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Digital ICs range from simple gates, to complex microprocessors. 74 and 4000 series perform a range of simple decision making and counting tasks, and do things like driving a single digit 7-segments LED display. They work with signals either at or near ground, or at or near the supply rail.
These are the two most common types of logic ICs. Most are housed in 14 or 16 pin dual-in-line (DIL) packages, with surface mount versions now available.
TTL is Transistor-Transistor Logic, which requires a positive 5 volt supply. It uses bipolar transistors. 74, and 74F are examples. It can operate at high switching rates, but uses more power than CMOS.
CMOS stands for Complementary metal-oxide-semiconductor. It uses both p-type and n-type FETs. Part numbers start with 40, or 74C, etc. While there are versions with a tighter voltage requirement, limited to 5.5 volts, and designed to work with TTL, 4000 and 74C series can work from 3 to 18 volts, and draw around the 8th the power of TTL.
With the exception of certain open-collector TTL products, both families actively drive low or logic 0 outputs towards ground, and high or logic 1 outputs towards the positive power rail. Open collector devices had rating from 15 to 70 volts, and were used to operate things such as NIXIE tubes, by pulling the active output(s) to ground.
See: Wikipedia: TTL and
54 are military grade TTL ICs with wide operational temperature ranges, and often well sealed ceramic cases. 64 and 84 were now rare industrial devices, with intermediate temperature tolerance. European and Soviet bloc countries had various alternative numbering systems. DM93 is a Fairchild series, which may be DTL; its power needs suggest this or TTL. MC6xx and FZH are discontinued High Threshold Logic families for use in electrically noisy industrial environments. There are / were also NMOS and PMOS, with interesting supply requirements.
A MMIC is a Monolithic Microwave Integrated Circuit, an IC designed to work at microwave frequencies.
The typical format of a MMIC useful for a TV or other masthead amplifier is a disc on cross form of leads; two grounds, the input, and the combined output and power input, as illustrated here: Wikipedia: MMIC. There are also mixers and other devices. They are also used in satellite TV LNBs (Low Noise Block down-converters), and cellular systems. For a deep dive, see this NASA article: MMICs
Op-Amps - Operational Amplifiers were originally designed to perform addition and subtraction in analogue computers. However, they are now more often used as audio amplifiers, and in active filters. They are still used in some instrumentation. They are part of a wider family termed "analog" or "linear" ICs. μA741 is an early, and famous example, although modern products have greater performance.
Many just have a plus and minus inputs, and an output, meaning two may be placed in a single 8 pin DIL package, along with the positive and negative pins. Others have Offset and Null pins. Single 5-pin surface mount versions are available.
Due to the fact things like audio signals often swing plus and minus, many op-amps use positive and negative supply rails, although this is certainly not compulsory.
Many use bipolar transistors, but JFET input devices are available, and BiCMOS is the latest trend.
There fall well within the definition of Differential Amplifiers. The latter having been built for many years, using triode valves / tubes, bipolar transistors, a hybrid of these, and FETs. These were uses in things like EEG and ECG recorders, where low frequency microvolt signals needed to be read in the presence of mains frequency hum, and other electrical interference. They are likewise used in PA mixing desks, fed by balanced audio cables, so stage light dimmers, air conditioning motors, and the like don't add hum, buzz, and other noise to low level microphone signals running 20 or more metres through a venue. Except for front ends in specialised recording pre-amplifiers, I expect all desks use IC op-amps now.
See: Wikipedia: Operational_amplifier and Wikipedia: Differential_amplifier
There are also ICs which perform things like voltage to frequency conversion, and the famous 555 timer, often used as as oscillator. Many linear chips have a 3 digit part number. For commercial / hobby grade they often start with a 3, such as the LM311, a comparator. LP311 is the low power, high impedance input version. 2xx indicates industrial temperature range, and 1xx military. Of course, if you are making something to go into a hot engine bay, you might pay up for the better grade IC, especially of its function is important.
Voltage standards and regulators, along with current sources, are also popular examples.
Part numbers on ICs may include prefix letters which indicate the manufacturer, and suffixes which indicate certain characteristics. While professional suppliers (RS, E14, etc) will list the exact part numbers and variations, at somewhere like Jaycar, the 4017 in the shop is whatever 4017 through-hole variant was cheap in the markets of Shenzhen (or wherever) a few months ago. I remember going to multiple Dick Smith stores once, looking through their parts trays for a UBC (un-buffered output version if a particular logic chip, instead of the usual buffered version, for a magazine project which was using it in a linear mode.
