Search found 1111 matches

by dominicbeesley
Fri Sep 18, 2020 4:51 pm
Forum: acorn atom and acorn system series
Topic: System 5 / 6502A cpu card - questions
Replies: 5
Views: 144

Re: System 5 / 6502A cpu card - questions

Thanks Mark and Thanks Dave, I'd not spotted that thread but I had spotted the pin 19 errors elsewhere.

I'm still puzzled by the IC12 direction thing, especially as there's free LS86 which could have been used to invert R/W when NBGT is asserted.

D
by dominicbeesley
Fri Sep 18, 2020 11:17 am
Forum: acorn atom and acorn system series
Topic: System 5 / 6502A cpu card - questions
Replies: 5
Views: 144

Re: System 5 / 6502A cpu card - questions

Moderators, i just realised I have managed to post this in the wrong forum. Is there a way to move the thread to the Atom/system forum please?

D
by dominicbeesley
Thu Sep 17, 2020 3:11 pm
Forum: acorn atom and acorn system series
Topic: System 5 / 6502A cpu card - questions
Replies: 5
Views: 144

Re: System 5 / 6502A cpu card - questions

Supplementary questions: IC12 is normally disabled when a local resource (VIA, onboard RAM/ROM) is being accessed but the sense is flipped during a DMA access (when NBGT is asserted) but the sense of DIR to the buffer isn't - so won't this be the wrong way round for the DMA device? Would it be worth...
by dominicbeesley
Thu Sep 17, 2020 12:30 pm
Forum: acorn atom and acorn system series
Topic: System 5 / 6502A cpu card - questions
Replies: 5
Views: 144

System 5 / 6502A cpu card - questions

Hello, I've decided to slow start on transcribing the System 5 6502A cpu card into Kicad with a view to getting some PCBs made. I've been poring over the diagram this morning and have some (probably naive) questions - I have no experience of the System series other than a few VHDL experiments - so p...
by dominicbeesley
Tue Sep 15, 2020 11:20 am
Forum: 8-bit acorn software: classic games
Topic: BBC Elite source, now fully documented and explained
Replies: 73
Views: 2458

Re: BBC Elite source, now fully documented and explained

I seem to recall that when playing BITD... most disappointing
by dominicbeesley
Sun Sep 13, 2020 5:38 pm
Forum: 8-bit acorn software: other
Topic: HOSTFS and !BOOT
Replies: 5
Views: 222

Re: HOSTFS and !BOOT

Thanks - I'll remember that one

D
by dominicbeesley
Sat Sep 12, 2020 4:30 pm
Forum: 8-bit acorn software: other
Topic: HOSTFS and !BOOT
Replies: 5
Views: 222

Re: HOSTFS and !BOOT

Well, I rebuilt the rom and it seems to be working now - I think the old build must have had something up with the defines. I (got decode6502 working and) discovered that it was never hitting the boot check code!

Thanks for the moral support and pointers

D
by dominicbeesley
Sat Sep 12, 2020 2:03 pm
Forum: 8-bit acorn software: other
Topic: HOSTFS and !BOOT
Replies: 5
Views: 222

Re: HOSTFS and !BOOT

Thanks Dave. Yes it's getting on there and returning what look to be the correct bytes FF 12 03. I tried swapping X and Y but still no joy. It's not easy for me to debug the boot sequence atm but i can try sticking something in the ROM or get NoIce working again but I have managed to break the seria...
by dominicbeesley
Sat Sep 12, 2020 1:07 pm
Forum: 8-bit acorn software: other
Topic: HOSTFS and !BOOT
Replies: 5
Views: 222

HOSTFS and !BOOT

Hello, I'd be grateful if I could get some advice on what to do to get HostFS to do shift-break. I've been using a hacked version of HostFS rom on my beeb (a version that has been hacked for UPURSFS and then hacked by me to work with Myelin's sd card/serial adaptor) for the server I'm using Sweh's p...
by dominicbeesley
Tue Sep 08, 2020 10:06 am
Forum: 8-bit acorn hardware
Topic: A blitter for the beeb?
Replies: 132
Views: 16604

Re: A blitter for the beeb?

Thanks Nigel, do let me know if there's anything you'd like me to look at

D
by dominicbeesley
Mon Sep 07, 2020 11:17 pm
Forum: 8-bit acorn hardware
Topic: A blitter for the beeb?
Replies: 132
Views: 16604

Re: A blitter for the beeb?

Here's another update on developments. I've spent some time recently on the support software to allow the sound facilities to be used from BASIC with a handful of *commands to load samples that can then be played using SOUND/ENVELOPE as normal. I'm putting together a talk for the December Abug "musi...
by dominicbeesley
Mon Sep 07, 2020 11:28 am
Forum: 8-bit acorn software: other
Topic: MOS ROM information / guids
Replies: 27
Views: 4244

Re: MOS ROM information / guids

I've made a few changes to Alnitak's sources - mainly around the SOUND/ENVELOPE processing where the labelling had got confused (labels were mis-applied 4 bytes out due to the index X begin 4..7 rather than 0..3!). This had me going for a while when porting to the 6809 and doing the rom for the Blit...
by dominicbeesley
Fri Sep 04, 2020 1:14 pm
Forum: 8-bit acorn software: classic games
Topic: BBC Elite source, now fully documented and explained
Replies: 73
Views: 2458

