DMA Channel Allocation
VL-486-4 Reference Manual
Configuration – 39
DMA Channel Allocation
The VL-486-4 has two DMA controllers which provide a total of eight DMA channels (four 8-bit
channels and four 16-bit channels.) One 8-bit or 16-bit channel (jumper selectable) is available
for general purpose use through a front-plane DMA connector (J6). The remaining channels are
accessible only by software.
Table 18: DMA Channel Allocation.
DMA
Channel
Data
Width
Channel
Allocation
0
8 Bit
Not Used
1
8 Bit
Not Used
2
8 Bit
On-Card Floppy
3
8 Bit
General DMA via Front Plane
Request:
J6, Pin 2 (FPRQ*)
Acknowledge: J6, Pin 4 (FPAK*)
(V3=OUT)
4
16 Bit
Not Used
5
16 Bit
Not Used
6
16 Bit
Not Used
7
16 Bit
General DMA via Front Plane
Request:
J6, Pin 2 (FPRQ*)
Acknowledge: J6, Pin 4 (FPAK*)
(V3=IN)