Editing Psion Organiser (section)

==Organiser I==
{{Infobox information appliance
| name = Psion Organiser I
| title = 
| aka = 
| logo = 
| image = Psion Organiser 1.jpg
| caption = Psion Organiser I
| developer = [[Psion (company)|Psion PLC]]
| manufacturer = Psion PLC
| family = Psion Organiser
| type = [[Pocket computer]]
| generation = 1
| release date = {{Start date and age|1984}}<!-- If known, add |mm|dd -->
| retail availability = 
| lifespan = 
| price = [[Pound_sterling|£]]99 [[Pound sterling|GBP]], [[Canadian dollar|C$]]199 
| discontinued = {{End date and age|1986}}<!-- If known, add |mm|dd -->
| units sold = 
| units shipped = 
| media = 
| os = no
| power = 
| soc = 
| cpu = [[8-bit computing|8-bit]] [[Hitachi]] 6301
| memory = 2 KB
| storage = 
| memory card = 2 Datapaks
| display = [[Liquid crystal display|Liquid crystal]] 1 line
| graphics = 
| sound = 
| input = [[Keypad]] 6×6
| controllers = 
| connectivity = 
| currentfw = 
| platform = 
| service = 
| dimensions = 142 × 78 × 29.3 mm
| weight = 225 grams
| topgame = 
| compatibility= 
| predecessor = 
| successor = Psion Organiser II
| related = 
| marketing_target = 
| website = <!-- {{URL|example.org}} -->
| language = English
}}
Launched in 1984,<ref name="pountain198411">{{cite news |last=Pountain |first=Dick |date=November 1984 |url=https://archive.org/stream/byte-magazine-1984-11/1984_11_BYTE_09-12_New_Chips#page/n411/mode/2up |title=A Plethora of Portables |work=Byte |access-date=23 October 2013 |pages=413}}</ref>  the Psion Organiser was the "world's first practical pocket computer".<ref>[https://web.archive.org/web/20180329173907/http://www.bioeddie.co.uk/models/psion-organiser-1.htm Psion Organiser One]. bioeddie.co.uk</ref> Based on an [[8-bit]] Hitachi 6301-family processor, running at 0.9&nbsp;MHz, with 4&nbsp;[[kilobyte|KB]] of [[read-only memory]] (ROM) and 2&nbsp;KB of [[static RAM]] and has a one-row monochrome [[liquid crystal display]] (LCD) screen. The size with the case closed is 142 × 78 × 29.3&nbsp;mm, and the mass is 225&nbsp;grams.

A ''[[Byte (magazine)|Byte]]'' reviewer described the Organiser's software as a "clever design ... for fast and foolproof use". He approved of the consistent user interface across applications and reported that without documentation he was able to learn how to do everything except program in 15 minutes.{{r|pountain198411}} The machine provided a simple [[flat-file database]], [[calculator]] and clock, and had no [[operating system]] (OS). The Organiser I supported removable storage [[write once read many]] (write-once) devices, which used ''erasable programmable read-only memory'' [[EPROM]] storage. The device can host two of these, named Datapaks (stylized as DATAPAK, or simply PAK), to which it can write data, but which must be removed from the device and erased by exposure to [[ultraviolet]] light before they can be re-used. As Psion had patented the use of EPROMS as a storage device, it was impossible for other device makers to copy this unusual approach to mobile storage.

Software supplied on Datapak included a crude [[programming language]] named POPL, in which end-users could write their own programs.{{r|pountain198411}} Software Datapaks titled Science, Maths and Finance contained the POPL programming language editor, [[Interpreter (computing)|interpreter]] and [[runtime system]] and extended the built-in calculator by adding named functions. These Datapaks also contained different sets of [[application software]] written in the POPL language.

A far more sophisticated programming tool was later made available with the implementation of the [[Forth (programming language)|Forth]] language, but was available to registered professional developers rather than end users. The Psion Forth Development System for the Organiser I was a powerful set of IBM PC-based [[Cross compiler|cross-development]] tools for producing Forth application software, including a Forth [[compiler]]. The Forth system on the Organiser I had a compiler to [[intermediate code]], interpreter and runtime, and had several unusual design features one being that it could interpret – that is, read and execute – Forth intermediate code directly in place on a Datapak, rather than needing to copy it into precious RAM first, despite the Datapaks not being [[execute in place|execute-in-place]] memory-mapped.

Software developed by Psion as part of the Organiser I project, and application software after its launch, was written in 6301 [[assembly language]], in POPL, and in other custom-designed languages. Assembly language development at Psion was carried out using cross-development tools, including a [[cross assembler]] and linker, all of which ran on a [[Digital Equipment Corporation]] (DEC) [[VAX]].

Application developers writing in 6301 assembly struggled with the small amount of RAM (2&nbsp;KB) and the lack of an operating system. Another difficulty for developers was with the performance limits of the earliest Datapaks, which used a serial-access internal architecture, instead of [[random access]]. Retrieving, for example, byte 2000 from a Datapak meant issuing successive hardware commands to either step from the current read position one address place at time until position 2000 was reached or, in the worst case, resetting the read position to zero and then issuing a step-forward command 2000 times.{{Citation needed|date=November 2012}}

The Hitachi 6301 processor is an enhanced development based on the [[Motorola 6800|Motorola 6801]] implemented in ''complementary metal–oxide–semiconductor'' ([[CMOS]]), with several extra [[Instruction set architecture|instructions]], various hardware [[system on a chip]] (SoC) facilities on-chip, power management and support for a sleep state. The particular variant chosen also had 4&nbsp;KB of masked ROM on-chip, so an external ROM was unneeded on the board.

Having fully [[Static random-access memory|static RAM]] and a processor which [[clock signal|clock]] could be frozen without losing state meant very long battery life, measured in weeks or even months. Minimal power use was aided by the processor being frozen whenever there was no work to do, plus a deeper [[sleep mode]], which turned off the [[Electronic visual display|display]].

The machine lacked a full independently battery-backed, date-time real-time hardware clock, instead it had a simple hardware [[Counter (digital)|counter]]. While the machine was sleeping, the counter counted 1,024 seconds and then woke the machine very briefly, so that software could add 1,024 seconds to a record of the time held in RAM. This meant that when sleeping the machine woke very fleetingly every 17 minutes 4 seconds.

The original 1984 price was £99&nbsp;[[Pound sterling|GBP]] or $199&nbsp;[[Canadian dollar|CAD]] and included one Datapak and one software Datapak, the ''Utility'' pack. This latter adds scientific and trigonometric functions to the otherwise basic calculator routines.