IBM computers and devices / early history
IBM 360 - 30 / 1401
Date: Circa 1965
IBM_S/360 model 30 $133 000 Circa 1965
A raised floor typical of the mainframe era (and modern data centers), used to hide cabling and distribute cooled air
but the IBM 1401 could be rented for $2500 per month, opening up the market
started at US$2,500 (worth about $21,487 today).
Properties of ferrite cores memory
The 1401 had a 11.5 microsecond memory cycle time,
compared to 5 nanoseconds for modern RAM.
While the 1401 CPU had 4000 characters of storage (expandable to 16K model 1402 12 KBytes),
Adding a 4K memory expansion to the 1401 cost $20,100 ($162,000 in current dollars).
The magnetic core memory was small and very expensive compared to today’s ships in Gigabytes!
the memory read write / cycles was around 11.5 microseconds cycle time.
The cores were about 1 mm in diameter and used a four-wire arrangement ( x rows , y columns , sense, and inhibit )
The additional modules were contained in an add-on box, with 4 KB to 12 KB extra magnetic fores
the 1406 Core Memory Unit, which was about two feet square and three feet high
PCB cards = SSMS Card = Standard Modular System cards
Standard Modular System cards or SMS cards. These SMS cards, invented in the early years of transistorized computing,
each implement a simple circuit on a board about the size of a playing card use Germanium transistors.
Most cards use germanium-alloy transistors.
Most of the logic circuitry of the 1401 was a type of diode–transistor logic (DTL),
Other IBM circuit types used were referred to as: Alloy (some logic, but mostly various non-logic functions, named for the germanium-alloy transistors used),
resistor–transistor logic (RTL)).
SMS Card single-sided paper-epoxy printed circuit boards either 2.5 by 4.5 inches (64 by 114 mm) with a 16-pin gold-plated edge connector (single wide)
or 5.375 by 4.5 inches (136.5 by 114.3 mm) with two 16-pin gold-plated edge connectors (double wide).
Digital Integrated cirtuits did not exist yet and cmare later on in the 70’s.
The amount of logic on one card was similar to that in one 7400 series SSI or simpler MSI package
(e.g., three to five logic gates or a couple of flip-flops on a single-wide card up to about twenty logic gates or four flip-flops on a double-wide card).
The 1401 computer alone uses 162 different types of SMS cards.
At 79 cents of gold per board. In total, the 3047 SMS cards in an IBM 1401 contain $2400 worth of gold.