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FPGAmstrad

554 bytes added, 10:55, 27 September 2017
/* Instruction timing : talk about r005.8.16c4 */
During this work, I remark an instruction that seems badly classified on plustest.dsk : 2A LD HL, (nn). This instruction does not use MEM_WR and is not a 5T M1 instruction. So it shall be using 4 NOPs instead of 5 NOPs. LD (nn), HL does take 5 NOPs (because it does use MEM_WR instruction), as in plustest.dsk testbench here for this instruction.
 
===== Tests on real CPC (by DanyPPC) =====
[http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/need-plustest-dsk-testbench-5-output-on-original-cpc-6128/ CPCWiki's forum : Need plustest.dsk testbench 5 output on original CPC 6128]
 
So 2A is really during 5 NOPs... perhaps MEM_rd has to be slow down with one WAIT_n like for MEM_wr. Perhaps in this case 5T's instruction has not to be slow down. I have to fork r005.8.16c3 to test that.
 
About testbench border effects, I think that IO_ACKed instructions has to be under same rules (MEM_wr, modulo 4 etc)
=== Test of a real Zilog 80 ===
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