Already since the old DOS time (now probably unknown to the latest levers) a request for miniaturization had produced the first results.
Somebody may still remember the Quaderno of Olivetti which prefigured the actual low cost models' current size ( but the cost was still too high because its price in Italy that was about Lit.1.400.000)

Dimensioni: 21cm x 15cm x 4.3cm (formato A5) --- Peso circa 1.1 Kg Display: 7' (640 x 400 a 16 livelli grigio) Tastiera: 93/94 tasti + Tastierino Num. Processore NEC V30HL funzionante a 4, 8, 16 MHz (selezionabile dal'utenet) Memoria: 1 MB(640 KB base + 360 KB expanded) HDD: all' origine con un 20MB + (opzionale)PCMCIA type 1 SRAM cards NiCad battery pack o 6 pile formato AA alkaline per approssimativamente 8 ore di durata. Dotazione: Microfono / presa cuffia / RS232 seriale / parallela & floppy disk(opzionale) Registratore con Voice Manager

Personally, I had chosen, even if i liked the Quaderno, an Elox MiniPC (also sold as Memorex SuperMini) that had a display surely smaller but could mount memories PMCIA up to 2Mb and, unlike the miniPC of that time, Quaderrno included, give me doors, serial, parallel etc in standard forma instead of the prpprietary type and, very important a price of about Lit.980.000.

Dimensioni: 23cm x 11cm x 2.9cm --- Peso circa 0.580 Kg Display: CGA (80 x 25 Colonne/righe) Tastiera: qwerty (80% dimens.standard) Processore Intel 8088 a 4.77 o (turbo) 7.16 mhz Memoria: ROM 640 KB / RAM 640 KB HDD: non disponibile + Memory Card fino a 2MB + (opzionale)Floppy Dish drive esterno 4 pile formato AA alkaline per approssimativamente 20 ore di durata+backup al litio Dotazione: speaker / RS232 seriale / parallela /porta I/O

From the 2 models shown above we can note two lines of development.
If the Quaderno had been produced by a Japanese industry, perhaps the category Low Cost PC would be born first. In fact, after a brief success, to have further development were models that could offer smaller sizes and greater portability.
I refer to some models like the Psion MX 5 that rather than pursue a miniaturization of the PC offered a type of evolved agendas that with the adding of Writing System Graffity and a different form factory were the winning product of Palm.

Dimensioni: 17cm x 9cm x 2.3cm --- Peso circa 0.354 Kg Display: touchscreen 640 x 240 a 16 livelli grigio Tastiera: Qwerty Processore ARM710T 36 MHz Memoria: Ram 16 MB / Rom 8 Mb HDD: non disponibile + CompactFlash Card - type II 2 Alkaline - AA per circa 30 ore autonomia Dotazione: Microfono / Altoparlante / RS232 seriale / Irda

Later, the MiniPCI could have had another outcome with the first versions of WinCE, that instead disappointed expectations. .

Many of these Pdas running under Microsoft O.S. WinCE (vers.1 or 2) were de facto, HPC. (Handle PC). For example the Casio A20 powered by 2 AA batteries and with a reduced keyboard that was my first mini PC to program directly on WinCE and for WinCe (Thanks to NSBasicCE).

Dimensioni: 18,5cm x 9,4cm x 2,4cm --- Peso circa 0.430 Kg Display: touchscreen LCD 640 x 240 pixels - 4 grayscales Tastiera: qwerty (dimensione 65% dello standard) Processore: Hitachi SH3 a 80 MHz Memoria: Ram 8 MB / Rom 8 MB HDD: non disponibile + CF Type I e PC Card Type II 2x AA autonomia fino a 25 hours + CR2032 batteria backup rimovibile Dotazione: Microfono / altoparlante / RS232 seriale / Irda

Later I used a model NEC 770 product from a Brand that has continued to sell (not for Europe) models of HPC running under WinCE PRO
also when. from Microsoft, was privileged a form of PDA without keyboard (abandoning the development of O.S dedicated to the hpc )
to be a better competitor of  the Palm handheld.  

Dimensioni: 24.5cm x 13,1cm x 2,9cm --- Peso circa 0.770 Kg Display: Touchscreen 8.1' 65536 colori 640 x 240 + video out VGA Tastiera: Qwerty Processore: 64bit NEC VR4121 a 131 MHz Memoria: Ram 24 MB / Rom 32 MB HDD: non disponibile + PCMCIA I e II, CF I e II. Batteria Litio 1000 mAh Dotazione: Microfono/Altoparlante/cuffia/RS232 seriale/USB 1.1/Irda/ Modem V90+FaxModem Registratore con Voice Manager

Thus while calling its products Pocket PC, Microsoft failed the opportunity to develop a miniPCI. Intention whose existence is betrayed by the fact that only Microsoft HPC format had , in addition to the common office suite, also Access Program and others usually absent in the PDA-palm size models.
This gives again a wrong start to the miniaturization of the PC so that the only models produced were some type of subnotebook, or attempts to reduce a PC in the size of a PDA.

Two examples may be representative of those: the FlyBook

Dimensioni: 23.5cm x 15.5cm x 3.1cm --- Peso circa 1,250 Kg Display: touchscreen 8.9" wide-view 16:9 1024x600 color 32-bit + video out SXGA Tastiera: Qwerty 80-key standard keyboard Processore: Transmeta Crusoe TM-5800, a 1GHz Memoria: Ram 512MB HDD: 40 GB + PCMCIA Type-I/II Batteria ricaricabile 3-cell Li-Ion Dotazione: Micro/speaker/BT/RJ-45/Modem 56k/WiFi/GPRS Triband/2 USB 2.0/2 firewire

for the subnotebook type. Or the model OQO, representing the Pda PC

Dimensioni: 14.2cm x 8.4cm x 2.6cm --- Peso circa 0.454 Kg Display: 127mm diagonale a colori 800x480 base + zoom + video esterno Tastiera: qwerty 80-keys scorrevole Processore 1.6GHz VIA C7M ULV Memoria: 1 GB(640 KB base + 360 KB expanded) HDD: 120GB (anche 60GB o 80GB) oppure 32GB o 64GB SSD Batteria removibile li-ion 4500mAh o 9000mAh per circa 3 o 6 ore Dotazione: Micro/Speaker/presa cuffia/wifi/BT/Ethernet/GSM-UMTS/1 USB 2/Docking

The latter, in truth, has undergone various changes and long waiting time before to appear on the market but has also been able to exploit    
the officialization of this type of devices conferred to this items by the Microsoft Origami operaration (that they launched to regulate the Ultra 
Mobile PC category). 
Category yet indistinct in the wishes of many users who continued to see, incorrectly, in a evolved pda a miniPCI.

The operation Origami has never taken off, even if it was supported by manufacturers like Samsung, Asus and many others, for its
specifications , unrealistic and / or too anticipatory, which firstly created no practical items, lacking of a good authonomy and with high
prices. After the models that are cited in the page above, other UMPC models have been presented but, in my opinion, the improvements
were not such as to create a real demand for UMPC models..

But Microsoft had placed the first stone of a building that others would then developed