[Coco] megaread HOW TO ?

[Allen Huffman]

On Apr 6, 2020, at 9:02 AM, Dave Philipsen <dave at davebiz.com> wrote:
> 
> 1) If you halt the CPU, you can deny it the ability to service interrupts because it could be that an interrupt comes in while the CPU is halted. 
> 
> 2) If you mask interrupts you also obviously prevent the CPU from doing the keyboard scan on a regular basis which could lead to lost characters. 
> 
> From all the conversations I’ve looked back at on Discord, the CoCoSDC does function as a ‘no-halt’ controller under OS9. However, as David Ladd pointes out, it probably masks interrupts to prevent anything from screwing around with MPI slot switching while a sector is being read. If that is the case, we could experiment with a modified driver that could be used for non-MPI systems which doesn’t mask the interrupts. 

Interesting. What did the KenTon SCSI and SuperIDE drivers don’t differently? I don’t recall ever letting the frustrating keyboard loss that I get on SDC?