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Joined: Jun 2005
Of the 14 possible peripheral flags, only flags 3 and 4 were not assigned to any released HP product. Here's a table from my working notes:
flag test
num opcode device mnem expansion
---- ------ ------ ----- ------------------------
0 3ac 82143A ?PBSY Printer BuSY
1 32c 82104A ?CRDR CaRD Reader
2 22c 82153A ?WNDB WaND Byte available
3 02c none ?PF 3
4 06c none ?PF 4
5 0ac 82242A ?EDAV Emitter Diode AVailable
6 16c 82160A ?IFCR InterFace Clear Received
7 2ac 82160A ?SRQR Service ReQuest Received
8 12c 82160A ?FRAV FRame AVailable
9 26c 82160A ?FRNS Frame Received Not as Sent
10 0ec 82160A ?ORAV Output Register AVailable
11 1ac 82182A ?TFAIL
12 36c 82182A ?ALM ALarM
13 2ec all ?SERV SERVice
I would strongly advise against using more than one flag for a new device. These flags are only intended to be used to quickly identify conditions that awaken a 41 from light sleep, so it is reasonable for a device to use one of them, but to further distinguish which condition of that device resulted in the wakeup, data should be read from the device.
HP chose to use up five of the scarce flags for HP-IL, but that probably seemed like a reasonable use of the scarce resource because it was expected that almost all further peripherals would use HP-IL rather than dedicated interface modules.