1.1 --- a/ULA.txt Mon Oct 29 22:55:13 2012 +0100
1.2 +++ b/ULA.txt Tue Oct 30 00:04:27 2012 +0100
1.3 @@ -549,6 +549,27 @@
1.4 Electron) and other system-specific functions. Since the location usage is
1.5 generally incompatible, this region could be reused for other purposes.
1.6
1.7 +Increased RAM, ULA and CPU Performance
1.8 +--------------------------------------
1.9 +
1.10 +More modern implementations of the hardware might feature faster RAM coupled
1.11 +with an increased ULA clock frequency in order to increase the bandwidth
1.12 +available to the ULA and to the CPU in situations where the ULA is not needed
1.13 +to perform work. A ULA employing a 32MHz clock would be able to complete the
1.14 +retrieval of a byte from RAM in only 250ns and thus be able to enable the CPU
1.15 +to access the RAM for the following 250ns even in display modes requiring the
1.16 +retrieval of a byte for the display every 500ns. The CPU could, subject to
1.17 +timing issues, run at 2MHz even in MODE 0, 1 and 2.
1.18 +
1.19 +A scheme such as that described above would have a similar effect to the
1.20 +scheme employed in the BBC Micro, although the latter made use of RAM with a
1.21 +wider bandwidth in order to complete memory transfers within 250ns and thus
1.22 +permit the CPU to run continuously at 2MHz.
1.23 +
1.24 +Higher bandwidth could potentially be used to implement exotic features such
1.25 +as RAM-resident hardware sprites or indeed any feature demanding RAM access
1.26 +concurrent with the production of the display image.
1.27 +
1.28 ULA Pin Functions
1.29 -----------------
1.30