General Description: When designing into a Spartan part, 4000E library is used as the design library. What 4000E library components can not be used in Spartan.
Solution
These components must be avoided when targeting Spartan even though they are technically available in the 4000E library.
1) Asynchronous RAM
Do not use the following components: RAM16x1, RAM32x1, and other available depths
The following components may be used because they are synchronous: RAM16x1S, RAM32x1S, RAM16x1D, ROM16x1, and other available depths
Also, do not use LogiBLOX to create asynchronous RAM components
2) Edge Decoders
Do not use the following components: DECODE4, DECODE8, DECODE16
3) Wired-AND
Do not use the following components: WAND1, WAND4, WAND8, WAND16, WOR2AND
4) Mode Pins as Usable I/O
Do not use the following components: MD0, MD1, MD2