Simbo stopped posting after page 1. Maybe he doesn't like me..... But I would love some MagiC rom images to try..... but where?
Being slightly mad... I looked in my pile of old ICs....
i found some 7474, and 7400 chips (actually many)... I decided to try them in the LASCAN and 16mhz OC pcb sockets.
Well my 8mhz cpu still doesn't like 16mhz (I try to act suprised!), these old chips work perfectly. (The frequency counter reports 16mhz when jumpered so- the Fuji icon appears, then bombs!- like before)
(Actually, the datasheet says the 7474 is rated to 15mhz!, the LS is good for 25mhz) Nearly good enough given tolerances......!, but Nikolas/Ego says HC types was better for his overclock.....
Perhaps the 74LS00 nand gate is speed limited in the LS type..... datasheets I have don't specify a max operating frequency.
So, jumpered to 8mhz the overclock board supplies 8mhz through these chips to the cpu quite nicely.....and stable. (I'll try the 16mhz cpu soon with these old chips for fun!,and test Nikolas's result)
And the LASCAN functions fine with a 7474 in place of the LS version. (I dont have any 7410 chips to change the 74LS10 though)
The old chips have a higher power consumption, and maybe a dirtier signal.. but they are still pin compatible, and are TTL chips.........
Actually nearly triple the power consumption... 30mA vs 8mA for *74.
Just having fun here- and no major use yet for nearly 100 old TTL chips. (Like maybe 20-30 years old!.. but new old stock, NOS)
And no 74151s... for HD FDD use
You will have to PM me your address Mr Shredder. And maybe find a nice person to solder this little board into your STE. (maybe also we can trade a Sony drive for the board?!)
You can be the offical prototype tester!