On the same vain as my last question about LDIR behavior, which wouter_ kindly responded in a very thorough fashion (thank you again btw!), I am confused about another behavior, this time about LD(HL), A.
I am seeing different behaviors from the openMSX code and mine when running it. Here's the scenario:
#0D43> list 0D39 79 LD A, C 0D3A 32 FF FF LD (#FFFF), A 0D3D 21 00 FF LD HL, FF00 0D40 3E 0F LD A, #0F 0D42 77 LD (HL), A > 0D43 BE CP (HL) 0D44 20 08 JR NZ, #08 0D46 2F CPL 0D47 77 LD (HL), A 0D48 BE CP (HL) 0D49 20 03 JR NZ, #03 0D4B 25 DEC H 0D4C 18 F2 JR #F2
I am stopped right after the LD (HL), A instruction and up to this point, all the registers, including HL and the memory location it points to were perfectly sync'ed between my emulator and openMSX.
Here's a list of the last executed instructions and how it affected some registers/flags (the status on the right of the instruction is what it looked like BEFORE the execution of the instruction):
0D43 BE CP (HL) #0D43 #BE - A: #0F B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#0F) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0 0D42 77 LD (HL), A #0D42 #77 - A: #0F B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#00) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0 0D40 3E 0F LD A, #0F #0D40 #3E - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#00) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0 0D4C 18 F2 JR #F2 #0D4C #18 - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#00) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0 0D4B 25 DEC H #0D4B #25 - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #80 L: #00 - HL: #8000(#F0) SP: #FFFF - S: 0 Z: 1 H: 0 P/V: 0 N: 1 C: 0 0D49 20 03 JR NZ, #03 #0D49 #20 - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #80 L: #00 - HL: #8000(#F0) SP: #FFFF - S: 0 Z: 1 H: 0 P/V: 0 N: 1 C: 0 0D48 BE CP (HL) #0D48 #BE - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #80 L: #00 - HL: #8000(#F0) SP: #FFFF - S: 0 Z: 1 H: 1 P/V: 0 N: 1 C: 0 0D47 77 LD (HL), A #0D47 #77 - A: #F0 B: #F0 C: #F0 D: #FF E: #FF H: #80 L: #00 - HL: #8000(#0F) SP: #FFFF - S: 0 Z: 1 H: 1 P/V: 0 N: 1 C: 0
As you can see from the last two statuses:
#0D42 #77 - A: #0F B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#00) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0 #0D43 #BE - A: #0F B: #F0 C: #F0 D: #FF E: #FF H: #7F L: #00 - HL: #7F00(#0F) SP: #FFFF - S: 0 Z: 0 H: 1 P/V: 1 N: 1 C: 0
A became 0x0F and right after the memory location pointed by HL was loaded with 0x0F.
However on openMSX this didn't happen:
Initially I thought it was becase of the memory layout, but apparently we have the same layout active, you can see openMSX's is:
$0 $0000 0 $1 $4000 0 $2 $8000 3 $3 $C000 3
And the machine descriptor:
<primary slot="0">
<ROM id="Temporary Machine">
<mem base="0x0000" size="0x8000" />
<rom>
<sha1>2f997e8a57528518c82ab3693fdae243dbbcc508</sha1>
<filename>/Users/fcoury/code/msx_emulator/cbios_main_msx1.rom</filename>
</rom>
</ROM>
</primary>
<primary external="true" slot="1" />
<primary external="true" slot="2" />
<primary slot="3">
<RAM id="Main RAM">
<mem base="0x0000" size="0x10000" />
</RAM>
</primary>
And my emulator is working the same way:
#0D44> st
Cycles: 1311
Breakpoints: []
Primary Slot Config: 11110000
Slot #0: ROM path=Some("/Users/fcoury/code/msx_emulator/cbios_main_msx1.rom") base=0x0000 size=0x8000
Slot #1: Empty
Slot #2: Empty
Slot #3: RAM base=0x0000 size=0xFFFF
Segment 0: 0x0000 - 0x7FFF - base: 0x0000 - (slot 0)
Segment 1: 0x8000 - 0xFFFF - base: 0x0000 - (slot 3)
Memory page 0 (0x0000 - 0x3FFF): primary slot 0 (ROM path=Some("/Users/fcoury/code/msx_emulator/cbios_main_msx1.rom") base=0x0000 size=0x8000)
Memory page 1 (0x4000 - 0x7FFF): primary slot 0 (ROM path=Some("/Users/fcoury/code/msx_emulator/cbios_main_msx1.rom") base=0x0000 size=0x8000)
Memory page 2 (0x8000 - 0xBFFF): primary slot 3 (RAM base=0x0000 size=0xFFFF)
Memory page 3 (0xC000 - 0xFFFF): primary slot 3 (RAM base=0x0000 size=0xFFFF)
Any ideas why doing LD (HL), A when A is 0x0F and the memory segment is mapped to RAM doesn't work?
Thank you!
