Sinclair XZ81 - Miniature
SIZE 36*35*8 mm
The ZX81 was launched on 5th March 1981 by Clive Sinclair as the successor to the ZX80, with a larger memory and improved mathematical functions. It was available ready-built (£69.95) or in kit form (£49.95).
In the advertising of the ZX81, Sinclair boasted that the higher specification and lower price were a result of design. The ZX80 had reduced the chips in a working computer from around 40, to 21. The ZX81 then reduced that number to 4. The ZX81 was based around the Z-80A CPU which ran at 3.5MHz. It came with 1K of RAM, and 8K of ROM providing a simple BASIC interpreter. The other chip was an uncommitted logic array (ULA) chip from Ferranti which Sinclair advertised as their unique, custom-built, "master chip" which replaced 18 ZX80 chips.
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.