IBM 360-30 1401 Circa 1965

Here is the Main computer IBM-360-30-1401 panel

Brief and short computers History

During WWII in England there was the first special computer call COLOSSUS
this was used to help decipher the German encoded messages using the Enigma machine or the Lorentz cypher.

Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations
and was very big use a lot of elecrical energy around 15 KW.
Colossus was programmed by switches and plugs and not by a stored program.

Memory was done with some vacuum tubes / Flip Flop registers
very limited in numbers of bits of memory.

There was not any Operating system or programs in memory.
Some of the calculations were done in parallel.

see wiki

The first electronic succesfull commercial computer by IBM.

Around 1955 IBM USA started working design on a new generation of electronic computer using transistor instead of Vacuum tubes.

Main advantages was that it use a lot less energy , system was a lot smaller , memory use magnetic Ferrite core.

The magnetic Ferrite cores was small but to get 4 Kbytes needed 32,000 ferrites cores and was very expensive.

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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).

CPU Memory

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.


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here is a sort of early modem for the 1401 CPU

very primitive communication using phone line and the CPU

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IBM card reader model 129

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IBM 1401 Dumb terminal with Keyboard

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IBM Card reader 1402

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IBM Hard Disk drive 7.25 Mbytes

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IBM Line printer 1403

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IBB Magnetic tape
using reel 1200 Ft or 2400 Ft with around 200 Mega Bytes

here is a Mag Tape tester

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IBM printer Model 25

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General layout for an IBM 1401 computer system

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some examples of SMS card

an IBM driver PCB

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an IBM driver PCB

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Omg. Would u look at that! 7 mbs wow!

what do you mean ?

not much comparison to the PC we got nowadays LOL

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