1 Jun
2000
1 Jun
'00
3:03 p.m.
The Apple ][ floppy controller/6502 doesn't decode the bytes at the
floppy rotation speed. The 6502 copies the encoded bytes (de-serialized
by the controller) into memory, then decodes them after the sector
has been read. The sector interleave guarantees enough time to decode
the data before the next sector is available to be read.
I agree, it is an interesting piece of code...
clint
On Thu, 1 Jun 2000, Sellam Ismail wrote:
On 1 Jun 2000, Eric Smith wrote:
Sellam Ismail <foo(a)siconic.com> writes:
I'll take your word for it.
But can you dedcode 6&2 encoded bytes in
realtime on a 6502? Something
tells me it's not fast enough to do this.
If you're clever enough, you can do it. I previously cited several packages
that did it. Sellam wrote:
Oh well, I usually get the number wrong no matter how many times I look at
a ][ controller. At any rate, it's amazing.
I still maintain that the less than 256 byte Disk ][ boot ROM code is one
of the most amazing pieces of code ever written for a computing device.
Sellam International Man of Intrigue and Danger
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6 to be exact.
7 to be exact, if you don't count the boot PROM, which isn't really
part of the disk controller.