512 byte sectors or 409,600 bytes = 400 KiB. Similarly, the February 1984 Byte Magazine review describes the FD as "400K bytes".
1985
Exabyte Corp. founded
September 1985. Apple introduced Macintosh Finder 5.0 with HFS (Hierarchical File System)along with the Mac's first hard drive, the Hard Disk 20. Finder 5.x displayed drive capacity in binary K units. The Hard Disk 20 Manual specifies the HDD as having
"Data capacity (formatted): 20,769,280 bytes
Bytes per block: 532 (512 user data, 20 system data)
Total disk blocks: 39,040
and has the following definition in its glossary:
megabyte

Approximately one million bytes (1,048,567) of information. A 20 megabyte hard disk holds 20 million bytes of information, or 20,000 kilobytes (20,000K)

Apple Hard Disk 20 Manual
Note the user data is 39,040 * 512 = 19,988,480 bytes.
1986
Apple IIgs introduced September 1986
ProDos16 uses MB in a binary sense.
Similar usage in "ProDOS Technical Reference Manual" (c) 1985, p. 5 & p. 163
Digital Large System Mass Storage Handbook (c) dated September 1986
"GByte: An abbreviation for one billion (one thousand million) bytes." p. 442
"M: An abbreviation for one million. Typically combined with a unit of measure, such as bytes (MBytes), or Hertz (MHz)." p444
1987
  • Seagate Universal Installation Handbook
    • ST125 listed as 21 "Megabytes" formatted capacity, later document seems to confirm that this is decimal
  • Disk/Trend Report – Rigid Disk Drives, October 1987
    • First use of GB in a decimal sense in this HDD marketing survey; Figure 1 states "FIXED DISK DRIVES more than 1 GB" market size as $10,786.6 million.
  • Webster's Ninth New Collegiate Dictionary (1987) has binary definitions for kilobyte and megabyte.
    • kilobyte n (1970): 1024 bytes
    • megabyte n (1970): 1,048,576 bytes
1988
  • Imprimis Wren VII 5¼ Inch Rigid Disk Drive Data Sheet, printed 11/88
    • "Capacity of 1.2 gigabyte (GB)"
1989
  • IBM Enterprise Systems Architecture/370, Reference Summary (GX20-0406-0), p50 (the last page), has a two table, one to recap the decimal value of power of 2 and 16 to 260, and one that read:
Symbol Value
K(kilo) 1,024 = 210
M(mega) 1,048,576 = 220
G(giga) 1,073,741,824 = 230
  • Electronic News, September 25, "Market 1.5GB Drives"
    • "Imprimis and Maxtor are the only two drive makers to offer the new generation of drives in the 1.5GB capacity range…"
    • "IBM, Hewlett-Packard, Fujitsu, Toshiba, Hitachi and Micropolis are expected to enter the market for 1.5GB capacity…"

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