BASICARE TURNS THE MICRO INSIDE OUT
BASICARE seems to be intent on revolutionising the world of microcomputing by providing all the facilities of a computer except the CPU and the language outside the micro. The system contains RAM and can be extended to Centronics printers, character generators, battery-backed RAM, RS232 with no worry about where to fit them in the 64K of the memory map of the ZX-81.
When fully-expanded the Basicare system could have 112 peripherals, divided into SLOTs on each page of the memory map. Sixteen pages of 32K worth of dynamic memory, 512k of memory for use by Basic or machine code, four 8K areas of DATA plus four 8K areas of TOOLKIT routines - ROM/RAM or battery-backed RAM. Total memory size of the system is 576KB. Since they take up most of the expense of any system, Basicare has made them compatible with most computers by linking them via a 64-way edge connector. The computer is connected to that bus via a PERSONA module, which fits into the computer memory map. That way the modules can remain the same: it is only the position on the memory map which changes.
The basic system must consist of a computer - at present the only PERSONAs available are for the ZX-81 and the Spectrum - and the PERSONA for that computer.
Having established the system for accessing all those extra boxes, you are still limited to 64K of memory map - 8K or 16K ROM. 8K for SLOT and PATH areas, and the rest can be RAM unless you buy a MINIMAP module to switch the pages in the system. That would seem essential, otherwise there are many other cheaper systems which stay within 64K.
Extra memory may be added in 16K or 64K dynamic portions or 2K chips of static memory. Dynamic memory can be used only in the 16K-32K and 48K-64K regions of the memory map. The RAM pack containing static chips may have a USER-FRONT option fitted to allow you a programmable character set.
The SLOT area in the memory map - 44K-48K - is used to store all the input/output devices such as Centronics printer module - Pericon c - and the two types of 24-line input/ output ports available - Pericon a and b. The SLOT is also used to access the MINIMAP by POKEs to change the pages. Another 4K area, called PATH, is not specified in the documentation and presumably will act like the BBC computer TUBE interface to connect to other micros.
The file area - dynamic RAM - can be used to hold segments of a program like subroutines. Those subroutine pages can be called by a Basic POKE to change from one routine to another.
Basicare Microsystem Ltd is at 12 Ricketts Street, London, SW6 5EL, tel: 01-385 2135.
Basicare expansion system