Issue # 38 DTACK GROUNDED Newsletter - January 1985
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DTACK GROUNDED Newsletter
· 1 year ago
... number in D2, and a PHYSICAL (not logical) sector # in D3. Here is code that will do the job, including a test for a legal logical sector #: 1 CMPI.L #1279,D0 2 BHI DISKERROR 3 MOVE.W D0,D1 4 LSR.W #4,D1 5 MOVE.W D0,D2 6 LSR.W #3,D2 7 MOVE.W D0,D3 8 ADD.W D2,D3 9 ANDI.W #7,D3 10 ANDI.W #1,D2 That's it! That's all it takes. An explanation: Page 13, Column 2 A digression: We have a choice between skewing the logical-vs-physical sectors between side 0 and side 1, while using an 8K disk buffer, or NOT skewing the sectors and using a 16K disk buffer. There is a potential 5.5% data throughput performance gain if no skewing and 16K buffers are us ...
