Search found 2692 matches

by BigEd
Thu Dec 12, 2019 3:39 pm
Forum: for sale / freebies
Topic: New Finds from the Attic/Workshop - Taken : But now more
Replies: 5
Views: 238

Re: New Finds from the Attic/Workshop - Taken

There was a lovely emulator...
http://web.archive.org/web/201105181223 ... 6_s3a.html
Perhaps see also
http://cd.textfiles.com/230/EMULATOR/PSION/
or just search for [s3aemul psion emulator]
by BigEd
Wed Dec 11, 2019 12:04 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Might be worth noting that we're a bit surprised at how much state there is in the implementation (as seen in the ebay photos) compared to our expectations. It would still be very interesting to know more about the system -photos of both sides of the PCB at high resolution might give us some useful ...
by BigEd
Wed Dec 11, 2019 10:10 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Also worth noting, we realised that with a page-aligned base pointer of (zp),Y accesses there's no issue with in-bank wrapping. This should be readily arranged - we think we can see a way one might build a large-model Life for example, with one huge datastructure spanning as many banks as needed (bu...
by BigEd
Sat Dec 07, 2019 2:07 pm
Forum: general
Topic: Remarkable videos recently posted on Youtube
Replies: 297
Views: 34918

Re: Remarkable videos recently posted on Youtube

"SUPER MENU!" In the year 6502AD... ... here's a great 30min presentation on a great work, the construction of a plug-compatible homebrew 6502 CPU in TTL devices. For Drass, the presenter and chief designer, it was the first hardware, first PCB, first soldering - and it worked! At 20MHz! Mostly surf...
by BigEd
Thu Dec 05, 2019 9:44 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

That's a great use of 3 (or 4) banks! I imagine the ARM simulators were run on these turbo boxes. It would be interesting indeed if BAS128 could be a useful starting point to construct a TurboBasic.
by BigEd
Thu Dec 05, 2019 12:30 pm
Forum: hardware
Topic: 6502 Assembly on BBC B, what do I need?
Replies: 21
Views: 623

Re: 6502 Assembly on BBC B, what do I need?

I've relatively often used a Beeb headless - there's just a couple of things to type in blindly at boot which redirects input from the serial port. Once that's done, you can type at the command line over serial, including setting up the redirection of output to the serial port. Here are my notes, wh...
by BigEd
Thu Dec 05, 2019 10:03 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

(Don't worry about RDY and write cycles - that's only a problem with the NMOS 6502, and here we're talking about a CMOS part.) Indeed, it might take an extra cycle for the carry. There is a little time available though, if the affected address bits are the second to be presented, in the CAS part of ...
by BigEd
Thu Dec 05, 2019 9:59 am
Forum: hardware
Topic: 6502 Assembly on BBC B, what do I need?
Replies: 21
Views: 623

Re: 6502 Assembly on BBC B, what do I need?

If you want to use a CRT for retro authenticity, look for a TAXAN or KAGA 12" green-screen monitor, that's really clear.

But an LCD display, driven preferably from the RGB out, should be pretty clear.
by BigEd
Thu Dec 05, 2019 9:17 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Yes, it could that the second mux is unused. Dave's experiments with 65ARTHURT do seem to show that there's no effort to carry into the third byte, so I should stop looking for evidence... ... and yet, I realised this morning that I was wrong to think comparisons against FF and 00 are needed. It's e...
by BigEd
Wed Dec 04, 2019 10:46 pm
Forum: hardware
Topic: Raspberry Pi inside BBC Master (not a second processor)
Replies: 10
Views: 332

Re: Raspberry Pi inside BBC Master (not a second processor)

I think you do need to make a different kind of connection. Unless there's a way to get the GPU to do enough of what's needed while Linux is running on the ARM (the GPU is needed for the bitbanging because there are very tight deadlines.)
by BigEd
Wed Dec 04, 2019 10:07 pm
Forum: hardware
Topic: Raspberry Pi inside BBC Master (not a second processor)
Replies: 10
Views: 332

Re: Raspberry Pi inside BBC Master (not a second processor)

The thing about a second processor is that it's captive: all I/O goes to the host, which is a Beeb or Master. This thread is about how to access the I/O that the Pi has: audio, video, network, storage, GPIO - from the user's position on the host. Normally you'd find a Pi is running Linux which has d...
by BigEd
Wed Dec 04, 2019 6:36 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

(Not to steal Dave's thunder, but he reports that 65ARTHURT, the emulator posted upthread by awilliams, and the best reference we have for the behaviour of the Extended second processor, does indeed wrap within 64k banks - this is not a flat memory model!)
by BigEd
Wed Dec 04, 2019 6:11 pm
Forum: projects
Topic: B-em and BeebEm N flag in BCD
Replies: 16
Views: 311

Re: B-em and BeebEm N flag in BCD

Just a little further down the document:
On the 6502, only the C flag is valid. The 65C02 and 65816 datasheets state that the N, V, and Z flags are valid as well as the C flag
It's best to read the whole thing, especially as the final section is an errata section!
by BigEd
Wed Dec 04, 2019 5:54 pm
Forum: projects
Topic: B-em and BeebEm N flag in BCD
Replies: 16
Views: 311