The functions of logic gates can be replicate using resistors, diodes, and transistors. Several inputs can be "ORed" together using diodes, with a positive voltage on any input flowing to the output. A transistor can perform a NOT or invert function. Put the two together, and you get a NOR gate. ANDs, and thus NANDs, work by having a pull-up resistor, and inputs pulled low via backwards facing diodes. Thus all inputs must he high to have a high on the output. An extension on diode based OR gates, the Diode Matrix can be used to programme a radio, or operate common cathode LED display (below). See: Wikipedia: DTL and Wikipedia: Diode Logic
Serial and parallel data, and VGA (analogue) computer video, among other PC connections used a D shaped connector with multiple pins. The first letter is a D, the second is the size of the housing, then a dash, and the number of pins. For the smaller sizes there are normally 2 rows, but the high-density (HD) version has 3. Examples are DE-9 and DB-25, both used for RS-232C serial data; and DE-15HD used for VGA. The DA-15 pin versions were used for joysticks, and there were or are various other uses for D connectors, including multi-channel audio, and a drive and image scanner interface called SCSI (in some cases using DC-37).
DD-78 is a large, 4 row high density version used on some very expensive commercial radios - the sort of things your taxes pay for to go into helicopters, so pigs can fly. There are also Double Density versions, with the same number of rows as the high density versions, and tighter spacing between pins within these rows, up to 100 pins. See:Wikipedia: D-subminiature
Applicable standards are: DIN 41652, IEC 60807-3, and MIL-DTL-24308.
Some RGB computer monitors, and some radios use a version with coaxial connections. High current pins for power fit the same shells. For the monitors the DB13W3 is used.
Beware the 23 pin version - soldering or crimping 20-odd wires before noticing the deficit of 2 pins may ruin your evening. 19 pin units also exist, as does the so-called DF-104.
Micro-D is a very compact version, secured using 2-56 (2.184 mm) screws, instead of the usual 4-40 (2.845 mm) ones. Even smaller is the Nano-D. Both are used in the military and space industries.
USB, or Universal Serial Bus is an interconnection system for PCs. Some modern transceiver include these for connection of a PC, often using the old square Type-B socket used on printers. A few include a Type-A connector to connect a keyboard. For others, a USB to serial port interface is needed, with CAT (Computer Aided Transceiver) being a variation on the Serial standard.
DIN stands for Deutsches Institut für Normung (German Institute for Standardisation), and they have standards for all manner of things, even Parker style pen refills; and DIN-476, now ISO 216, the A-series paper standard.
The DIN 41524 and related standards, specify a round connector with a 13.2 mm shell. More popular in the past, for audio and control signals, these have multiple pins. The most popular (defined in DIN 41524) has 5 pins arranged in a 180 degree arc, this having a diameter 7 mm. Designed for (unbalanced) stereo audio input and output, including on portable cassette recorders. The earliest PCs used this standard for keyboards. MIDI also uses it. Some CBs use these instead of the proper microphone connectors with the threaded locking ring, made by Marushin in Japan. MicroBees used a 5 pin DIN for power, video, and cassette connections.
DIN 41524 includes a 3 pin version for mono audio input and output. Other standard numbers define connectors with different pin arrangements, up to 8 pins, with more used on proprietary connectors. DIN 41529 defines a 2 pin loudspeaker connector.
There are also non-standard versions with retaining rings.
The 9.5 millimetre "Mini-DIN" was used for mouse and keyboard on the PS/2 and other computers of the era. They are also used on Yaesu radios for auxiliary audio and for control of the radio and/or external tuners.
Wandering off the exam: They also specify DIN rails which are often fitted within switchboards, at least in countries which are not the USA. The DIN 46277 "top-hat" version is pressed from 1 or 1.5 mm sheet, with a width of 35mm and a height of 7.5 mm. The base has a 27 mm external dimension. Extruded versions exist, as do plastic enclosures designed to be surface mounted in older switchboards to add DIN mount RCDs for additional circuits. The latter may be useful when adding a circuit for radios in the "shack", or an outlet for an EV charger. If asking a landlord, the socket for a "vacuum cleaner" or "polisher" - too many believe Murdoch propaganda re fires or radiation, or some other nonsense. Kick the sparky a little extra for the 15 amp or greater capacity outlet and perhaps heavier wiring.
In industrial use these can hold terminal blocks, bases for plug-in relays, contactors, timers, indicators, power supplies, metering, motor starters, and PLCs (programmable logic controllers). Apart from terminals, each item is a 18 mm wide, or a multiple of this. There are also C and G profile, and miniature versions.
