Zilog Z16C35 Manuel d'utilisateur télécharger pdf (Page 215)

Application Note

The Zilog Datacom Family with the 80186 CPU

9-5

The three LSBs of the above MMCS values are 111 so that

the longest possible Reset pulse is generated when any of

the locations in the indicated range are accessed.

Note that if this feature is not needed, it can be disabled by

simply not programming the MMCS register.

Interrupt Daisy Chain (Priority) Order

Jumper block J25 selects whether the (E)SCC device is at

the start or the end of the interrupt daisy chain.

This variability is provided in part because early versions

of the 85230 ESCC had trouble passing an interrupt

acknowledge down the daisy chain if it occurred in

response to a lower-priority device’s request just as the

ESCC was starting to make its own request. Current

85230’s don’t have the problem.

Table 6. Address Ranges for Reset

RAM Size MMCS value

Address Range for which ISCC,

IUSC, and (M)USC are Reset:

32K x 8 3BFF 3B000-3B7FF

128K x 8 DBFF DB000-DB7FF

To make the interrupt priority be: Jumper J25 as follows:

(E)SCC highest, IUSC, ISCC, (M)USC lowest J25-J2 to J25-J3, J25-J4 to J25-J5 (J25-J1, J25X open)

IUSC highest, ISCC, MUSC, (E)SCC lowest J25-J1 to J25-J2, J25-J to J25-J4 (J25-5J, J25X open)

IUSC highest, ISCC, USC, (E)SCC lowest J25X to J25-J2, J25-J3 to J25-J4 (J25-J1, J25-J5 open)

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Zilog Z16C35 Manuel d'utilisateur Page 215