Re: B-em and BeebEm N flag in BCD

(There's a very thorough treatment by Bruce Clark here.)
by BigEd
Wed Dec 04, 2019 2:15 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Indeed, it could well be that the mux is for RAS and CAS multiplexing. Although, why a dual 4 way mux? It would be good if we can get more information about the device - it's possible the seller, when they receive the box, will check in here or somewhere and help to answer some questions. If anyone ...
by BigEd
Wed Dec 04, 2019 1:39 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

An interesting idea. We don't know exactly how this box is built, but we do know that three-byte addressing carries a small performance penalty, so I very much expect to see RDY brought into play to stall the affected instructions at least for one cycle. It might be argued that the cycle-by-cycle be...
by BigEd
Wed Dec 04, 2019 8:35 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

What might a dual 4-way mux be useful for? It just might be useful for selecting the top two address bits: zero because non-turbo mode, zero because not a special cycle of a special opcode, bit from page 3, inverse of bit from page 3... If indeed the memory is flat not banked, I think we'd need to s...
by BigEd
Tue Dec 03, 2019 9:28 pm
Forum: hardware
Topic: Raspberry Pi inside BBC Master (not a second processor)
Replies: 10
Views: 332

Re: Raspberry Pi inside BBC Master (not a second processor)

To do that today, you'd probably connect with the serial port and stick to text-mode use of the Pi. Then your Beeb is a dumb terminal, or a slightly smart terminal. You should be able to edit files, browse the web, run makefiles and develop software, just like it's the mid-80s. PiTubeDirect isn't mu...
by BigEd
Tue Dec 03, 2019 8:28 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Good info collection Dave!

To correct a previous idea of mine, it seems both the extended and the regular machine have -15 DRAMs, so that's no difference.
by BigEd
Tue Dec 03, 2019 10:09 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Hmm, I just thought of a wrinkle, which makes the implementation in TTL a little more complex than I'd supposed. As the box aims to provide 2 MSBs to the address bus in the case of an indirect indexed access, there's the possibility of a carry from the 8 bit Y index all the way into the 2 extra bits...
by BigEd
Mon Dec 02, 2019 5:36 pm
Forum: hardware
Topic: 6502 Assembly on BBC B, what do I need?
Replies: 21
Views: 623

Re: 6502 Assembly on BBC B, what do I need?

Welcome! I suspect MMC solutions are most popular, but I've used a serial link in the past to good effect. You will find, I think, that the Beeb has a rather sophisticated OS: you are more likely to be making system calls than poking locations in memory. (The obvious exception being updating video m...
by BigEd
Mon Dec 02, 2019 2:26 pm
Forum: off-topic
Topic: Seeking 290 programs for Sinclair Cambridge Programmable
Replies: 5
Views: 864

Re: Seeking 290 programs for Sinclair Cambridge Programmable

Oh look, someone else bought a copy, and scanned and uploaded it:
https://archive.org/details/sinclair-ca ... y/page/n15

It's a Dave B - thanks Dave B - but not the Dave B you might be thinking of.
by BigEd
Sun Dec 01, 2019 4:40 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Fantastic!

(No reason presumably why we couldn't go all the way up to 16MByte as an option?)
by BigEd
Sun Dec 01, 2019 10:00 am
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

Ah yes, CMOS Basic makes sense.

Is the embedded 4.30 exactly as per normal or an interesting variation?
by BigEd
Sat Nov 30, 2019 7:03 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 24 to 26 January 2020 (Hampshire) BOOKING THREAD
Replies: 41
Views: 1518

Re: ABUG SOUTH 24 to 26 January 2020 (Hampshire) BOOKING THREAD

At these prices please put me down for the whole weekend too !
by BigEd
Sat Nov 30, 2019 7:01 pm
Forum: general
Topic: Philosophy of Disc Preservation
Replies: 19
Views: 479

Re: Philosophy of Disc Preservation

But the amateur historians among us want more!
by BigEd
Sat Nov 30, 2019 2:03 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

I do hope it's either one of us or the CCH. Or failing that, someone who gets the message that we'd really like a ROM dump and a good look at the back side of the PCB.

I wonder if any other unlabelled 6502 wedges might be out there hiding their secrets?
by BigEd
Fri Nov 29, 2019 3:10 pm
Forum: hardware
Topic: Info please! Acorn's in-house large-memory 6502 co-pro
Replies: 94
Views: 4058

Re: Info please! Acorn's in-house large-memory 6502 co-pro

I confess I know nothing about modules. But I'm intrigued by the possibility of running Acorn's own emulator of their own extended 6502. (As for CB, it seems to be a HiBasic4 (but not identical to the usual one.) And yet, something calling itself HiBasic4.30 is already embedded in 65ARTHURT. So, why...
by BigEd
Thu Nov 28, 2019 2:31 pm
Forum: general
Topic: Philosophy of Disc Preservation
Replies: 19
Views: 479

Re: Philosophy of Disc Preservation

(If we can image original disks, we might sometimes find interesting data in unused sectors - bits of source code, or other versions of game files, or other games from the same software house.)