John Summerfield wrote: > > Not quite - the key for this purpose is included in the length of the > data block. > > (65535 * 255 * 65535) is still fairly large. More than 2.3 Gbytes. >
Don't think so. CKD stands for count,key,data. Each record on a track has a count area, optional key area and optional data area. The format of an 8-byte count area is CCHHRKDD CC is a 16 bit cylinder number, HH is a 16 bit head number, R is a 8 bit record number, K is a 8 bit key length and DD is a 16 bit data length. The data length does not include the key length. And 65535*65535*255*(255+65535) is a little larger than 2.3G. In fact, a 3390-3, which has limits well below these theoretical maximums, is about 2.3G in size. Of course, the theoritical maximum does break down in a number of areas. To do anything useful, record 0 must be `standard' (ie no key and an 8 byte data area). The device characteristics information has only a three byte field for track capacity. And I know for a fact that Hercules would break if the max track size exceeds 64K ;-) Greg
