Note 3830 was the dasd string controller for 3330 volumes https://www.garlic.com/~lynn/2007d.html
floppy disk was originally developed for loading microcode into the 3830 disk controller ... and was also used for loading microcode into many of the 370 mainframe machines. this typically happened automatically at power-up ... however there has been recent subthread here on the "IPL" button on 360/370 front consoles ... "initial program load" ... which was software (boot) function. However 370s also had "IMPL" button ... initial microcode program load ... if there was some service update which included replacing the microprogram floppy disk ... then the microcode could be reloaded (w/o a power cycle). 3081 had service processor and a 3310/piccolo, FBA (fixed block architecture) "hard disk" containing microcode for the 3081 processor ... and some processor functions could involve "paging" microcode from the 3310. this is different than an instruction, dynamically modifying some (frequently immediately) following instruction, in the instruction stream. a lot of 360 (software) code made use of this feature to achieve real-storage compactness (compared to paging which also is oriented towards real-storage compactness). However, it was something of a performance penalty as processors started attempting to squeeze instruction latency ... doing instruction decode and setup overlapped with execution ... there had to be constant checking if some previous instruction had modified a following instruction that had already been fetched and decoded. No details in 6th edition November 1976 of 3830/3330 manual https://bitsavers.org/pdf/ibm/3830/GA26-1592-5_Reference_Manual_for_IBM_3830_Storage_Control_Model_1_and_IBM_3330_Disk_Storage_Nov76.pdf On Thu, Jul 11, 2024 at 11:00 AM Radoslaw Skorupka <[email protected]> wrote: > > I just found information in some book that IBM mainframes used 12 inch > floppy diskettes. Late 70's. > > Anybody heard about such diskettes? > > -- > Radoslaw Skorupka > Lodz, Poland > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
