Spectrum Computing

New release of SpecEmu, available at https://specemu.zxe.io.

Yes, your post is spot on. The emulators keep the PC pointed to HALT, only contend by PC+1 (those which got it right - others still contend by PC). The PC is then stepped in the interrupt handling code when it knows HALT is being executed. If HALT would actually increase the PC, it would be more di...

is it really like that? i was sure that Z80 keeps reading the memory. that explains why HALT is not ts-precise (i.e. CPU checks for /INTR each 4ts instead of each 1ts). it would be logical to either just loop and check for /INTR (and /NMI) on each tick if there is no command fetching — or make HALT...

Some time ago I decided to locate, rename (according to the TOSEC naming convention ) and collect all those amazing pieces of software that many people have been writing over the last decades to test their emulators. Some of them have been really hard to track down, as they were usually posted on fo...

BTW, many thanks to @TheMartian, who is testing all the tapes from Patrik's Zilog Z80 Test Suite on many of her machines, so that finally everything is 100% tested once and for all.

Some of the results can be checked here.

i dont remember old discussions details now, but do you mean even Patrik himself never tried it on a real hw :? yep... I was there when Patrik was working on the new releases of his test suite. We knew about new discoveries about the CCF/SCF instructions and the flags of block instructions, which m...

couldn't be all, not every one failed Patrik's test before afair, otherwise too many people would complain Actually, I don't know of anyone who specifically tried z80memptr.tap on a real Zilog or NEC on Sinclair hardware until yesterday. People usually try z80full.tap and z80ccf.tap. I have a Russi...

TheMartian wrote: ↑Fri Dec 01, 2023 1:05 pm Hi!

Does this happen in all Z80 models, or just NEC? I'm curious.

I'll try later to execute on my machines. Any suggestion or request?

Confirmed on Zilog and NEC. I assume that ST CMOS models also have this behaviour, but it is not confirmed.

USSR and MME models could behave differently.

I've discovered a new undocumented behavior of the inir/indr/otir/otdr instructions: As in cpir/cpdr/ldir/lddr, when the repeat condition is met, the CPU generates an extra M-cycle of 5 T-states to decrement PC. This M-cycle performs additional flag changes ( discovered and cracked by David Banks (A...

Hi @ZjoyKiLer, Great project! For the UK readers, please could you confirm this is the correct board from Olimex board that you mention? https://thepihut.com/products/olimex-esp32-sbc-fabgl?variant=42484410253507 Are there any plans for English language installation video please? Thanks Peter Hey, ...

Presentation of the new version 1.0 rc2

New version of SpecEmu released: https://specemu.zxe.io/download/specemu-3.4.b240723.zip

New version of SpecEmu released: https://specemu.zxe.io/download/specemu-3.4.b200723.zip

After I'd downloaded specemu-3.4.b110623, MalwareBytes warned me it considered one of the zip's contained files " emulib.dll " a threat: Neshta.Virus.FileInfector.DDS Symptoms To gain persistence, Virus.Neshta changes the default value for the registry key HKEY_CLASSES_ROOT\exefile\shell\...

XoRRoX wrote: ↑Mon Jun 12, 2023 7:07 pm Thanks again

I keep track of new emulator releases by using an RRS feed of http://www.emucr.com/ which I load into Feedly. Now SpecEmu releases through above website are also included in it.

Great! Thanks!

PeterJ wrote: ↑Mon Jun 12, 2023 7:09 pm Is that GitHub hosting you are using there?

No, it's my own server. The web is very basic, I'll improve it in the coming days.

@ZjoyKiLer Thank you very much for this. I found that this Version of SpecEmu shows v.3.3 in the "Help / About SpecEmu"-Window: https://i.postimg.cc/wMPn4hmp/Spec-Emu-v3-4-2023-06-09-Spec-Emu-v3-3-2023-06-09.jpg while the ChangeLog.txt show this as v3.4 build 09/06/23. On first try I get ...

For those looking for the latest releases of SpecEmu:
https://specemu.zxe.io

Very interesting project for the Raspberry Pi Pico. Thanks for posting.

BTW, I see that it uses my Z80 core (https://github.com/redcode/Z80)

From the README:

I've moved to the Redcode Z80 emulator as:

• It comes with a test suite
• It is much faster than the previous emulator

THANK YOU VERY MUCH FOR THIS!!

THANK YOU!!

I forgot to mention that the latest version of the Z80 Block Flags Test can be downloaded from its official repository: https://github.com/MrKWatkins/ZXSpectru ... ctionFlags

Hi everybody, I recently thought I'll test my Z80 CPU emulator implementation using @Patrik Rak's z80test tester. Since currently my emulator only handles the documented flags, I used the z80doc variant. I was thrilled to see that almost all tests passed. However, there were 4 tests that did not. M...

Is this new behaviour as described in the Z80 CPU User Manual page 18 When an EI instruction is executed, any pending interrupt request is not accepted until after the instruction following the EI is executed. This single instruction delay is necessary when the next instruction is a return instruct...

This is very unlikely from a hardware standpoint. This would require extra circuitry to carry forward a signal into the next machine cycle. There is a much simpler course of action: IFF2 is copied to IFF1 at the rising edge of the last T state, the same time the int line is sampled. Visual Z80 Remi...