Date   : Sun, 22 Jul 2007 14:33:02 +0100
From   : jgh@... (Jonathan Graham Harston)
Subject: modern BBC remake

>Message-ID: <4f04bf1319info@...>
 
Sprow <info@...> wrote:
>  * 6845/video ULA/Teletext emulated in programmable logic
>    New set of registers to allow modes up to 1280x1024x256.
 
Oooh! Me Like!  I've got 20-year-old scribbles for implementing
"bigger" modes like 640x4col (MODE 8), etc., but they required a
video ULA that could supply a 8M clock to the CRTC. With the
relevant wiring the 6845 can access 512K of memory, dropping to
64K because of the way the BBC uses RA3 to trigger the zebra lines
and MA13 to trigger memory wrap-around. A hardware reimplem-
entation of a 6845 could have more than 14 memory address lines.
 
>    External tube connector configurable as either an IDE interface or Tube
 
Why either? They aren't mutually incompatible.
 
>  * System/user VIA
>    Possibly no printer port, replaced by a USB PIC and/or PS/2 keyboard
 
People keep suggesting ripping out facilities just for the sole
purpose of ripping them out. Ok, leave it for the user to decide
whether they solder on a printer socket, but don't remove that
choice from them.
 
-- 
J.G.Harston - jgh@...                - mdfs.net/User/JGH
BBC BASIC for Windows and Internationalisation
  See http://mdfs.net/Software/BBCBasic/Windows/ProgTips