Re: BBC Elite source, now fully documented and explained

Thanks both, I'll try and get a look at this in the next week or so - I'll probably stick with the tape version for my initial experiments but I'm hoping to get the Blitter's line drawing acceleration poked in - it looks like it _should_ be straightforward as the line drawing code is pretty clear, a...
by dominicbeesley
Fri Sep 04, 2020 10:43 am
Forum: 8-bit acorn software: classic games
Topic: BBC Elite source, now fully documented and explained
Replies: 73
Views: 2458

Re: BBC Elite source, now fully documented and explained

How different are the tape / disk variants? Is it likely possible to get them into a single source with IF/DEFs to build the variants or are they just too different - I speak from a position of ignorance, I don't really know the differences that well but I'd like to do some hacking...

D
by dominicbeesley
Fri Sep 04, 2020 10:37 am
Forum: programming
Topic: The NMI is (almost) a lie!
Replies: 2
Views: 231

Re: The NMI is (almost) a lie!

That is interesting.
by dominicbeesley
Tue Sep 01, 2020 10:30 pm
Forum: 8-bit acorn hardware
Topic: BBC B+/Master graphics upgrade?
Replies: 28
Views: 1135

Re: BBC B+/Master graphics upgrade?

As others have said this is a non-trivial exercise on existing hardware as it is really set up to give 2MHz of memory bandwidth to the CPU and the other two to the video system. On my list of ideas for experiments would be to hack together something like Rob's NULA but with some extra features: In "...
by dominicbeesley
Mon Aug 31, 2020 11:45 am
Forum: programming
Topic: A new BBC Micro MOS Reassembly
Replies: 32
Views: 1395

Re: A new BBC Micro MOS Reassembly

This looks excellent! Brilliant work -- I've been using the raybellis version from GitHub lately but this looks even better. I have some requests though: - is it possible to produce a version with original addresses embedded? - useful when stepping through in the debugger - is there a version compat...
by dominicbeesley
Fri Aug 28, 2020 4:32 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

I'm not sure, I can't admit to a thorough review of this it was just a vague memory of either something I read somewhere or something I once tripped over already. I suspect it's only the undocumented instructions that would read the databus during a write cycle but you never know! [My experience wou...
by dominicbeesley
Fri Aug 28, 2020 3:10 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

I am a ***ing idiot! I'd forgotten that t65 needs DO feeding back to DI during write cycles! This was causing the ASO instruction to read back the un-shifted value from DI instead of what was being written back! I'm sure this has bitten me before in the dim and distant! Thanks for the confirmation t...
by dominicbeesley
Fri Aug 28, 2020 1:28 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

Here you go. It would be good to get a sanity check. I'm now assuming this is some timing problem. I'd thought that the interface signals were all registered (which seems in general to be the case) but I wonder if some of the changes for illegal instructions are combinatorial and breaking my timing?...
by dominicbeesley
Fri Aug 28, 2020 12:38 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

Mmm, 313 is giving the same vertical blinds thing as the 315 version. I will investigate further
by dominicbeesley
Thu Aug 27, 2020 5:27 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

Mmm, a real poser. I've got the whole thing in bits now doing something else but if I get a chance this evening I'll try rolling back to that earlier version and see if things are ok though I think my "314" version was the version from AtomBusMon with my own qucik'n'dirty body to allow RDY to work c...
by dominicbeesley
Thu Aug 27, 2020 1:46 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

I've given the 315 version a go. It's certainly an improvement but still not quite right. There's a "vertical blinds" effect on some of the sprites. https://www.youtube.com/v/A6TSf1SJOlo&hl=en&fs=1 Does anyone have any idea which illegal op is being missed here. I'm guessing from RTW's post here tha...
by dominicbeesley
Thu Aug 27, 2020 10:45 am
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

Thanks Dave

Accuracy is my main aim... I'll try the 315 t65 core and see how i get on. I'll report back hopefully later today
by dominicbeesley
Wed Aug 26, 2020 10:52 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

Re: t65 core latest version with illegal instructions

Cool, thanks! I'll give that a go tomorrow when I'm feeling a bit better (hopefully - been laid low by the covid). I originally looked at Mist but somehow seem to have missed the 315 stuff which looks like it might have some undoc instruction fixes, I'll have to do some regression testing! I'll repo...
by dominicbeesley
Wed Aug 26, 2020 3:50 pm
Forum: 8-bit acorn hardware
Topic: t65 core latest version with illegal instructions
Replies: 14
Views: 430

t65 core latest version with illegal instructions

Hello, I've not updated my t65 core for some time and I'm wondering where the place to get the latest is? I used to follow it at fpga arcade but the svn is now dead. Where's the latest/best version? If there isn't one I'll have to have a delve! Most things work ok but Zalaga is still not quite right...
by dominicbeesley
Thu Aug 20, 2020 10:21 pm
Forum: 8-bit acorn hardware
Topic: Allocating addresses in FExx (SHEILA)
Replies: 4
Views: 250

Re: Allocating addresses in FExx (SHEILA)

I've used a few in the fe3x block for memory control in my blitter board but I'm planning to move them elsewhere to avoid as many compatibility concerns as possible.

Go to advanced search