Re: Informations about JiffyDOS

From: Marko Mäkelä (
Date: 2001-03-15 10:21:06

On Thu, 15 Mar 2001, Carlsson, Anders wrote:

> I thought the VIC-20 hardware was inferior, and can't transfer data as
> fast as the C64 can (new serial devices or something).

No, in fact the VIC-20 is faster than the C64.  JiffyDOS doesn't make use
of the fast serial bus (burst mode) on the C64, because it doesn't
require any hardware modifications.

The serial bus interface in the 1541 is implemented using the same chips
as in the VIC-20: the 6522 VIA.  Since there is a 1541 part of JiffyDOS, I
see no technical reason why there couldn't be a JiffyDOS for the VIC-20.
The only reason I see is commercial: the market would be too small.  I
don't know if there are any copyright reasons why a 3rd party couldn't
develop JiffyDOS for the VIC-20 by reverse-engineering its C64 version.

> Also, it was for compatibility reasons the 1541 didn't utilize faster
> routines from the beginning. I might be wrong, but I think I've read
> about this before.

There have been some rumours that Commodore originally planned to use the
serial interface of the 6522 VIA, but failed and decided to use programmed
I/O pins instead.


This message was sent through the cbm-hackers mailing list.
To unsubscribe: echo unsubscribe | mail

Archive generated by hypermail 2.1.1.