Description:

This listing if for a used Hopper Game Cartridge for an Acorn Electron computer.

Good condition with labels on the front and top. (See photos)

The Tree Of Knowledge is designed to introduce children to using computers for the storage of information and its retrieval. For simplicity the program is restricted to simple objects within a specified subject. For example, if the subject were 'plants' the objects could be 'a dandelion' and 'an apple tree'.

New objects are introduced to the program by means of a simple guessing game, using questions which can be answered with 'yes' or 'no'. With each new object the user supplies a question which will distinguish that object from those already known about. Because at every stage the answer to a question can be 'yes' or 'no' the database can be represented as a 'tree'. The question at every node has two branches, one for a 'yes' answer and one for a 'no' answer, and the objects are at the tips of the branches.

No documentation included.

We can ship Worldwide.

If delivery to your country is not shown please contact us for the price.

For other vintage / Retro computers, computing parts and accessories, see our other items!

International orders

International orders (including to the European Union) may also be subject to import duties, and other local taxes and charges, which the buyer will be responsible for. We will always ensure items have a correctly filled Customs document.

We follow ebay guidelines and only send to a verified PayPal address unless by prior arrangement.
UK delivery: Light Items are normally sent by Royal Mail untracked post, heavier items are sent by 3-5day courier.
Non UK delivery is normally sent by untracked Airmail (2-3 weeks Europe, 3-6 weeks for most of the rest of the world).
Next day delivery in the UK and express delivery to the rest of the world can be arranged.

Payment

Cheques payable to "Fourth Dimension" please.
Bank transfers to Sort Code: 20-20-62 Account no.: 70677213 Acc. Name: Fourth Dimension
International bank account no.: IBAN GB26BARC 202062 7067721
SWIFT BIC: BARCGB22 n.b. If your Bank requires an 11 character SWIFT BIC, use BARCGB22XXX instead.

About Us

four-d-pi-shop is the ebay arm of CJE Micro‘s & 4D, who have the world's widest range of Raspberry Pi/RISC OS & Acorn accessories including many from third parties, most of which are famously normally 'In Stock'. Established in 1981, we have always specialised in hobbyist computing and have gained a reputation for a broad knowledge with high quality pre- and post-sales service.
CJE & 4D have, over the years, developed many of our own products for Acorn/RISC OS & Raspberry Pi computers. From the first ever 3rd party accessory for BBC Micro Model B (cassette leads) to the first ever 3rd party hardware for the Raspberry Pi Model B (Real Time Clock Module).
We are continuing to develop new products and expect to make a number of significant launches during the next year. Fourth Dimension (4D) is a sister business to CJE Micro's, having been a sibling since 1998.

Contact Us

The Shop

Our showroom and sales area is normally open from: Monday to Friday 9am - 5.30pm
To find our shop you can view our address in the "Business Seller Information" below.