For worker safety a lot of factories, etc, are going to 24 volt control systems, usually with relays with 24 volt AC coils. Previously they used relays with 110, 240, or 400 volt AC coils.
These consist of a central pin, and an outer housing, connected to the coax shield.
The PL-259 is a popular plug which connects to a SO-239 socket. Actually, these codes related to specific versions, but generically it applies to all related units. These have a characteristic impedance of something like 30 ohms, so they cause reflections in the feedline. They are used at HF, and up to around 150 MHz, according to the examiner. However, they are used on US versions of some radios at 70 cm (US versions of the FT-857D, the European one used an N socket), and some Aussie UHF CBs. They get called "UHF" connectors, from the era when 70 or 80 MHz was termed UHF.
These are ⅝" (15.875 mm) in diameter with a 24 TPI thread. M connectors are visually similar, but with a 16 × 1 mm thread are incompatible.
Two gentlemen, Neill and Concelman, developed a series of constant impedance connectors which bear their initials.
The C-connector, alluded to in one of the spoilers, is a fairly large bayonet connector, more substantial than an N-connector, and which could easily handle a kilowatt. They are used in avionics (aircraft electronics and communications), and military systems.
The N is a threaded connector, available in 50 and 75 ohm versions. While they are advertised as "moisture resistant", like any coaxial termination, you still need to apply self-amalgamating (mastic) tape, then black electrical tape, then grey electrical tape, over these terminations if installed permanently. The grey looks like galvanising, and discourages birds. They are mechanically stable, and maintain their quoted impedance through the connection, so may be good up to 10 GHz. They also use a ⅝" 24 TPI thread.
BNC and TNC, bayonet and threaded connectors developed by the two blokes above, are medium sized connectors, with the threaded version being more mechanically stable, and therefore having a higher frequency rating. BNCs are popular on older HTs, test equipment, and in 75 Ω form, profesional video. The examiner sets the upper frequency limit for BNCs at 4 GHz.
The spoiler for the N appears to allude to the use of BNC connectors in computer networking, including ARCnet, and 1980s Ethernet. N plugs were also used in very early Ethernet, but these have a screw-on shell. BNCs were also used in 1990s "SDI" digital video in TV studios.
SMA is a smaller threaded connector, good for quite a few gigahertz. There are also even smaller connectors, of similar appearance, including the SMC connector.
Motorola / Vertex Standard use the "Mini-UHF" socket on some of their radios. These are a 50 Ω connector, ⅜" or 9.525 mm in diameter, with a toothed end which prevents rotation. The matching plug typically accepts RG-58 and similar cables. I am not sure if PG1607 is a manufacturer specific code. They were also used on the company's car and bag mobile telephones. Also from the era, the female FME is an 8 mm diameter connector able to pass through holes marginally larger than RG-58, or similarly sized "CELL-FOAM" cable. Assembled cables featuring this connector are available which can be used with an inter-series adaptor on the N, BNC, TNC, PL-259, Mini-UHF, etc on your mobile radio. NMO antenna bases using them are also available.
There are many push-on connectors from the SMA sized SMB and QMA, the smaller SSMB; and progressively tinier MC-Card, MCX, and MMCX, the latter group often used for current mobile 'phone cradles, and cellular modems, especially useful in rural and remote areas.
FAKRA is based on the SMB, and uses keyed and colour-coded shells. It is used in car entertainment and in-dash navigation systems, for things such as broadcast radio, GPS, and composite video from reversing cameras.
For confusion value (but not on the exam), there are also large "7-16 DIN" RF connectors, typically used with Heliax.
The screw-on F series is used on US broadcast receive antennas; and on cable-based and domestic satellite systems (globally), ditto a few DAB+ receivers. Belling-Lee push-on plugs are used in the PAL, now DVB-T, world. All are 75 Ω. If choosing wall plates for antenna connections, use F where possible over Belling-Lee.
The RCA Phono connector is a mid-1930s connector designed for occasional disconnection of audio signals in phonograph (record) players, primarily for use during servicing, including when a radio and record player was included in one piece of furniture. They are also used for interconnecting HiFi "components" - cassette recorders, CD players, MiniDisc recorders, and optionally, VCR or DVD audio; as well as for SPDIF consumer digital audio. They have a long pin carrying the signal, which connects before the shield, resulting in loud buzzes if plugged into powered systems. Professional versions have a retracting shield, which makes contact first, for when consumer gear is connected to professional systems. RCAs are however fairly mechanically stable, so better than 3.5 mm connectors.
