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/* uIDE-8 74LS02 considerations */
=== uIDE-8 74LS02 considerations ===
The timing of the Z80 /RD signal is very tight, so the choice of NOR gate IC that you put at U2 is critical. Choose a fast part such as a 74'''F'''02. At least one manufacturer, Misubishi, makes a fast enough 74'''LS'''02 and that is what I used in my prototype. It has a propagation delay of 6-15ns, and the typical delay is somewhere in between, say 9ns. This appears to be the lowest speed the design will allow, although I have only tested with a few '02 variants. If in doubt, check the manufacturer's datasheet and don't buy anything with an average propagation delay larger than say 9ns. I've listed the delay times for several different '02 logic chips below. It's quite surprising what the propagation time range is for parts that are supposedly "standard".
Note: In the table, "Likely" means "my best guess based on the published proapgation delay times". Avoid anything that is "Not comaptible".
'''74??02 Propagation times'''
{| class="wikitable"
|-
! Maker / type !! H-L tPHL min !! L-H tPLH min !! H-L tPHL max !! L-H tPLH max !! Datasheet !! Comment
|-
| Motorola SN74ALS02 || 14 || 14 || 22 || 22 || http://pdf1.alldatasheet.com/datasheet-pdf/view/5703/MOTOROLA/SN54LS32SN74LS32.html || Not compatible
|-
| TI SN74LS02 || 8 || 12 || 15 || 22 || http://www.ti.com/lit/ds/symlink/sn74ls02.pdf || Not compatible(tested)
|-
| Hitachi 74LS02 || 10 || 10 || 15 || 15 || http://pdf1.alldatasheet.com/datasheet-pdf/view/63971/HITACHI/74LS02.html || Not compatible
| Mitsubishi 74LS02 || 6 || 6 || 15 || 15 || http://www.datasheetspdf.com/datasheet/download.php?id=770368 || Compatible (tested)
|-
| Philips/NXP ALS02 || 2 || 2 || 10 || 12 || http://pdf1.alldatasheet.com/datasheet-pdf/view/15231/PHILIPS/74ALS02.html || Likely not compatible
|-
| Fairchild LS02 || - || - || 18 || 15 || http://pdf1.alldatasheet.com/datasheet-pdf/view/51020/FAIRCHILD/74LS02.html || Not compatible
| TI 74S02 || 8 || 12 || 16 || 22 || http://www.futurlec.com/74S/74S02.shtml || Not compatible
|-
| Tesla 74ALS02 || || || 12 || || || Not Likely not compatible
|-
| TI 74F02 || 1 || 1.7 || 5.3 || 6.5 || http://www.ti.com/lit/ds/symlink/sn74f02.pdf || Likely compatible
