> Didn't know there were a 1.7 ROM. Thought you had to > upgrade the cache to 32K to attain speed over 10MHz.
1.7 ROM was for 8k cache. 1.8 ROM is for 32k cache the 1.8 has the code to access the 32k. It is 65816 code, so the CPU on the TWGS not only runs as the the Apple IIgs CPU, but the CPU also takes care of cache logic and perhaps slowdown logic. I've run 5 different TWGS boards at 12.5mhz with the 1.7 ROM and 8k cache. The cache does speed things up (I also have a 32k cache board), but it is independent of the CPU speed. There used to be the need for GAL chips of a certain version to run at faster speeds. The first batches of 20mhz 65816 had faulty engineering. Running certain instructions at high speed would crash the processor. The GAL chips on the TWGS got around this by slowing the CPU down when the sensitive instructions were encountered. I wonder if the TWGS board will run its fastest with no GALs installed. I'll have to try removing them one of these days and see if it runs any faster. I'm pretty sure they are all wired in parallel, and it doesn't matter which location you have them plugged into. Rich -- Apple2list is sponsored by <http://lowendmac.com/> and... / Buy books, CDs, videos, and more from Amazon.com \ / <http://www.amazon.com/exec/obidos/redirect-home/lowendmac> \ Support Low End Mac <http://lowendmac.com/lists/support.html> Apple2list info: <http://lowendmac.com/lists/apple2.html> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[email protected]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/apple2list%40mail.maclaunch.com/> iPod Accessories for Less at 1-800-iPOD.COM Fast Delivery, Low Price, Good Deal www.1800ipod.com
