Picture the keypad of a telephone and calculator side by side. Can you see the subtle difference between the two without resorting to your smartphone? Don’t worry if you can’t recall the design. Most of us are so used to accepting the common interfaces that we tend to overlook the calculator’s inverted key sequence. A calculator has the 7–8–9 buttons at the top whereas a phone uses the 1–2–3 format.


Typewriters, Cash Registers, and Calculators

Looking at the key arrangement, I was curious to learn when the system of using keys was introduced in the history of machines. The keyboard came about sometime between the first and second industrial revolutions (from 1820 to 1920). Some inventors had already begun experimenting with machines similar to pianos in the late 18th century.

However, it wasn’t until 1844 that a Frenchman by the name of Jean-Baptiste Schwilguć came up with the first working prototype of a key-driven calculator machine. This machine used the first numerical keyboard with a single row of keys that increased from 1 to 9 (Dalakov, 2018).

In all fairness, though, we have to mention two predecessors that could claim they invented the key-based interface. In 1834, Luigi Torchi reportedly showed a prototype of a wooden calculator, with a design similar to the typewriter. In 1822, author James White’s New Century of Inventions showed a key-based device with nine numeric keys. Neither one stood up to the test of time, nor no proof was given that they weren’t just fantasy (Durant, 2011).

Next
Hello World

ClaPat at 1:51 pm, October 11, 2018 -

This is a comment test for this post added by our website admin

ClaPat at 1:51 pm, October 11, 2018 -

This is a comment reply test for this post added by our website admin

nuckemamn at 5:32 pm, May 7, 2021 -

immuniodo at 3:36 pm, May 27, 2021 -

Rubenquova at 4:13 pm, June 13, 2021 -

Где смотреть Евро-2020? По каким каналам можно посмотреть матчи Евро-2021?
Полная информация на сайте https://cerrajerosrivasvaciamadrid.site/2021/17-smotret-evro-2021-za-1-dollar/?utm_content=noutbuki&gclid=CjwKCAjwqvyFBhB7EiwAER786Z0LHMq3_FTF8J2ndP743o1bRxyhRktJBgyopErI8UHLnc0hWg6fnxoCpDcQAvD_BwE

Простейшие варианты где можно смотреть Евро-2020 бесплатно или за 1 доллар в месяц в качестве HD.

