ZX80

The Sinclair ZX80 is a home computer by the British company Sinclair from the year 1980. He is the predecessor of the Sinclair ZX81. The hardware of the successor produced in far greater quantities is similar but more highly integrated and therefore more cost effective. The housing of the ZX80 is white and slightly bulkier than that of the black ZX81. The housing of the ZX80 was designed by industrial designer Rick Dickinson. The Z80 CPU is clocked at 3.25 MHz, which corresponds to the then state of the art.

The ZX80 is connected via the built-in modulator with a cable to the antenna terminal of a TV. There text is displayed with 32 columns and 24 rows.

The character set is not ASCII compliant and contains non-alphanumeric also the key words of BASIC. Most of the BASIC commands can be entered with a single keystroke. Only a few functions such as PEEK () and CHR $ () must be entered letter by letter. Thus, the programs require very little space in a relatively small memory of the ZX80.

Between the ZX80 and its successor the ZX81 there are some differences:

  • The read only memory (ROM ) of the ZX80 is only 4 KB of the ZX81 at least 8 KB.
  • The smaller ROM only allowed for a smaller instruction set of Sinclair BASIC than on the ZX81.
  • Unlike the ZX81 ZX80 which can not count on floating point numbers. The integers of the ZX80, values ​​between -32768 and 32767 accept (16 bit).
  • The ZX80 has 21 chips (discrete TTL modules ), while the ZX81 comes with five, later versions contain only four chips.
  • Since neither the ZX80 still ZX81 are equipped with a separate video controller, the main processor is also responsible for the screen display. While the ZX80 keyboard input or the execution of basic commands and utilities still cause correspondingly long dropouts when the screen display, the ZX81 is located by default in a SLOW mode, in which the computation takes place only during the blanking interval.

Otherwise, the ZX80 and ZX81 are technically much the same, so that it is possible for more details refer to the ZX80 ZX81 product. The ZX80 could be upgraded with the 8 -KB ROM of the ZX81 and a matching new keyboard sheet, whereby the differences disappeared with respect to language scope and floating point numbers. This upgrade was officially provided by Sinclair and the ZX81 ROM had been specifically programmed so that it worked in the ZX80. However, such an upgraded ZX80 knows the SLOW mode is not capable of displaying a stable image ( with reduced processing speed ). For the experienced hobbyist but these can be retrofitted with little effort and the installation of some other chips, so that the ZX80 can be upgraded to a full ZX81. However, an original ZX80 due to the rarity today significantly higher collector's value as an upgraded.

Byte Read-only memory
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