EPROM Services

Allows up to 8K of EPROM or RAM in 2K blocks to be added in the 8-16K ZX81 memory map. Supplied with EPROM I which contains 40 toolkit type routines, including scroll up/down/left/right, free memory, renumber program length.

Port-mapped expansion board using the Intel 8255 PIA chip. Provides two Centronics ports, one for output to a printer, the other for data input. A 32 byte PROM overrides ROM printer routines and directs the commands to driver software. Fully supports BASIC LPRINT, LLIST and COPY statements. Driver software loads above RAMTOP but can be

Peripheral enabling alternate character sets to be used and printed either from EPROM or user-defined character sets in RAM. 4K of EPROM is supplied containing 4 character sets and routines to print, copy, lprint and switch between character sets. A further 2 x 2K of RAM or EPROM can be added.

32 line I/O board. Ports mapped to 4 absolute locations. Port A has 8 LED indicators. Port B has 8 outputs. Splits into 2 ways each so one instruction can be used to switch between two peripherals. Port C is uncommitted. A status indicator gives a 16 LED indicator of the state of Port B.