8
© Sealevel Systems, Inc.
4021 Manual | SL9154 11/2021
Card Setup, Continued
Interface Selection
RS-232
A DIP-shunt placed at E9 selects RS-232 (V.24).
V.35
A DIP-shunt placed at E10 selects V.35.
DMA Options
Headers E1 and E7 select the
D
irect
M
emory
A
ccess (DMA) mode of operation for the
ACB 56.
Channel A
of the SCC can operate in either half duplex or full duplex DMA mode. Full duplex DMA can transmit and
receive data simultaneously. Half-duplex DMA can transmit or receive data, but not in both directions
simultaneously.
If DMA is not used, remove all of the jumpers on E1 and E7. Refer to Page 6 for the most
common DMA settings.
Header E1
1
DACK 1 Or 3 Acknowledge For Two Channel Mode
2
Two Channel A/B Mode A3B1
3
Two Channel A/B Mode A1B3
4
On = Ch. A Only / Off = Ch. B Only
5
DACK 3 DMA Acknowledge Channel 3
6
DACK 1 DMA Acknowledge Channel 1
Figure 4 - Header E1
1
23456