Date   : Tue, 01 Dec 2009 03:13:45 +0000
From   : kevin@... (Kevin Bracey)
Subject: Tube - I/O processor memory questions

Jonathan Graham Harston wrote:
>
> Why re-invent the wheel? Just use OSWORD &FF -
> mdfs.net/tube/Z80/OswFF.src
> (Give me a couple of days and I'll finish OswFFv2 which does
> sideways ROM/RAM)
>   
Sweet - that's roughly the sort of thing I want to do. I'd be intending 
to use the faster 256-byte transfer calls though, as I only ever need to 
do 256-byte transfers (not even multiples of that). And I'd also need 
the implementation to have a non-Tube case (where it would be used just 
for SRAM->main RAM transfers, by code running from ROM).

One thing - surely the use of &70-&7F isn't legal - we've established it 
belongs to the Tube code... Also, what's the point of the 900->2500 
copy? In that form, couldn't you just as well run it at FFFF2500?

Hmm, just been trying to benchmark yours against OSWORD &42, and I 
eventually realised that TIME wasn't going up - I think you need to 
manually re-enable interrupts in the OSWORD handler for a slow call like 
that (as well as for claiming the Tube).

Kevin