Search found 7362 matches

by hoglet
Tue Aug 14, 2018 7:48 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Maybe I'm too simple-minded now but the above log suggests that the flags changed after PUSH AF and before that H = C as expected. Before the PUSH AF, the flags are what's being predicted by the emulation. After the PUSH AF, the value that is pushed to the stack represents "reality" At the point, t...
by hoglet
Tue Aug 14, 2018 7:41 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10947

Re: Open Source Logic Analyzer Experiments

It should work fine on a Model B - I've used this quite extensively.

But that trace looks very broken.

Can you zip up the data.bin and upload it and I'll take a quick look?

Dave
by hoglet
Tue Aug 14, 2018 6:30 pm
Forum: hardware
Topic: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male
Replies: 27
Views: 471

Re: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male

Master != Model B

i.e. they are very very different environments.
by hoglet
Tue Aug 14, 2018 6:29 pm
Forum: hardware
Topic: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male
Replies: 27
Views: 471

Re: Raspberry Pi B+ compatible GPIO Extender 40-way Ribbon Cable Female-Male

Are you using a shorted cable now? How long exactly?

I've found even 30cm is marginal on a heavily populated machine.

There is a reason I think that the real Acorn Co Pros only have a 15cm cable.
by hoglet
Tue Aug 14, 2018 6:25 pm
Forum: hardware
Topic: Z80 Tube Speed
Replies: 2
Views: 107

Re: Z80 Tube Speed

In his results for the ClockSP program, JGH lists an Acorn Z80 co-processor running at 4Mhz. Elsewhere in these forums someone commented that running at 6Mhz, the Z80 processor was one of the fastest Z80 systems of the 1980s. Did both variants exist or was someone mistaken? I know the processor its...
by hoglet
Tue Aug 14, 2018 6:01 pm
Forum: hardware
Topic: Open Source Logic Analyzer Experiments
Replies: 201
Views: 10947

Re: Open Source Logic Analyzer Experiments

Not sure what I have missed? (I am using Myelin's cart board, on a Beeb using Tube interface. both jumpers in place and 3 wires hooks to 6502 to give missing signals. I think the Linux kernel is getting in the way... If you do a dmesg, do you see any lines referring to usbtest? [67235.159416] usbte...
by hoglet
Tue Aug 14, 2018 5:54 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Something that puzzles me a little bit is how the Russian MEMPTR/WZ investigators know WZ when BC <> 1 during LDxR, as it must be overwritten during IM 1 and 2 interrupts. I doubt they used any hardware, but perhaps they added pull-up/pull-down resistors on the data bus to set the IM 0 opcode to E9...
by hoglet
Tue Aug 14, 2018 4:46 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Have you tested CPxR, INxR and OTxR during interrupts? I don't see why the repeat logic would differ from LDxR. No I haven't, so I've just now tried INIR. You are right, when interrupted it seems to be following the same pattern as LDIR. My decoder is currently wrong on this case, so I'll fix and r...
by hoglet
Tue Aug 14, 2018 3:38 pm
Forum: acorn atom
Topic: Atom 2k18 ?
Replies: 41
Views: 1276

Re: Atom 2k18 ?

Unfortunately the Xilinx tools are completely rubbish when dealing with warnings. It seems their FPGAs tools are much worse than their CPLD tools in this regard. I get 289 warnings for this project, mostly unconnected ports, signals not being used, logic being optimised. But I agree it is a real pai...
by hoglet
Tue Aug 14, 2018 3:25 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Changed, then changed back, as right first time, I think. That works, nice optimization! 10 code%=&E000 20 FOR I%=0 TO 3 STEP 3 30 P%=code% 40 [OPT I% 50 .test 60 DI 70 LD A,(&0000) 80 \ work out the value of MEMPTR without disturbing it 90 LD IX,&FFFF 100 \ copy bit 13 of MEMPTR INTO E 110 BIT 0,(...
by hoglet
Tue Aug 14, 2018 2:49 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

A minor point: LD HL,loop is needed only once before the loop as you're adding 0 to L until bit 13 flips. Change LD HL,loop to RRA and insert LD HL,loop before .loop and all the NOPs can be deleted! I don't think that is going to work, because CPD decrements HL. Edit: but it might work if I used JP...
by hoglet
Tue Aug 14, 2018 1:56 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

And here's a greatly improved version that only has one loop, and uses IX as the counter. It works by decrementing MEMPTR until bit 13 is seen to change state, which is much simpler. This works out bits 12..0, and we can just OR-in bit 13 at the end. So it ends up being faster as well. 10 code%=&E00...
by hoglet
Tue Aug 14, 2018 1:00 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

For a bit of fun, I've written a program to work out the current value of the hidden Z80 MEMPTR register. I've read that Boo-boo and Vladimir Kladov, who made the final MEMPTR discoveries in 2006, had such a program. But I've not seen it posted anywhere. Here's a few notes to go along with it: - the...
by hoglet
Tue Aug 14, 2018 7:27 am
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Hi Tony, Yes, indeed an interesting idea and thought-provoking idea. Am I right in thinking the main advantage over any existing software approach is the ability to gain some insights into the operation of an instruction machine cycle by machine cycle? My approach to testing the Z80 Protocol Decoder...
by hoglet
Mon Aug 13, 2018 6:32 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

TonyB wrote:
Mon Aug 13, 2018 6:28 pm
How much free space does the ROM have?
Here's a disassembly:
https://acorn.huininga.nl/pub/docs/sour ... 80_120.asm

There is an obvious block from F069-F1D3 that could be re-purposed.

