Phil I forgot to add in the previous post that the only difference I was aware of between System/4 I/O and IBM I/O was possibly to be expected. In "simulating/emulating" the "direct access", I made sure that the IBM DASD mimicked the System/4 DASD. I can't remember exactly why but it may have been related to the program needing to know how many blocks would fit on each track. I was reminded to mention this by seeing yet more posts in the current "MB to Cyl Conversion" thread.
In looking into this issue/problem I discovered that the algorithm which determined the remaining track capacity given a new block of a certain size - with or without a key and, if a key was needed, of what size - was different for the System/4 DASD models and the current IBM DASD. It wasn't just a matter of changing the constants for the different types of DASD. Thus I was obliged to code the whole "direct access" support modules at the CCW level and introduce a "channel-end appendage" routine, It's a good job I had an understanding manager, sadly only recently no longer with us, who let me indulge myself to this extent (sic). Although it appeared to work correctly in testing with trivial exercises, I don't believe my care with the "direct access" logic was ever tested by a real world program during one of my demonstrations of the SIM4 package. Chris Mason ----- Original Message ----- From: "Phil Payne" <[EMAIL PROTECTED]> Newsgroups: bit.listserv.ibm-main To: <[email protected]> Sent: Friday, 15 December, 2006 4:48 PM Subject: IBM sues maker of Intel-based Mainframe clones > > ... > > System 4 J, if memory serves. The I/O was different - CCW formats and such. > > ... > -- > Phil Payne > http://www.isham-research.co.uk > +44 7833 654 800 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
