Sinclair ZX81 Operation & User’s Manual

INFORMATION FOR PROGRAMMERS The interface lives on I/O port 7 which is fully decoded. Bits 15...13 of the address bus are latched when port 7 is accessed and then used as a channel number in order to perform different tasks. Therefore the only valid IO instructions for accessing the port are: out (c),a in a,(C) The B register should hold the channel number in its top 3 bits. Here is an example which sends the value 23 to command channel 5: ld bc,%1010000000000111 ld a,23 out (c),a So what can usefully be done? Many of the interface’s functions requi ...

WHAT DO I NEED The ZXpand comes ready to plug into your Sinclair ZX81 home computer, switch on and go. However, you will need a standard SD card to be able to store files. If you wish to insert the interface into a case, then it is designed to fit within a Memotech memory expansion case with some modification to allow access to the card slot - see section on fitting the ZXpand in a case below. GETTING STARTED Format an SD card - you can use any of the standard FAT format types: 12, 16 and 32 are supported. Once formatted, you can save some ZX81 programs to it. These ...

CONFIG CONFIG "x" CONFIG "x=y" (Press shift-G in K mode – replaces ‘LLIST’ command) The CONFIG command is the main method of communicating with and configuring the ZXpand interface. As the working of some programs and commands is affected by how the interface is set up, this will be dealt with first. Parameters to the command and their effects are: “V” Displays the interface's version string. “R=nnnnn“ Sets RAMTOP to the specified value and executes NEW. “M=L” Sets the 'Low' or 8-40K RAM mapping. See notes below. “M=H” Sets the 'High' or 16-48K ...

TABLE OF CONTENTS TABLE OF CONTENTS ....................................................................................................... 2 NOTICE ................................................................................................................................ 3 OVERVIEW .......................................................................................................................... 4 COMPATIBILITY .................................................................................................................. 4 WHAT DO I NEED ............. ...