immuniodo at 4:27 pm, June 14, 2021 -

cialis online price at 11:42 pm, June 17, 2021 -

cialis online price

cialis online price

free viagra at 11:09 am, June 18, 2021 -

free viagra

free viagra

what is tadalafil at 2:27 pm, June 19, 2021 -

what is tadalafil

what is tadalafil

cialis paypal uk at 5:15 pm, June 19, 2021 -

cialis paypal uk

cialis paypal uk

sildenafil best price at 9:16 pm, June 19, 2021 -

sildenafil best price

sildenafil best price

online viagra purchase at 12:31 am, June 20, 2021 -

online viagra purchase

online viagra purchase

gabapentin at 2:08 pm, June 20, 2021 -

gabapentin

gabapentin

online tadalafil 20mg at 4:15 pm, June 20, 2021 -

online tadalafil 20mg

online tadalafil 20mg

purchase vardenafil online at 7:42 pm, June 20, 2021 -

purchase vardenafil online

purchase vardenafil online

sildenafil walmart at 8:14 pm, June 21, 2021 -

sildenafil walmart

sildenafil walmart

norvasc drug class at 11:58 pm, June 21, 2021 -

norvasc drug class

norvasc drug class

atorvastatin dose at 2:57 am, June 22, 2021 -

atorvastatin dose

atorvastatin dose

meloxicam dose at 10:53 pm, June 22, 2021 -

meloxicam dose

meloxicam dose

what is metoprolol at 2:14 am, June 23, 2021 -

what is metoprolol

what is metoprolol

losartan dosage at 4:06 am, June 23, 2021 -

losartan dosage

losartan dosage

viagra boys at 10:27 am, June 23, 2021 -

viagra boys

viagra boys

tadalafil tadalafromcanada at 1:07 pm, June 23, 2021 -

tadalafil tadalafromcanada

tadalafil tadalafromcanada

levitra drug prices at 4:23 pm, June 23, 2021 -

levitra drug prices

levitra drug prices

cymbalta 30mg at 6:45 pm, June 23, 2021 -

cymbalta 30mg

cymbalta 30mg

prednisone depression at 10:52 pm, June 23, 2021 -

prednisone depression

prednisone depression

elavil at 3:09 am, June 24, 2021 -

elavil

elavil

warnings for cymbalta at 4:15 am, June 24, 2021 -

warnings for cymbalta

warnings for cymbalta

warnings for hydrochlorothiazide at 8:17 am, June 24, 2021 -

warnings for hydrochlorothiazide

warnings for hydrochlorothiazide

dangers of taking metformin at 12:25 pm, June 24, 2021 -

dangers of taking metformin

dangers of taking metformin

mirtazapine for sleep in elderly at 3:42 pm, June 24, 2021 -

mirtazapine for sleep in elderly

mirtazapine for sleep in elderly

bupropion 300 mg at 1:57 am, June 25, 2021 -

bupropion 300 mg

bupropion 300 mg

buspar medication at 2:58 am, June 25, 2021 -

buspar medication

buspar medication

celexa vs lexapro at 5:10 am, June 25, 2021 -

celexa vs lexapro

celexa vs lexapro

muscle relaxer tizanidine at 6:57 am, June 25, 2021 -

muscle relaxer tizanidine

muscle relaxer tizanidine

wellbutrin xl at 7:18 am, June 25, 2021 -

wellbutrin xl

wellbutrin xl

voltaren arthritis at 7:02 am, June 26, 2021 -

voltaren arthritis

voltaren arthritis

clonidine patch at 2:51 pm, June 26, 2021 -

clonidine patch

clonidine patch

finasteride 5mg side effects at 8:32 pm, June 26, 2021 -

finasteride 5mg side effects

finasteride 5mg side effects

coreg side effects at 10:43 pm, June 26, 2021 -

coreg side effects

coreg side effects

flagyl antibiotic at 11:54 pm, June 26, 2021 -

flagyl antibiotic

flagyl antibiotic

cialis and alcohol at 12:47 pm, June 28, 2021 -

cialis and alcohol

cialis and alcohol

order viagra at 2:52 pm, June 28, 2021 -

order viagra

order viagra

cialis alternative at 6:44 pm, June 28, 2021 -

cialis alternative

cialis alternative

viagra on steroids at 9:10 pm, June 28, 2021 -

viagra on steroids

viagra on steroids

levitra price in singapore at 10:38 pm, June 28, 2021 -

levitra price in singapore

levitra price in singapore

acyclovir ointment at 1:03 pm, July 2, 2021 -

acyclovir ointment

acyclovir ointment

generic amoxicillin cost at 3:31 pm, July 2, 2021 -

generic amoxicillin cost

generic amoxicillin cost

warnings for donepezil at 3:53 pm, July 2, 2021 -

warnings for donepezil

warnings for donepezil

side effects of azithromycin at 8:04 pm, July 2, 2021 -

