All 3800 or 3900 printers

The following illustration shows the contents of register 0, which includes the GCM ID, the CAT ID, and the reason code.

Unused (bits 0-7), GCM ID (bits 8-15), CAT ID (bits 16-23) and reason code (bits 24-31)

Table 1 shows the hexadecimal reason codes for the IBM® 3800 Model 1 and the other 3800 or 3900 models in compatibility mode. These reason codes, returned in register 0, are in addition to return codes X'04', X'08', X'0C', and X'4C' returned in register 15.

Table 1. Reason Codes for IBM 3800 or 3900 Printers (for Return Codes 04, 08, 0C, 4C)
GCM ID (Byte 1)	CAT ID (Byte 2)	Reason Code (Byte 3)	Meaning
00	01-04	04	Character arrangement table module/record.
00	00	08	Copy modification module/record.
00	00	0C	Starting copy number.
01-04	01-04	10	Graphic character modification module/record.
00	00	14	Forms overlay sequence control record.
00	00	18	Library character set.
00	00	1C	Writable character generation module (WCGM).
00	00	20	Forms control buffer module.