v089pfrb@ubvmsd.cc.buffalo.edu (Jeffrey C Murphy) (12/07/90)
I have several old disks which were formatted on the C1581 drive. I have
noted that when using RawCopy's trackread option and then selecting MFM
decode and IBM decode respectively, the tracks on the disk are decoded.
Question:
1) I know about decoding MFM formats, but what is the IBM decode
algorithm?
2) Do you have to bypass DOS in order to read a foriegn format?
3) Amiga Disk Drives Inside & Out (Abacus) seems to use many
absolute addresses in its programming examples, why?
Thanx in advance (resp. by email is preferable but not necessary)
Jeff M.rhialto@cs.kun.nl (Olaf Seibert) (12/08/90)
In article <49724@eerie.acsu.Buffalo.EDU> v089pfrb@ubvmsd.cc.buffalo.edu writes: > 3) Amiga Disk Drives Inside & Out (Abacus) seems to use many >absolute addresses in its programming examples, why? Because they are stupid. Don't buy their books. Many of them are translations from German books from the publisher Data Becker, and those books have a reputation of containing more incorrect than correct information. Unfortunately, unless you already have a lot of knowledge about the subject, you cannot tell what is correct and what isn't. But in their C64 intern book (yes I know it is old) that I have, I had to make lots of corrections. > Jeff M. -- Olaf 'Rhialto' Seibert rhialto@cs.kun.nl How can you be so stupid if you're identical to me? -Robert Silverberg
farren@well.sf.ca.us (Mike Farren) (12/11/90)
v089pfrb@ubvmsd.cc.buffalo.edu (Jeffrey C Murphy) writes: > 1) I know about decoding MFM formats, but what is the IBM decode >algorithm? Hmm? IBM decode? Do you mean GCR? IBM diskettes use a standard MFM decode, but a different data format than Amiga disks. > 2) Do you have to bypass DOS in order to read a foriegn format? Generally. DOS knows nothing about any other formats, except that there is the PCCopy program included with 1.3 - but then, it bypasses the normal disk routines, anyhow. > 3) Amiga Disk Drives Inside & Out (Abacus) seems to use many >absolute addresses in its programming examples, why? Because they are stupid. The folks that put out the Abacus books don't know thing one about how the Amiga really works - they seem to think that it's just some fancy C64. Avoid using their examples, unless you're willing to rework them to be "Amiga-friendly" (not always possible). -- Mike Farren farren@well.sf.ca.us
rob@spirits.ka.sub.org (Roland Bless) (12/15/90)
In article <2542@wn1.sci.kun.nl>, Olaf Seibert writes: > Many of them are translations from German books from the publisher Data > Becker, and those books have a reputation of containing more incorrect > than correct information. Unfortunately, unless you already have a lot That's true. One Example: The Big C-Book (AMIGA) from Data Becker ("Das grosse C-Buch":Bleek/Jennrich/Schulz). On page 82 they try to explain IN DETAIL how for()-loops in C work, but you guess it, they aren't able to do this correctly: for (i=0; i<5; i++) j+=2; is naturally equivalent by definition to: i=0; while(i<5) { j+=2; i++; }; Their version about it (WRONG!!): 1. Initialization of i (i=0); 2. Execution of the body (j+=2); 3. Incrementation of i; 4. Test the condition. #T->Step 2. #F->leave loop They emphasize differences between for() and while() loops (execution of the body before testing the condition at for()-loops) and show a wrong assembler listing of the compiler output. :-D It's really ridiculous. Greetings, Roland -- R o l a n d B l e s s |UUCP/Internet: rob@spirits.ka.sub.org | Kriegsstrasse 129 |BITNET: UKG5@DKAUNI2.BITNET FAX: +49211623818 | 7500 Karlsruhe - FRG |---------spirits--in--the--material--world---------| voice +49 721 857328 |"They built machines that they can't control" STING|