# HG changeset patch # User Paul Boddie # Date 1367181793 -7200 # Node ID 751a7ca72c0549e3b9b7fdd5505166722a908ff0 # Parent fc68c722a834972ff81b48e7bca0d20f4f0ed767 Added a note about a mechanism to allow more flexible colour output, marking the palette definition section as an enhancement. Made a minor fix in the RAM section. diff -r fc68c722a834 -r 751a7ca72c05 ULA.txt --- a/ULA.txt Sun Mar 10 17:47:32 2013 +0100 +++ b/ULA.txt Sun Apr 28 22:43:13 2013 +0200 @@ -159,8 +159,8 @@ supposedly a replacement for the TMS4164-15 amongst many other parts. Similar parts include the NTE2164 and the NTE6664, both of which appear to have largely the same performance and connection characteristics. Meanwhile, the -NTE21256 appears to be a 16-pin replacement that with four times the capacity -that maintains the single data input and output pins. Using the NTE21256 as a +NTE21256 appears to be a 16-pin replacement with four times the capacity that +maintains the single data input and output pins. Using the NTE21256 as a replacement for all ICs combined would be difficult because of the single bit output. @@ -344,8 +344,8 @@ input/output and the Caps Lock LED) would need to be reassigned and bit 0 potentially being made available for use. -Palette Definition ------------------- +Enhancement: Palette Definition +------------------------------- Since all memory accesses go via the ULA, an enhanced ULA could employ more specific addresses than &FE*X to perform enhanced functions. For example, the @@ -366,6 +366,12 @@ from the ULA, it is likely that the ULA is expected to provide only "high" or "low" values. +Short of adding extra outputs from the ULA (either additional red, green and +blue outputs or a combined intensity output), another approach might involve +some kind of modulation where an output value might be encoded in multiple +pulses at a higher frequency than the pixel frequency. However, this would +demand additional circuitry outside the ULA. + Flashing Colours ----------------