They can be useful for DIY projects where room allows. In many cases they are mounted in a way in which the shield / body is connected to the case should this be metal, although insulated versions are also common.
They also support composite, component (RGB), and YCbCr video in consumer systems. Many affordable metal-shelled versions accommodate RG-59, good for video signals.
They are used for things like HF antenna inputs of receivers, and IF outputs on high-end radios. You could certainly build a radio which presented a DC voltage to a moving coil meter via such a connector, or via a 3.5 mm one, as on the FT-857D, to meter signal strength, modulation, FM frequency error, SWR, etc. I have seen this connector used as the RF socket on a budget 27 MHz CB.
There are some crazy "audiophile" versions, using strange materials, including timber, and supposedly, "carbon nanotubes", along all sorts of psycho-babble claims re the metals and insulation, sorry "dielectric" used. Weird, as in JD Vance grade weird.
Serious audio gear uses jack plugs / phone plugs / 6.5 mm plugs / ¼" plugs (actually 6.35 mm) for unbalanced audio, or Cannon / XLR ones for balanced audio. There is however the potentially confusing 3 way 6.5 mm version, where the tip and sleeve can be left and right unbalanced, send and return unbalanced for connecting effects units, or balanced mono audio.
Professional audio, especially at microphone level, uses XLR Connectors, from the X series invented by James H. Cannon; they are Latching, and used Resilient neoprene rubber around the female contacts. Technically, the other brands are copies of either the XL, or XLP, with hard Plastic. Belt-pack wireless microphones often use Switchcraft Tini-QG connectors, cloned by others as the "Mini-XLR". Both carry balanced audio, and shield.
Light Emitting Diodes emit light when the diode junction is forward biased, such that current flows forward through them, in the direction of the arrowhead. They can be a single indicator, or grouped to form 7-segment or other displays. Newer high current version are useful for illumination.
7-segment LEDs digits are typically sold as common anode or common cathode, and may include a decimal point (DP). Multi-digit displays use multiplexing, so positive supply is applied to each digit in turn, and the cathodes for each number to be displayed are pulled to ground momentarily, this repeated many times per second. Given 2&sup7; = 127 there are a range of letters which can be displayed, including A, b, C, d, E, and F, allowing hexadecimal values to be displayed, such as 1Ed39C, the HTML colour code for the text. 14 or 16 segment displays allow the alphabet, and some symbols, to be displayed.
Liquid Crystal Displays (LCDs) use a material which changes polarisation when a very small current is applied to them. Most often they are configured so that the background is light grey, and the numerals, etc, are dark grey. They require external illumination to be visible, or may include a backlight. Illumination can be filament lamp, LEDs, or the very nice looking electroluminescent material.
While NOT an answer to the exam question, leaving radios with LCDs exposed to extreme temperatures on vehicle dashboards is less than ideal for their reliability and durability. It can also cause short term darkening. One way LCDs are connected to the PCB is via the infamous Zebra strip, a rubber strip containing thin alternating layers of light insulating silicone, and dark carbon loaded conductive silicone, placed so they conduct signals up from the board to the display. These can shrink very slightly, and lead to non-operational lines or segments late in the life of a product.
1980s HF rigs, especially from Kenwood, use Vacuum Fluorescent Display, typically with a cyan or greenish colour. These used heated cathode wires, and an anode at 50 volts.
Several technologies allow dot-matrix displays, often with 16 characters × 2 lines, the characters being 7 ×5 pixels. The LCD on the FT-857D is 133×33 dots, allowing a smaller frequency display plus other info, or larger numerals, or the display of menus.
Small displays using OLEDs (organic LEDs) can be used with processor based projects to display menus or parameters. Organic means that they are made from hydrocarbon (hydrogen-carbon) compounds, rather than semiconductors. Early ones had a limited lifespan, hence the distractor below.
Custom VFDs and LCDs can include icons and small text. On multimeters these may include: m, μ, V, A, DC, AC, k, M, Ω, Hz, HV, HOLD, °C. They also support bargraphs, etc. Symbols on VFDs can be red, yellow, or other colours.
Big dollar rigs use various coloured LCD technologies, often TFT, potentially with touch-screens. The Icom IC-R9000 had an amber Cathode Ray Tube.
