IBM 6824, 2289 manual Address hex, Description, Bits, Byte pointer, User Guide

Address (hex)	Description	Bits	Byte pointer
00C4	Channel 5, memory address register	00 – 15	Yes
00C6	Channel 5, transfer count register	00 – 15	Yes
00C8	Channel 6, memory address register	00 – 15	Yes
00CA	Channel 6, transfer count register	00 – 15	Yes
00CC	Channel 7, memory address register	00 – 15	Yes
00CE	Channel 7, transfer count register	00 – 15	Yes
00D0	Channels 4–7, read status/write command register	00 – 07
00D2	Channels 4–7, write request register	00 – 02
00D4	Channels 4–7, write single mask register bit	00 – 02
00D6	Channels 4–7, mode register (write)	00 – 07
00D8	Channels 4–7, clear byte pointer (write)	N/A
00DA	Channels 4–7, master clear (write)/temp (read)	00 – 07
00DC	Channels 4–7, clear mask register (write)	00 – 03
00DE	Channels 4–7, write all mask register bits	00 – 03
00DF	Channels 5–7, 8- or 16-bit mode select	00 – 07

40User Guide