PROHVK38@TREARN.BITNET (orhan) (03/24/90)
Does anybody know IPL RECORD format ?
This record is first record in any sub system device.
thanx in advanceJIM@AUVM.BITNET (Jim McIntosh) (03/26/90)
In article <ASM370%90032315491404@EB0UB011>, orhan <PROHVK38@TREARN.BITNET> says: > Does anybody know IPL RECORD format ? Sure. Refer to pages 4-35 through 4-37 in the System/370 Principles of Operation (GA22-7000), or equivelent pages in the XA or ESA POOs, for a good overview of what happens during an IPL. Basically, a read with a length of 24 is issued. An initial PSW (0-7) and two additional CCWs (8-15 and 16-23) are read to address 0. This initial read is done as if the command chain bit is on, and control is chained to the CCW at address 8. Usually this first CCW would read in some more CCWs and the second CCW would TIC to them. When the initial I/O operation completes, the PSW at address 0 is loaded and you're on your way. (Note that this initial PSW can be part of the IPL record, or it can be placed at address 0 by a subsequent CCW.) So the IPL record format is: +--------+--------+--------+-----------... | PSW | CCW1 | CCW2 | Ignored +--------+--------+--------+-----------... 0 8 16 24 ------- Jim McIntosh (JIM@AUVM) The American University Washington DC 20016 USA
alawrenc @UCBVAX.BERKELEY.EDU (a.lawrence) (03/27/90)
PROHVK38@TREARN.BITNET (orhan): > Does anybody know IPL RECORD format ? > This record is first record in any sub system device. The standard IPL record on any System\370 device is 24 bytes. It consists of 2 CCW's (channel command words) followed by a PSW (Program Status Word). The IPL function issues a read (X'02') command to the specified device into location zero (sorry I don't remember the length), a TIC (transfer in channel) to location zero to execute the CCW's just read. When the channel program terminates, the PSW is loaded from location X'000010'. For a complete description of the process, refer to the "Princples of Operation" manual for your particular computer. --- On a clear disk you can seek forever. ------------------------------------------------------------------------- Andrew Lawrence | alawrenc@sobmips.sobeco.UUCP Informaticien Conseil | {attcan,mcgill-vision}!sobeco!sobmips!alawrenc 3462 Jeanne-Mance, #1 | Montreal, Que CANADA | Voice (514) 281-5196