Nixie tubes contained neon, and (typically) digits from 0 to 9 cut from thin plate. They were used in things like frequency counters, and 1970s butchers' scales. They are now only used in low volume production or kit clocks for those who seek an anachronistic or "steam-punk" aesthetic. Even cooler is the Dekatron, which is both a display and counter / memory in one valve. I remember that my school had a Geiger which included several of these.
At least one mobile radio had a composite video output to place the frequency / channel display onto a larger screen, and a few big dollar ones VGA or HDMI outputs - potentially handy for public demonstrations, and ham classes, especially if used with a projector.
For confusion value, the rules for Hams in VK are / were in a document called the LCD - Licence Condition Determination.
These are actual questions from the General exam pool.
G6B01
What determines the performance of a ferrite core at different frequencies?
A. Its conductivity
B. Its thickness
C. The composition, or "mix," of materials used
D. The ratio of outer diameter to inner diameter
This is the "mix", meaning the combination of materials used, answer C.
The typo is permitted to be edited out, if the question is used in an exam.
G6B02
What is meant by the term MMIC?
A. Multi-Mode Integrated Circuit
B. Monolithic Microwave Integrated Circuit
C. Metal Monolayer Integrated Circuit
D. Mode Modulated Integrated Circuit
Monolithic Microwave Integrated Circuit, answer B.
G6B03
Which of the following is an advantage of CMOS integrated circuits compared to TTL integrated circuits?
A. Low power consumption
B. High power handling capability
C. Better suited for RF amplification
D. Better suited for power supply regulation
CMOS ICs have low power consumption, and are suitable for battery powered devices, answer A.
Another upside is that they often don't need to be supplied via a regulator, and many will operate over the 10 to 6 volt range of a discharging 9 volt battery, or the 10 to 15 volts found in an automotive system.
G6B04
What is a typical upper frequency limit for low SWR operation of 50-ohm BNC connectors?
A. 50 MHz
B. 500 MHz
C. 4 GHz
D. 40 GHz
The upper limit for BNC connectors is around 4 GHz, answer C.
G6B05
What is an advantage of using a ferrite core toroidal inductor?
A. Large values of inductance may be obtained
B. The magnetic properties of the core may be optimized for a specific range of frequencies
C. Most of the magnetic field is contained in the core
D. All these choices are correct
The nature of ferrite materials, and of toroidal windings, makes all of these things true. It is answer D.
Toroidal windings tend to contain the magnetic energy within the core, and allow large values of inductance to be achieved. Toroidal transformers were popular in "linear" power supplies within larger audio amplifiers, as they helped to avoid hum being induced into low level audio signals. In this case a laminated steel core was used.
G6B06
What kind of device is an integrated circuit operational amplifier?
A. Digital
B. MMIC
C. Programmable Logic
D. Analog
An operational amplifier (op-amp) IC is an analogue device, answer D.
G6B07
Which of the following describes a type N connector?
A. A moisture-resistant RF connector useful to 10 GHz
B. A small bayonet connector used for data circuits
C. A low noise figure VHF connector
D. A nickel plated version of the PL-259
N connectors are fairly large, and are claimed to be moisture resistant. They work at up to 10 GHz, so answer A.
All connections should be properly waterproofed if outside for any significant period of time.
G6B08
How is an LED biased when emitting light?
A. In the tunnel-effect region
B. At the Zener voltage
C. Reverse biased
D. Forward biased
The emission of light requires forward current flow, meaning it must be forward biased, answer D.
G6B09 re LCDs has been removed.
G6B10
How does a ferrite bead or core reduce common-mode RF current on the shield of a coaxial cable?
A. By creating an impedance in the current's path
B. It converts common-mode current to differential mode current
C. By creating an out-of-phase current to cancel the common-mode current
D. Ferrites expel magnetic fields
They cause an inductive reactance to RF current flow, aka an impedance, answer A.
G6B11
What is an SMA connector?
A. A type-S to type-M adaptor
B. A small threaded connector suitable for signals up to several GHz
C. A connector designed for serial multiple access signals
D. A type of push-on connector intended for high voltage applications
These are quite small, and are threaded. They are also good for (at least) several GHz, answer B.
I have used these at 100 watts on 6 metres, but wouldn't push the power beyond that.
G6B12
Which of these connector types is commonly used for low frequency or dc signal connections to a transceiver?
A. PL-259
B. BNC
C. RCA Phono
D. Type N
The examiner is looking for the RCA (phono) connector, which can be used for audio, IF, and DC signals answer C.
Below the line for things removed from recent exams, but potentially interesting.
