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***JulianW*** · 01-09-2007, 06:37 AM

The Sinclair ZX 81 was the successor of the ZX 80, and can be regarded as an evolution of it.

The ZX80 could not handle floating point numbers or cassette data files, but the ZX-81 could. The ZX-80 had 4k ROM : the ZX-81 had 8K ROM with 30 additional functions and some instructions to drive the printer. Thanks to a higher level of integrations (the total number of chips in the basic system was 4, against the ZX80's 21), the ZX-81 cost £30 less than the ZX-80. The plastic case was also different. Whereas the ZX-80 looked cheap in it lightweight white case, the ZX-81 was beautifully designed in its black ABS plastic case.

The keyboard was still formed by an underprinted plastic, but this one was made of non-reflective material. Even with this slight improvement it was quite horrible to use, that's why a lot of additional keyboards appeared quickly on the market. Some of the keys sported up to 5 functions, right in the Sinclair tradition, accessible through the "GRAPHICS", "SHIFT" and "FUNCTION" keys.

Here are the functions added over the ZX-80 : ASN, ACS, ATN COS, EXP, INKEY$, PI, SGN, SIN SQR, INT, LEN, LN, TAN, VAL, <=, >=, < >, COPY, DIM A$, FAST, FOR ... TO ... STEP, LLIST, LLIST n, LPRINT, PAUSE, PLOT, PRINT AT, PRINT TAB, SCROLL, SLOW, UNPLOT. Some are quite useful and make you wonder how it was possible to make anything on the ZX-80 !? However, one function disappeared: TL$ which was used to return a string minus its first character.

The ZX-81 could be operated in two modes, SLOW and FAST. The FAST mode which was the only mode available on the ZX-80, only refreshed the display when the system had completed computing, resulting in a painful screen flicker! It was a useful mode when you had to do a lot of calculation without the need to see what's going on all the time on the screen. The SLOW mode, which was indeed quite slooooowwww, behaved like all other computers did, refreshing the screen all the time.

The ZX81 contained only four main chips : the ROM, Z80A CPU, 1K RAM and the Ferranti custom-made chip! It is as simple as that. The machine was assembled by Timex Corporation in their Scottish plant.

This computer was a very great success in Europe in the beginning of the 80's. It was very cheap and a lot of people who now are working on modern PCs or Macs, made their first move on a ZX 81 even though its performance was actually poor!

A very great range of peripherals were developed for this computer, among them : 3.5" floppy disk units, keyboards, high resolution graphic cards, RS232 or Centronics interfaces, RAM expansions, etc... In fact, it was possible to make a pretty good computer from the ZX 81!

It was followed by the ZX-Spectrum and was also sold as the Times Sinclair 1000 in the USA.

***JulianW*** · 01-10-2007, 06:06 AM

Public can purchase $100 laptop

The laptop will be delivered to countries in the summer

The backers of the One Laptop Per Child project plan to release the machine on general sale next year.
But customers will have to buy two laptops at once - with the second going to the developing world.
Five million of the laptops will be delivered to developing nations this summer, in one of the most ambitious educational exercises ever undertaken.
Michalis Bletsas, chief connectivity officer for the project, said they were working with eBay to sell the machine.
"If we started selling the laptop now, we would do very good business," Mr Bletsas, speaking at the Consumer Electronics Show, told BBC News.
"But our focus right now is on the launch in the developing world."

Durable
The laptop has been developed to be as low cost, durable and simple to use as possible.
The eventual aim is to sell the machine to developing countries for $100 but the current cost of the machine is about $150.
The first countries to sign up to buying the machine, which is officially dubbed XO, include Brazil, Argentina, Uruguay, Nigeria, Libya, Pakistan and Thailand.
The XO's software has been designed to work specifically in an educational context. It has built-in wireless networking and video conferencing so that groups of children can work together.
The project is also working to ensure that children using the laptop around the world can be in contact.
"I'd like to make sure that kids all around the world start to communicate. It will be a very interesting experiment to see what will happen when we deploy a million laptops in Brazil and a million laptops in Namibia."

'Glue'
The OLPC project is working with Google who will act as "the glue to bind all these kids together".

The machine is close to a final design

Google will also help the children publish their work on the internet so that the world can observe the "fruits of their labour", said Mr Bletsas.
He said that the plan was to put the machine on sale to the general public "sometime next year".
"How to do that efficiently without adding to the cost is difficult," he said.
"We're discussing it with our partner eBay. We need to minimise supply chain cost , which is pretty high in the western world."

Philanthropic organisation
Mr Bletsas said that a philanthropic organisation would be formed to organise the orders and delivery of the laptops.
"It's much more difficult to do this than making the laptop," he said.
The aim is to connect the buyer of the laptop with the child in the developing world who receives the machine.
"The will get the e-mail address of the kid in the developing world that they have, in effect, sponsored."
Mr Bletsas was speaking amidst the festival of consumerism taking place on the show floor of CES.
He said he hoped that the laptop project would help children enrich their lives to the extent that one day they could become consumers of the types of technologies on display in Las Vegas.

'Castigated'
But he castigated the industry for being unambitious in its plan to "connect the next billion people".
"They should look to connect the next five and a half billion.
"The way to do it is not to try and deploy tried and trusted technology but to try and develop technology specifically targeted to the developing world."
He said that OLPC was ensuring that laptops were being deployed to areas where there was internet access.
"We are trying to help the governments - that ranges from donating resources, to making sure that we work with them and that they don't consider the laptop as something that can work in a disconnected environment.
"It's vitally important that children are connected. My ambition is that we will get them connect to a vast amount of information that is unavailable to them.
"It will stimulate their interest in looking further - not waiting for some teacher or an adult."

***papa-bear*** · 01-10-2007, 10:58 AM

Quote:

But customers will have to buy two laptops at once - with the second going to the developing world.

What a good idea. Now to prove the second one goes to a child in a developing country.

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