Zilog Z80230 - Manual (Page 260)

SCC/ESCC
User Manual
UM010903-0515 Application Notes
253
Push button switches are provided for Reset and Non-Maskable Interrupt (NMI). A method to 
generate an NMI, in response to a start bit received from the user’s PC or terminal, is also pro-
vided. The first transmitted Start bit on the RS-232. Console connector J1, after a Reset, also pro-
duces an NMI. This feature can be used to find which serial controller channel is connected to the
Console 
connector.
Address Map
EPROM is located at the highest addresses, and its size is programmable in the 80186 CPU for the
UCS output. The addresses of the Datacom controllers are programmed in the 80186 for the
PCS6-PCS0 outputs, as a block of 128x7=896 Bytes starting at a 1 KB boundary. The block can be
in 
I/O space or in a part of memory space that is not used for SRAM or EPROM. The starting 1 KB
boundary is called Physical Block Address (PBA) in the following sections. RAM extends
upwards from address 0.
The address map using 128K x 8 SRAMS and 64K x 8 EPROMS are listed in Table .
Suggested Address Map
EPROM
Two 28-pin EPROM sockets are provided. Both sockets must be populated to handle the 80186’s
16-bit instruction fetches. Jumper header J18 allows the sockets to be compatible with 2764s,
27128s, 27256s, or 27512s. Jumper J18 is jumpered at the factory to match the EPROMs pro-
vided. For 27512s only, jumper J18-J2 to J18-J3 and leave J18-J1 open. For 2764s, 27128s, or
27256s, jumper J18-2 to J18-1 and leave J18-3 open.
Function Address
RAM
00000-BFFFF
(E)SCC
D8000, 2, 4, 6, or
D8000-D803E
(even
address only)
ISCC
D8080-D80FE
(even
address only)
(M)USC
D8100-D81FF
IUSC
D8200-D837F
ISCC-IUSC-
(M)USC Reset
DB000-DB7FF
(if enabled)
27512 EPROM
E0000-FFFFF