1.1 --- a/ULA.txt Thu Feb 21 20:04:40 2013 +0100
1.2 +++ b/ULA.txt Sat Mar 09 23:36:21 2013 +0100
1.3 @@ -126,6 +126,25 @@
1.4 with approximately 15 blank lines above and below the picture. Thus, the start
1.5 of the picture could be chosen as 38 lines after the start of vsync.
1.6
1.7 +RAM Integrated Circuits
1.8 +-----------------------
1.9 +
1.10 +The documentation for the Electron mentions 4164-15 RAM chips for IC4-7, and
1.11 +the Samsung-produced KM4164 series is apparently equivalent to the Texas
1.12 +Instruments 4164 chips presumably used in the Electron.
1.13 +
1.14 +The TM4164EC4 series combines 4 64K x 1b units into a single package and
1.15 +presumably could be used to replace the Electron's separate ICs, but it has 22
1.16 +pins providing 3 additional inputs and 3 additional outputs over the 16 pins
1.17 +of the existing modules, presumably allowing concurrent access to the packaged
1.18 +memory units.
1.19 +
1.20 +As far as currently available replacements are concerned, the NTE4164 is a
1.21 +potential candidate. According to the Vetco Electronics entry, it is
1.22 +supposedly a replacement for the TMS4164-15 amongst others. Meanwhile, the
1.23 +NTE21256 appears to be a 16-pin replacement for all four ICs that maintains
1.24 +the single data input and output pins.
1.25 +
1.26 See: Acorn Electron Advanced User Guide
1.27 See: http://mdfs.net/Docs/Comp/Electron/Techinfo.htm
1.28 See: http://en.wikipedia.org/wiki/PAL
1.29 @@ -138,6 +157,14 @@
1.30 http://www.pembers.freeserve.co.uk/World-TV-Standards/Line-Standards.html
1.31 See: TM4164EC4 65,536 by 4-Bit Dynamic RAM Module
1.32 http://www.datasheetarchive.com/dl/Datasheets-112/DSAP0051030.pdf
1.33 +See: KM4164B 64K x 1 Bit Dynamic RAM with Page Mode
1.34 + http://images.ihscontent.net/vipimages/VipMasterIC/IC/SAMS/SAMSD020/SAMSD020-45.pdf
1.35 +See: NTE4164 - IC-NMOS 64K DRAM 150NS
1.36 + http://www.vetco.net/catalog/product_info.php?products_id=3680
1.37 +See: NTE21256 - IC-256K DRAM 150NS
1.38 + http://www.vetco.net/catalog/product_info.php?products_id=2799
1.39 +See: NTE21256 262,144-Bit Dynamic Random Access Memory (DRAM)
1.40 + http://www.nteinc.com/specs/21000to21999/pdf/nte21256.pdf
1.41 See: Acorn Electron Service Manual
1.42 http://acorn.chriswhy.co.uk/docs/Acorn/Manuals/Acorn_ElectronSM.pdf
1.43