The Octal socket consists of a fairly large 8 pin valve (tube) base used as the socket. The plug fits this. The plug features a central plastic post, keyed to ensure correct orientation. They are used in things like connecting control signals to external RF amplifiers and other accessories from the Kenwood TS-820S discussed previously. They can handle large currents and voltages, but care needs to be taken the ensure the user is not exposed to dangerous voltages, as the contacts may be nearly flush with the face of the socket, which is not an issue within equipment, but is on a back panel.
They are also used for industrial relays and timers, to at least 415 volts. There is an 11 pin version, allowing change-over control of three phases (or other lines), using 3PDT contacts (9 pins for the contacts, plus 2 for the coil). Often these bases are designed to fit DIN rails.
The top image and a section of this Wikipedia article refer to the Octal socket. See: Wikipedia: Tube Socket. The Polish page Wikipedia (Polish): Cokół (lampy), meaning "Plinth", has many illustrations. Clicking an image often provides the English name as the file name.
Examples of valves / tubes using this base include the 6L6, 6L6GC, 6V6, EL-34, KT-66, KT-88; and using an anode cap at the top, the famous 807 (also slang for an intoxicating beverage in a single-serve sized bottle). These were often used in the output stage of amateur HF transmitters, as well as in audio equipment, and beam deflection in TVs.
Plastic relay bases may not handle the temperatures generated by valves, and dedicated valve ones, potentially ceramic, should be used.
"Modern" signal level valves often use smaller 7 or 9 pin sockets. The 6AU6 (EF94) and 12AU7 (ECC82) are examples.
In days of old, memory used to be accessed sequentially, by clocking data around a chain of registers. A "shift register", mentioned in a question, is a device, which when clocked moves data through the memory array.
The more modern form is "Random Access Memory", RAM, where any byte or word can be read rapidly. There are also two types, Read-Write Memory, RWM; and Read Only Memory, ROM, physically made in the photo-masking process at the chip factory.
RWM become known as RAM, in contrast to the ROM which contained the BASIC, or boot-strap software for CP/M systems. This is despite most ROM technically also being randomly accessible. RAM is normally "dynamic", and needs to be refreshed periodically. However, a few computers, such as the ROM BASIC MicroBee used static RAM with a NiCad battery, so your programme was preserved even if power failed, or you turned the power off. In PCs the ROM is called the BIOS, held in flash memory, so it can be updated.
Variations on ROM are PROM, programmable ROM (write once, read many times); EPROM, erasable PROM, erased by exposing the device to intense UV light via the quartz window on the top, which should be covered by a sticker (ideally with the version number written on it); and the latest EEPROM or E-squared-PROM (E²PROM), electrically erasable programmable read only memory.
An interesting feature of the MicroBee was that you could purchase a EPROMs containing a word processor; or a terminal programme, useful for connecting to packet radio equipment; which meant it was not necessary to load these from tape; and it may well have run more quickly, without using the BASIC interpreter.
In microcontrollers, in addition to the processor, there may be some "bootstrap" ROM; plus EEPROM or PROM, depending of whether you wish to update the programme or have it fixed; and RAM. EEPROM versions are often used by hobbyists, and for development work.
Non-volatile means that memory is preserved, even when power is removed. These are a real improvement over radios which required lithium coin-cells (often soldered in), or strings of expensive silver-oxide cells, etc, to maintain their memories.
Since we are here: 8 bits = 1 byte. 4 bits is a nibble, enough for a single digit number. A word is a single character the width of the system's data bus, typically 8, 16, 32, or 64 bits. Z80 systems such as the MicroBee or VZ-200 / VZ-300 used 8 bit words. 1 kilobyte is 210 or 1024 bytes; 1 MB is 1024 kB, and 1 GB is 1024 MB. Given this is 1,073,741,824 bytes, you can see shonky marketers would use traditional 109 giga to call a true 128 GB rotating drive a 137 GB drive, and rename the 128 version as 128 GiB. A true megabyte is 220 bytes, a true gigabyte 230.
Kilobits per second (kbps or kb/s) and megabits (Mb/s) are used for data transfer rates. Given things such as stop and check bits, it takes around 10 bits to transfer a byte, plus potentially packet headers, etc.
Something like a BASIC program to calculate the dimensions of various full-sized loop antennas might occupy a few kB, or less if written in Assembler.
If you skipped ahead, you should return to Electrical Principles 1 now.
On to: Circuits 1 - Power supplies and Schematics
You can find links to lots more on the Learning Material page.
Written by Julian Sortland, VK2YJS & AG6LE, October 2024.
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