side effects of azithromycin

side effects of azithromycin

side effects for cefdinir at 3:55 am, July 3, 2021 -

side effects for cefdinir

side effects for cefdinir

keflex 500mg at 6:11 am, July 3, 2021 -

keflex 500mg

keflex 500mg

what is clindamycin for at 6:38 am, July 3, 2021 -

what is clindamycin for

what is clindamycin for

erythromycin 250 mg coupon at 7:53 am, July 3, 2021 -

erythromycin 250 mg coupon

erythromycin 250 mg coupon

azithromycin 500 mg tablet at 9:31 am, July 3, 2021 -

azithromycin 500 mg tablet

azithromycin 500 mg tablet

cialis fast delivery usa at 2:51 pm, July 5, 2021 -

cialis fast delivery usa

cialis fast delivery usa

cialis free sample at 6:17 pm, July 5, 2021 -

cialis free sample

cialis free sample

cialis for bph at 9:25 pm, July 5, 2021 -

cialis for bph

cialis for bph

cialis 20 at 1:00 am, July 6, 2021 -

cialis 20

cialis 20

viagra free samples at 4:25 am, July 6, 2021 -

viagra free samples

viagra free samples

immuniodo at 12:28 am, July 7, 2021 -

generic cialis buy at 2:02 pm, July 7, 2021 -

generic cialis buy

generic cialis buy

purchase levitra at 2:42 pm, July 7, 2021 -

purchase levitra

purchase levitra

rx pharmacy viagra at 7:22 pm, July 7, 2021 -

rx pharmacy viagra

rx pharmacy viagra

cost for cialis 20mg at 8:29 pm, July 10, 2021 -

cost for cialis 20mg

cost for cialis 20mg

cialis dosage strengths at 12:12 am, July 11, 2021 -

cialis dosage strengths

cialis dosage strengths

viagra dosing at 3:14 am, July 11, 2021 -

viagra dosing

viagra dosing

super viagra at 6:36 am, July 11, 2021 -

super viagra

super viagra

female viagra review at 10:24 am, July 12, 2021 -

female viagra review

female viagra review

rush limbaugh viagra at 8:46 am, July 13, 2021 -

rush limbaugh viagra

rush limbaugh viagra

otc viagra alternative at 11:54 am, July 13, 2021 -

otc viagra alternative

otc viagra alternative

viagra cost at 2:32 pm, July 13, 2021 -

viagra cost

viagra cost

canada viagra at 5:56 pm, July 13, 2021 -

canada viagra

canada viagra

amlodipine 5 mg tablet at 4:16 am, July 15, 2021 -

amlodipine 5 mg tablet

amlodipine 5 mg tablet

cialis 20mg prices at 5:11 am, July 15, 2021 -

cialis 20mg prices

cialis 20mg prices

levitra 10mg tablets at 9:58 am, July 15, 2021 -

levitra 10mg tablets

levitra 10mg tablets

metformin 500 mg tablets at 10:52 am, July 15, 2021 -

metformin 500 mg tablets

metformin 500 mg tablets

cialis black 800mg at 4:11 pm, July 15, 2021 -

cialis black 800mg

cialis black 800mg

doxycycline at 6:37 pm, July 18, 2021 -

doxycycline

doxycycline

furosemide generic at 8:40 pm, July 18, 2021 -

furosemide generic

furosemide generic

xenical pills for sale at 1:00 am, July 19, 2021 -

xenical pills for sale

xenical pills for sale

dapoxetine brand name india at 2:41 am, July 19, 2021 -

dapoxetine brand name india

dapoxetine brand name india

cost of finasteride at 4:25 am, July 19, 2021 -

cost of finasteride

cost of finasteride

bimatoprost mechanism of action at 11:35 pm, July 19, 2021 -

bimatoprost mechanism of action

bimatoprost mechanism of action

generic clomid at walmart at 12:01 am, July 20, 2021 -

generic clomid at walmart

generic clomid at walmart

fluconazole dosage adults at 2:00 am, July 20, 2021 -

fluconazole dosage adults

fluconazole dosage adults

domperidone maleate medication at 5:13 am, July 20, 2021 -

domperidone maleate medication

domperidone maleate medication

tamoxifen manufacturer at 5:00 pm, July 21, 2021 -

tamoxifen manufacturer

tamoxifen manufacturer

Amydoone at 5:40 pm, July 21, 2021 -

prednisolone acetate 5mg at 6:13 pm, July 21, 2021 -

prednisolone acetate 5mg

prednisolone acetate 5mg

Kiadoone at 6:53 pm, July 21, 2021 -

naltrexone for fibromyalgia at 8:16 pm, July 21, 2021 -

naltrexone for fibromyalgia

naltrexone for fibromyalgia

valtrex generic drug at 9:54 pm, July 21, 2021 -

valtrex generic drug

valtrex generic drug

Lisadoone at 1:55 am, July 22, 2021 -