Dave
by hoglet
Mon Aug 13, 2018 5:50 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

This still leaves IM 0, which could be used with a little bit of circuitry. The best opcode to put on the data bus during the interrupt acknowledge cycle is E9H for JP (HL) as this does not modify WZ, according to the doc. Incidentally, this is a good example of why the instruction mnemonic should ...
by hoglet
Mon Aug 13, 2018 5:41 am
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

So this implies MEMPTR is involved during cycle 17-21 when the PC is decremented, but not elsewhere. Would you know if it was used before that? Surely the flags are only available to inspect at the end of the instruction so only the last use of MEMPTR within an instruction is visible. The documenta...
by hoglet
Mon Aug 13, 2018 5:36 am
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Tony, Re MEMPTR, I mean validating just the LDIR behaviour in the document, if possible. I think the tricky bit is making sure WZ is not used between the interrupted LDIR and BIT x,(HL), which rules out IM 2. It sounds like you have better documentation about MEMPTR than I have. The document I have ...
by hoglet
Sun Aug 12, 2018 10:14 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

I got a bit lost on the thread as so many others to follow, but my rc2014 was a Zilog Z84C0010PEG z80 if anyone needs me to check anything. If already have one of those for testing then it lets me off the hook! Mostly of the last few days has been a deep dive into some of the undocumented aspects o...
by hoglet
Sun Aug 12, 2018 9:43 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

[Thanks for the info. Perhaps you could check MEMPTR too, on a Zilog Z80? The tests so far on the Z80 Co Pro have used a SGS Z8400BB1 Z80B CPU (6MHz) datecode 88346. When you say check MEMPTR, what do you mean exactly? i.e. Attempt to validate the info in that document, or something more specific?
by hoglet
Sun Aug 12, 2018 9:15 pm
Forum: acorn atom
Topic: ICE T65/Z80/6809
Replies: 644
Views: 44738

Re: ICE T65/Z80/6809

Elminster wrote:
Sun Aug 12, 2018 9:09 pm
Ah that would be useful. Is it missing from the wiki manual? I can’t see anything about s-record or ‘srec’
Ah yes, I think the manual pre-dates it. Easily fixed.
by hoglet
Sun Aug 12, 2018 9:13 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Apologies for the insulting question, but did you test LDIR at address xxFE or xxFF? Not insulting at all! After all, I'm pretty new to the Z80. Yes, earlier today BigEd ran the test and adjusted code% so that the LDIR fell at: &9FFD, &9FFE, &9FFF and &A000 in turn. At &9FFD, &9FFE, &9FFF, f5/f3 we...
by hoglet
Sun Aug 12, 2018 8:52 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

What is the source of the WZ info? This document by Vladimir Kladov: https://gist.github.com/drhelius/8497817 MEMPTR, esoteric register of the ZiLOG Z80 CPU. by Boo-boo (first and draft English translation by Vladimir Kladov) As it is known, after the instruction BIT n,(HL) execution, bits 3 and 5 ...
by hoglet
Sun Aug 12, 2018 8:18 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

Unfortunately I can't access github nowadays due to authentication errors as I use an old PC. Are the links just to C code or is there more discussion there? Yes, it's just the C code for the Z80 Logic Analyzer Capture decoder that I'm working on. What you have found is new information. =D> I imagi...
by hoglet
Sun Aug 12, 2018 6:32 pm
Forum: acorn atom
Topic: ICE T65/Z80/6809
Replies: 644
Views: 44738

Re: ICE T65/Z80/6809

So I have been playing with ice-t on Beeb with video issue, and though it could be useful if you could dump an entire program into memory. I don’t think you can do that other than a lot of W commands. My idea was you could write a program on an emulator. Dump the memory to a file with something lik...
by hoglet
Sun Aug 12, 2018 6:27 pm
Forum: hardware
Topic: Z80 Protocol Decoder
Replies: 159
Views: 2460

Re: Z80 Protocol Decoder

I think it would be less confusing to call bits 5 and 3 of the flags YF and XF consistently when talking about them individually. In your logs you mix letters and numbers after F = and I suggest displaying Y and X if they are 1 and spaces if they are 0, to be consistent with the other flags. Yes, I...
by hoglet
Sat Aug 11, 2018 8:44 am
Forum: acorn atom
Topic: Atomulator Keyboard
Replies: 3
Views: 104

Re: Atomulator Keyboard

Greyheart wrote:
Sat Aug 11, 2018 8:29 am
I ask because I can't find a PC key that gives me an asterix (*) on the Atom. I get a ( bracket if I press shift 8.
On my laptop it's it's the key two to the right of L, shifted, which is marked with an @.

You can refined the keys if you like.

Dave
by hoglet
Thu Aug 09, 2018 5:36 pm
Forum: software: new games
Topic: New Release: Retro Software's WHITE LIGHT by Sarah Walker
Replies: 91
Views: 6654

Re: New Release: Retro Software's WHITE LIGHT by Sarah Walker

leenew wrote:
Thu Aug 09, 2018 5:27 pm
Move along.... nothing to see here... :- :-
The earlier reported issues affecting MMFS, and in fact any filing system in writable sideways RAM, do still stand.
by hoglet
Thu Aug 09, 2018 9:43 am
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 257
Views: 9338

Re: RGB to HDMI using a Pi Zero and a small CPLD

Hi Guys, Thanks for the interest, but I just want to make it clear that I'm not planning to produce any more built-up boards, at least not in the near future. It took me the best part of a week, working 8-10 hours a day, to produce the previous 10, when you include all the time for component orderin...