Re: Theorizing: cloning CBM electronics with modern technology.

From: Gerrit Heitsch <*gerrit_at_laosinh.s.bawue.de*> Date: Wed, 23 Mar 2022 21:41:37 +0100 Message-ID: <02937935-87f7-ffd6-8fba-ac6d375b5625_at_laosinh.s.bawue.de> · gerrit_at_laosinh.s.bawue.de

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.

  Gerrit