Rare! Vintage Mainframe Ferrite Core Memory 4096 Bytes of 1960s

Ferrite Core Memory Plate manufactured in the USSR at 1960s

Plate size (approx):5 x 5 inch

The board weighs approximately 0.3 pounds

Capacity:1 tiny ferrite core = 1 bit

A 64 x 64 core memory plate stores 4096 bit of data

CONDITION: excellentcondition without broken wires and missing cores

The heyday of ferrite memory was in the 50s and 60s of the last century. Before its appearance, all sorts of exotic devices that were poorly suited for mass use had to be used as computer memory devices - oscilloscope tubes, mercury delay lines, etc. Ferritearrays differed favorably from them, first of all, in their highest reliability and small dimensions. They lasted until the mass development of semiconductor integrated circuits, with which ferrites could not compete due to their lack of technological effectiveness (and, accordingly, price), and later - also the limited volume of stored information.

For data storage systems of digital machines, ferrites with nonlinear magnetic characteristics are used - ferrites with a rectangular hysteresis loop (RHL).

These ferrites are special in that the cores made from them can be in two stable states of magnetization - +B, which corresponds to the code "1", and -B, corresponding to the code "0" in the binary number system.

In order to remagnetize, for example, a ferrite rod or ring, it is necessary to create a magnetic field of a certain intensity. If the magnetic field has an intensity less than the threshold value H, then the ferrite will not remagnetize even with repeated and long-term application of this magnetic field.

The classic scheme for using ferrites with RHL for memory devices is based on the coincidence of half-currents, i.e. on the principle that under the action of a magnetic field H/2, thecoredoes not change its magnetic state, and under the action of a field H, it is completely remagnetized.

In this case, the random access memory device is a matrix of toroids through which conductors pass in two directions - current-carrying buses for exciting magnetic fields and a reading winding for removing information codes. In order to simplify the technology of matrix production, all toroid windings are made single-turn.

In order to record the code "1" in any toroid, it is necessary to excite a field H/2 in the buses at the intersection of which it is located. In the selected toroid, the ampere turns of both directions will add up and a field equal to H will act on it.

When recording the code "0", the exciting fields created by the buses x and y are supplied with a time shift, or all toroids are supplied with an additional winding, called the unit inhibition winding and designed to create a field of the opposite polarity to the recording field at the right time, equal to -H/2. The resulting field in both cases will be equal to H/2 and the toroid will not be remagnetized from the state.

When reading the recorded information from the toroid, it is necessary to excite a field of –H/2 using the buses intersecting in it. Then the toroid on which the code “1” was recorded will be remagnetized from the state +B to the state -B and the emf of the signal of the code “1” will be induced on the reading wire. The toroid on which the code “0” was recorded will not be remagnetized (will remain in the state -B) and the emf of the signal will not be induced on the reading wire.

It should be noted that the information is destroyed after it is read. To reuse the information in the machine, it must be restored (regenerated).

One reading wire and one inhibit wire are woven through all the cores. Thus, the matrix allows reading or writing bits only sequentially.

Ferrite cores were also used to build read-only memory units. Binary information was recorded in them during assembly, by appropriately flashing the cores with readout wires. In this case, the passage of a wire through the core is equivalent to a binary one, and the passage of a wire past the core means recording a binary zero.

Memory devices on magnetic ferrite cores are units consisting of a large number (up to hundreds of thousands) of ferrite ring magnets arranged in regular rows in the form of a flat or spatial lattice.

Each toroidal core is used to store one binary digit: zero or one. The cores are 1-5 mm in diameter (inUScomputers the minimum diameter reached 0.25-0.30 mm).

Sovietmemory units on ferrites, as a rule, were devices for private use, developed for each product separately and therefore were of limited circulation.

The exception was the so-called Memory Cubes, which found application in second- and third-generation computers, which determined their serial production and standardization.

Despite all the advantages of memory devices made on ferrite cores, they had a number of significant disadvantages. These disadvantages include:

- high labor intensity of manufacturing a numerical block: flashing the cores was an operation that required significant manual labor;

- the impossibility of replacing the core in case of its breakage; if it was necessary to replace one ring, it was necessary to re-flash a significant number of cores;

- strong influence of the ambient temperature on the properties of the cores, in particular, on the width of the hysteresis loop;

- the need to return the cores to their original state;

- self-heating of the cores caused by hysteresis losses, which limited the maximum operating frequency of the memory device;

- a large number of cores.

They tried to overcome these shortcomings both within the framework of traditional schemes - by complicating firmware schemes or using multi-winding cores - and by using new, advanced developments for that time. This is how memory devices on multi-hole plates, biaxes, layered ferrites and systems on thin magnetic films appeared. What is characteristic, the technological methods of manufacturing such systems (photolithography, vacuum and chemical deposition, etc.) anticipated semiconductor production.

But in fact, after the "explosive" development of integrated memory circuits, since the mid-70s, ferrite memory systems were used only in those areas where their advantages, such as resistance to radiation and electromagnetic interference, were critical - space systems, industrial equipment, etc.