zanaflex high reddit at 3:44 am, July 22, 2021 -

zanaflex high reddit

zanaflex high reddit

Amydoone at 9:02 am, July 22, 2021 -

Lisadoone at 9:54 am, July 23, 2021 -

cialis 10 mg at 4:41 pm, July 23, 2021 -

cialis 10 mg

cialis 10 mg

purchase cialis online at 6:59 pm, July 23, 2021 -

purchase cialis online

purchase cialis online

Amydoone at 4:49 am, July 24, 2021 -

Kiadoone at 5:34 am, July 24, 2021 -

Dendoone at 10:36 pm, July 24, 2021 -

Pauldoone at 1:10 am, July 25, 2021 -

Dendoone at 8:51 am, July 25, 2021 -

Lisadoone at 11:30 am, July 25, 2021 -

Markdoone at 3:06 pm, July 25, 2021 -

Jasondoone at 4:40 pm, July 25, 2021 -

Kiadoone at 7:23 pm, July 25, 2021 -

Alandoone at 11:38 pm, July 25, 2021 -

Lisadoone at 12:22 am, July 26, 2021 -

Dendoone at 12:59 am, July 26, 2021 -

ciprofloxacin warfarin interaction at 3:38 am, July 26, 2021 -

ciprofloxacin warfarin interaction

ciprofloxacin warfarin interaction

Judydoone at 3:44 am, July 26, 2021 -

Jasondoone at 6:51 am, July 26, 2021 -

tadalafil citrate bodybuilding at 8:06 am, July 26, 2021 -

tadalafil citrate bodybuilding

tadalafil citrate bodybuilding

40 mg cialis at 11:11 am, July 26, 2021 -

40 mg cialis

40 mg cialis

Eyedoone at 2:30 pm, July 26, 2021 -

Alandoone at 4:28 pm, July 26, 2021 -

cialis cost 20mg at 6:55 pm, July 26, 2021 -

cialis cost 20mg

cialis cost 20mg

Judydoone at 8:01 pm, July 26, 2021 -

Marydoone at 10:30 pm, July 26, 2021 -

viagra samples at 10:35 pm, July 26, 2021 -

viagra samples

viagra samples

Carldoone at 10:56 pm, July 26, 2021 -

sildenafil capsule at 11:27 pm, July 26, 2021 -

sildenafil capsule

sildenafil capsule

viagra interactions at 3:01 am, July 27, 2021 -

viagra interactions

viagra interactions

Amydoone at 4:29 am, July 27, 2021 -

Alandoone at 4:33 am, July 27, 2021 -

Amydoone at 3:02 pm, July 27, 2021 -

Pauldoone at 10:18 pm, July 27, 2021 -

Judydoone at 10:41 pm, July 27, 2021 -

Carldoone at 10:46 pm, July 27, 2021 -

Marydoone at 12:11 am, July 28, 2021 -

immuniodo at 1:38 am, July 28, 2021 -

Markdoone at 3:42 am, July 28, 2021 -

Lisadoone at 4:50 am, July 28, 2021 -

Amydoone at 7:29 am, July 28, 2021 -

Kiadoone at 10:44 am, July 28, 2021 -

Amydoone at 7:19 pm, July 28, 2021 -

Dendoone at 8:08 pm, July 28, 2021 -

Markdoone at 9:20 pm, July 28, 2021 -

Eyedoone at 11:19 pm, July 28, 2021 -

Marydoone at 12:35 am, July 29, 2021 -

Carldoone at 5:06 am, July 29, 2021 -

Pauldoone at 5:49 am, July 29, 2021 -

Eyedoone at 7:17 am, July 29, 2021 -

Lisadoone at 8:34 am, July 29, 2021 -

Jasondoone at 9:48 am, July 29, 2021 -

Pauldoone at 5:35 pm, July 29, 2021 -

Judydoone at 5:40 pm, July 29, 2021 -

Alandoone at 6:13 pm, July 29, 2021 -

Carldoone at 10:14 pm, July 29, 2021 -

Dendoone at 11:36 pm, July 29, 2021 -

Amydoone at 2:21 am, July 30, 2021 -

Alandoone at 6:53 am, July 30, 2021 -

Eyedoone at 11:37 am, July 30, 2021 -

Lisadoone at 9:36 pm, July 30, 2021 -

Kiadoone at 12:36 am, July 31, 2021 -

Marydoone at 1:10 am, July 31, 2021 -

Kiadoone at 3:56 am, July 31, 2021 -

Jasondoone at 6:49 am, July 31, 2021 -

Amydoone at 11:27 am, July 31, 2021 -

Marydoone at 4:02 pm, July 31, 2021 -

Judydoone at 4:44 am, August 1, 2021 -

Carldoone at 5:55 am, August 1, 2021 -

Markdoone at 6:35 am, August 1, 2021 -

Dendoone at 9:38 am, August 1, 2021 -

Carldoone at 4:19 pm, August 1, 2021 -

Alandoone at 5:19 pm, August 1, 2021 -

Carldoone at 10:13 pm, August 1, 2021 -

Judydoone at 10:06 am, August 2, 2021 -

Alandoone at 11:17 am, August 2, 2021 -

Dendoone at 2:38 pm, August 2, 2021 -

Eyedoone at 6:04 pm, August 2, 2021 -

Pauldoone at 7:05 pm, August 2, 2021 -

Lisadoone at 10:17 pm, August 2, 2021 -

Markdoone at 10:56 pm, August 2, 2021 -

Kiadoone at 2:41 am, August 3, 2021 -

Whazbh at 5:47 am, August 3, 2021 -

cialis online cheap – cialis 100 how does it work 20mg tadalafil

Amydoone at 4:17 pm, August 3, 2021 -

Jasondoone at 4:21 pm, August 3, 2021 -

Jasondoone at 4:38 pm, August 3, 2021 -