From: utzoo!decvax!ucbvax!C70:info-cpm Newsgroups: fa.info-cpm Title: CP/M Blocking and Deblocking Article-I.D.: ucb.1427 Posted: Sat Jun 26 06:24:04 1982 Received: Mon Jun 28 08:10:36 1982 >From ucivax!csuf!bruce@Ucb-C70 Sat Jun 26 06:23:53 1982 Ah HAH!!! I found the problem! It IS a bug in the Digital Research-supplied code. If you write the lower 128 bytes of a 256-byte UNALLOCATED blocked sector, everything is fine. If you then decide to read or write a sector in another block, everything is still fine; the original unallocated sector gets written out correctly. However, if you then decide to write the upper 128 bytes of the altered sector, the BIOS thinks it's still in the unallocated block, and decides not to preread the original sector. This causes you to lose the first 128 bytes of the sector. After wasting an entire day on this problem, I now have a working BIOS. It sure would be nice if Digital Research would send a bug fix for this problem. It only takes one instruction to fix... bruce ucbvax!ucivax!csuf!bruce