qwertykeyboard wrote:
How many of each should I buy? Would two of each be ok?
It depends on your budget. The common gates (AND, OR, etc.) are likely the ones you will mostly use. So more of those might be a good idea. A couple of C-D flops (74xx74) and J-K flops (74xx109) would be good to have. I have used bus drivers (74xx540 and 74xx541) as I/O devices in some of my designs, which may be useful to you. A transceiver, such as a 74xx245, is also useful and could be used as a bi-directional I/O device (although the 65C22 is much better for that purpose).
The good thing is that discrete logic in PDIP packages is still plentiful and relatively inexpensive. However, it isn't going to stay that way, so a little bit of hoarding now may prove to be a wise thing to do.
As far as which logic family to purchase, consider that in most cases, 74HC ("high-speed CMOS") is reliable in systems running at up 8 MHz, and output rise and fall times are moderate. Beyond that, go with 74AC ("advanced CMOS") or 74AHC ("advanced high-speed CMOS"). 74AC device outputs have an extremely fast rise and fall time, and can cause problems if construction methods are not carefully thought out. 74AHC is friendlier in that respect, but doesn't have as much drive. It all depends on what you plan to do.
I recommend you avoid using TTL devices, such as 74LS or 74F. They are power-hungry and produce TTL-level outputs, not CMOS. Attempting to drive the input of a CMOS device from the output of a TTL device may cause switching problems, unless the CMOS device has TTL-compatible inputs. Such devices will have a 'T' in the part number, such as 74ACT541.