Re: [cbm4linux-users] a few questions

[Ryan U. <nem...@ic...>]

On Fri, Jan 09, 2004 at 02:15:58PM +0100, Michael Klein wrote:
>=20
> Warp mode sends raw (unchecked) GCR data over the bus, leaving decoding
> and checksumming to the Linux side. This is normally significantly
> faster despite the fact that more data is transferred (325(?) bytes
> instead of 256). Thus, the Linux host catches in fact more block
> checksum errors (23) than in non-warp (turbo/original) mode, where the
> 1541 automatically retries and eventually succeeds.
>=20
> This means also that warp is generally safer than turbo, because turbo
> doesn't catch transfer errors (data sent by 1541 !=3D data received by PC=
)!

Interesting!  In warp mode, does the PC retry in case of errors?  Along
the lines of my original question, is there a particular reason _not_ to
use warp mode under any set of circumstances?  It seems that extra speed
doesn't very often come without a price of some sort....

After copying some disks, I'm also wondering if d64copy tries to do
anything about the most common forms of copy protection (1/2 track,
missing blocks, etc).  For example, I dumped Winter Games by Epyx, which
I was almost certain had some sort of copy protection on it.  The copy
process completed without error on both sides, however.  (I haven't
tested the resulting images.)

> > 3) Is there, or would it be possible to construct, a program to do head
> > alignment of a commodore drive using a x*1541 cable and a PC?
>=20
> Absolutely possible. Anything you can do from a C64 should be also
> doable from a Linux PC (except highly timing-sensitive drive/host
> communication stuff).
> For inspiration, here's a small GTK+-based tool to measure the drives
> rotation speed:
>=20
> http://a98.shuttle.de/~michael/rpm1541/
> (Use scratch disk!)

Very cool.  Thanks for your informative reply!

--=20
Ryan Underwood, <ne...@ic...>