Epson Apex 286/12, User Manual, Page: 117 / 128

Direct Memory Access
Eight DMA channels are supported by the system. Two Intel 8237-5
DMA controller chips (four channels in each chip) are used to provide
eight DMA channels. The DMA channels are assigned as follows.
CTR 1 CTR 2
C H 0 Spare C H 4 Cascade for CTRL 1
CH 1 SDLC
C H 5 Spare
C H 2 Diskette C H 6
Spare
CH 3 Spare C H 7 Spare
Table 6-9: DMA Channels
DMA Channel
Channels 0 through 3 are contained in DMA controller 1. Transfers of
8-bit data, 8-bit I/O adapters and 8-bit or 16-bit system memory are
supported by these channels. Each of these channels will transfer in
64KB blocks throughout the 16-megabyte system address space.
Channels 4 through 7 are contained in DMA controller 2. To cascade
channels 0 through 3 to the microprocessor, use channel 4. Transfers
of 16-bit data between 16-bit adapters and 16-bit system memory are
supported by channels 5, 6 and 7. DMA channels 5 through 7 will
transfer data in 128KB blocks throughout the 16-megabyte system
address space. These channels will not transfer data on odd-byte
boundaries.
Chapter 6: Appendix 21