Theory of Operation
The ZT 8825 is a state-of-the-art STD bus compatible memory board
that accommodates most popular byte-wide memory chips. It is
electrically, physically, and logically compatible with the STD bus as
defined by the STD-80 Series Bus Specification. In addition, the
CMOS version ZT 88CT25 is TTL compatible. Unless specifically
noted, all references to ZT 8825 in this manual refer also to
ZT 88CT25.
There are eight memory chip sockets on the ZT 8825. These sockets
are divided into two rows of four. Each row can be independently
configured for memory chip type (for example, EPROM, EEPROM,
static RAM).
The ZT 8825 uses the STD-80 Series 20-bit memory address
protocol. It can also accommodate 24-bit addressing. The user sees
the board as many separate 16 Kbyte memory boards. In addition to
implementing the normal 1 Mbyte STD-80 Series address space, the
ZT 8825 allows access to Extended Memory address space up to 16
Mbytes. Also implemented are the Lotus-Intel-Microsoft Expanded
Memory Specification (EMS), Versions 3.2 and 4.0, and the AST
Enhanced Expanded Memory Specification (EEMS), Version 3.2,
allowing access to up to 2 Mbytes of memory on the board. Multiple
boards may be used to achieve up to 32 Mbytes of memory.
3-3
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com