1.1 --- a/Electron.txt Sun Jan 29 20:40:59 2012 +0100
1.2 +++ b/Electron.txt Sun Jan 29 21:50:13 2012 +0100
1.3 @@ -7,7 +7,7 @@
1.4 the wide range of graphics modes, BBC BASIC, and extensible hardware and
1.5 software capabilities. Upon its introduction in late 1981, the BBC Micro
1.6 competed favourably against its immediate contemporaries, such as the ZX81 and
1.7 -VIC-20, as well as machine introduced slightly later, such as the ZX Spectrum
1.8 +VIC-20, as well as machines introduced slightly later, such as the ZX Spectrum
1.9 and Commodore 64. By producing a less expensive machine that retained certain
1.10 key features, the motivation was to bring BBC Micro technology to bear on the
1.11 lower end of the home computer market, albeit approximately two years after
1.12 @@ -41,14 +41,20 @@
1.13 performance benefits. Since the unexpanded Electron provides no convenient
1.14 means of installing ROM-based software - the Plus 1 and other expansion units
1.15 offered ROM cartridge slots, and various expansions provided ROM sockets - the
1.16 -improved Electron would ideally need to have a ROM cartridge slot. A
1.17 -side-benefit of adding this feature would arguably be an increased demand for
1.18 -cartridge-based software, potentially at a slightly higher price and also
1.19 -offering additional hardware features if necessary, thus making any cost
1.20 -incurred in the manufacture of the base unit more bearable.
1.21 +improved Electron would ideally need to offer a ROM cartridge slot as part of
1.22 +the unexpanded machine. A side-benefit of adding this feature to the base
1.23 +machine would arguably be an increased demand for cartridge-based software,
1.24 +potentially at a slightly higher price and also offering additional hardware
1.25 +features if necessary, thus making any cost incurred in the manufacture of the
1.26 +base unit more bearable.
1.27
1.28 The Slogger/Elektuur turbo board modified the system to permit the CPU to
1.29 access the bottom 8K of RAM without interruption by the ULA. This feature,
1.30 already known at Acorn during the Electron's design period, permitted
1.31 substantial improvements to performance and could also be incorporated into an
1.32 -improved Electron.
1.33 +improved Electron, although it presumably needs motherboard-level changes.
1.34 +Such turbo boards may have employed an additional RAM chip to avoid
1.35 +complicated changes to the memory access logic, since the ULA appears to
1.36 +access four memory chips at once to provide each byte, and it is therefore not
1.37 +possible to just "borrow" one of the chips in order to isolate 8K of RAM for
1.38 +direct access by the CPU.