Subject: Sam-Hard disk filesystem In a message to Johnathan Taylor <02 Nov 94 12:03> [EMAIL PROTECTED] wrote:
>> So just use the good features of the >> various systems, make the nesesary >> comporimises needed to allow acceptable >> performance on a z80 machine ie if >> 32bit values slow it down use 16bit >> pointers and partition large HD's it >> smaller logical units, after all who >> needs to process more than 32Meg items on >> a z80? Cs> Hmmmmm... not sure. The 32bit values Cs> will perform pretty much no slow Cs> down if done right -- the drive itself Cs> will take the most time. True, depends if we hard-code the file-system using assembler and re-assemble drive parameter changes but addressing 32bit pointers using layered access to the file-system... can cause it to only ever manage one sector access per rotation rather than however many the interleve factor allows.. After all the z80 is an 8/16bit chip 32bit operations can be done but require a lot of organisation to be both bugless AND fast IMHO whilst 16bit ops can be done quite easily and rapidly using right but non-standard methods:-) Cs> Okay, agreed -- I won't use 510 byte sectors, 512 it is. Great! that'll improve the random access calculating:-) Cs> Now the question is: In our FAT do we Cs> want a way of searching <back> Cs> along the chain as well as forwards? Hmm, that's a tricky one! On ProDos due to extensive cache'n ALL random-access positioning is calculated from scratch each time its required... If Cache'n of the FAT and directory is going to be done, then random positioning on a file can be done in a similar fashion othrwise, PASS! I've not gone into NON-cpm low-level stuff so I don't know how it *can* be done:-( Or is the searching <back> along a chain to do with deleted file recovery? If so then I guess some form of recovery procedure should be considered, (I hadn't even thought of looking into UZI to see if that offers anything in that department, whoops <G>) Johnathan. ___ Olms 1.60 [Evaluation] -- |Fidonet: Johnathan Taylor 2:2501/307 |Internet: [EMAIL PROTECTED] | | Standard disclaimer: The views of this user are strictly his own.
