gooddi said:

thans for your very useful information.

i will investigate 74F253S.

and which one is PAL ? Please tell me more about PAL.

did you mean ASG? i can't find PAL on my logic board.

WIKIPEDIA say that about PAL

 - BMU0/1, TSM, TSG,LAG,.....

RIGHT?

Thanks again, techknight.

Click to expand...

PAL - Programmable Arith-Logic Unit, similar to an EPROM/ROM. They only contain a few bytes of code (less than 500 bytes, but some can be 2 - 4 kb in size) usually for the I/O Chips and not the main CPU. They also behave like tiny cpus - 4 bit jobs like in a calculator, doing repetitive loops with the I/O Chips.

Fun Stuff they are.

Side-Rant-o-Fact - the Apple II Disk Drive Card has 2 PALs for the Disk Read/Writes. (I forget which ones) If one blows, it becomes a killer card that kills a couple of chips inside the Disk Drive itself. If the other one blows, any disk you put to either drive, that disk gets erased.