On (10 Feb 95) [EMAIL PROTECTED] wrote... c> Date: Fri, 10 Feb 1995 14:04:36 +0100 c> From: Colin G Piggot <[EMAIL PROTECTED]>
> Well, Colin PIggot tried it with an 8MHz Z80C and the ASIC /did not/ want > to know. The bus, it seems, has to be at 6MHz... > > Simon Cooke c> Yeap! c> With the 8MHz clock and 8MHz CPU (Z84C008), nothing at all happened, c> Using a clock doubler with the ASIC's clock output and feeding this into c> the c> CPU worked *slightly*, ie a clock approx 12MHz, in phase with the ASIC. c> About half the time, the memory would clear and the startup message would c> pop up, then you could go into basic, then it would crash! c> (The startup took about 20% less time than with the original 6MHz clock!) c> Colin Piggot I tried using the FDC 8MHz clock on the z80B and 9 times out of 10 it powered up ok'ish the problems arose when I tried to boot from the floppy as at 8Mhz the short delay's required between FDC chip access's are compromised and it's running close to the limit of the ROM access times as well as the other I/O chips... Tha's why I want to stick a z84C50 cpu in as it has a built in programable wait-state generator to slow down bus accesses:-) Johnathan. PS for the test I was using SC_booter 120nS EPROM which is proably a bit better than the standard ROM's.... -- |Fidonet: Johnathan Taylor 2:2501/307.9 |Internet: [EMAIL PROTECTED] | | Standard disclaimer: The views of this user are strictly his own.
