On 3/23/22 22:36, Claudio Sánchez - Tokafondo wrote: >> On 3/23/22 21:08, ruud_at_Baltissen.org wrote: >>> Hallo groepaz, >>> >>> >>>> no, he probably means this: >>>> >>>> https://github.com/ThKattanek/1541-rebuild >>> >>> Thank you for the link! >>> >>> But to be honest, I lean more to an even simpler solution: >>> connecting the SD card directly to the 6522. But I'm sure this will >>> come with a penalty: speed. IIRC the 1541 collects a byte from the >>> floppy every 23 uSec. Collecting 8 bits by bit banging and rolling >>> them into a byte will cost much more time: >>> - toggle clock bit of SD >>> - read bit into bit 7 >>> - roll bit into Carry >>> - roll Carry into end byte >>> - toggle clock bit of SD >>> Rough guess: 17 uSec for one bit? >>> >>> Let's face it (again) Ruud, the uController solution is better. >> >> It also means that it emulates the mechanic 100%, any floppy speeder >> or code loaded into the 1541 should still work with it and that was >> the idea behind it. Also most copy protections shouldn't be able to >> detect anything off. Weak bits might be a problem though. > > Does any of the CBM drives allow to control even the voltage levels of > the signals sent or received from the heads? Or make the motor go faster > or slower? No, that's digital. And the drive motor is fixed in speed, it's the clock for the shift register that gets varied and results in the 4 different data rates. > Where in the circuit is the frontier between digital, bits that comes in > and go out, and analog, electric signals going to and coming from the > magnetic surface of the disk? On the short board? I'd say between UE4 and UD3, the latter being a 74LS86 and the former a LM311/UA311 for incoming bits. Outgoing... on the outputs of UD2 (7417) GerritReceived on 2022-03-24 07:00:02
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