Search found 1333 matches

by Coeus
Sat Sep 14, 2019 9:43 pm
Forum: emulators
Topic: b-em - bug or misunderstanding
Replies: 10
Views: 406

Re: b-em - bug or misunderstanding

[pc=329] Writing outside of RAM @ ECD664 = 00 That's interesting as I have just been trying to work out my Master with MOS 3.52 b-em configuration would crash with a similar error message and yet the MOS 3.50 didn't. Likewise with 3.22 and 3.20. These are patched versions for Y2K and various bugs. ...
by Coeus
Fri Sep 13, 2019 6:57 pm
Forum: emulators
Topic: b-em PDP11 tube processor
Replies: 7
Views: 204

Re: b-em PDP11 tube processor

Coeus wrote:
Fri Sep 13, 2019 3:39 pm
It also leaves me wondering how this language priority mechanism works.
So it works by using a service call to retrospectively update the OSes cached ROM type byte to disable languages that are not for the correct processor.

That's quite clever.
by Coeus
Fri Sep 13, 2019 3:39 pm
Forum: emulators
Topic: b-em PDP11 tube processor
Replies: 7
Views: 204

Re: b-em PDP11 tube processor

*Actually, generic code that can be used with any language ROM. link , source Ok, having your PDP11 BASIC ROM loaded does seem to salvage the situation in that now PDP11 BASIC gets transferred instead and the PDP11 is quite happy to run that. That doesn't address the case where you are happy to dro...
by Coeus
Fri Sep 13, 2019 3:03 pm
Forum: emulators
Topic: b-em PDP11 tube processor
Replies: 7
Views: 204

Re: b-em PDP11 tube processor

Same thing happens on the 6502 if you load over &00F0-&00FF. The 6502 Client doesn't do anything to stop you the user trashing the system. The whole Acorn philosophy is that it is ***YOUR*** responsibility what **YOU** do to **YOUR** system. But the issue here is it is not me sat at the keyboard do...
by Coeus
Fri Sep 13, 2019 1:26 am
Forum: emulators
Topic: b-em PDP11 tube processor
Replies: 7
Views: 204

b-em PDP11 tube processor

Cribbed from the PiTubeDirect project, I now have a branch of b-em with a PDP11 co-processor: pdp.png https://github.com/stardot/b-em/tree/sf/pdp11 I did come across a couple of interesting things along the way. 1. The routine loop0 in the PDP11 core (pdp11.c) would execute as long as tubeContinueRu...
by Coeus
Wed Sep 11, 2019 12:25 am
Forum: hardware
Topic: Hmm.. was there ever an 8" floppy drive for the BBC?
Replies: 37
Views: 917

Re: Hmm.. was there ever an 8" floppy drive for the BBC?

gtoal wrote:
Tue Sep 10, 2019 6:52 pm
I guess I could do that, but I have several hundred images to unpack and was waiting until I could find a command line program that I could script to do them all at once rather than each one manually through a GUI :-/
Check out SWH's beeb perl script: https://www.spuddy.org/Beeb/mmb_utils.html
by Coeus
Tue Sep 10, 2019 12:36 am
Forum: emulators
Topic: b-em - bug or misunderstanding
Replies: 10
Views: 406

Re: b-em - bug or misunderstanding

I did discover a bug in the latest master where the 32016 would not give the Pandora prompt which was due to failing to set the clock speed of the 32016 fast enough. I have fixed that and pushed the fix to master on GitHub. As for the case where cat :1 does not do as expected, this does seem to be f...
by Coeus
Sun Sep 08, 2019 7:13 pm
Forum: emulators
Topic: b-em - bug or misunderstanding
Replies: 10
Views: 406

Re: b-em - bug or misunderstanding

When firing up Panos, I loaded the welcome disc in drive 1 leaving the start up disc in drive 0. It wouldn't load the welcome program, and when I did a cat :0 and :1, the disc catalogue is the same. I had a look at the disc images, and they look correct. This appears to be a Panos thing. I get the ...
by Coeus
Sat Sep 07, 2019 2:09 pm
Forum: emulators
Topic: b-em - bug or misunderstanding
Replies: 10
Views: 406

Re: b-em - bug or misunderstanding

I can't work out how to load a hard disc image, or indeed if you can't load one, where it expects to find one (I am on Arch Linux) The supplied ROMs all assume SCSI hard discs as per the original winchester so you would need SCSI hard discs enabled from the Disc menu then on Linux It looks in ~/.co...
by Coeus
Thu Sep 05, 2019 3:22 pm
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

So when it comes to fixing this on an emulator that also emulates a Master it is necessary to know what the master does. As far as I know the address decoding on the master is done by a PAL so we can't work it out from the circuit diagram. Fortunately my master is vanilla, at least in this respect s...
by Coeus
Thu Sep 05, 2019 11:43 am
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

This is not true for some of the BITD ROM/RAM boards which defined extra registers. Solidisk 4MEG 256KB to name but one. Their basic SWRAM module with, I think 32K, had some flying leads which you could attach to any latch you liked. Those controlled which bank was selected for writing which need n...
by Coeus
Wed Sep 04, 2019 10:54 pm
Forum: archive submissions
Topic: ROMs from Graham Toal
Replies: 4
Views: 370

Re: ROMs from Graham Toal

Another piece of software I've subsequently found (but haven't yet extracted from the floppy disk image) is a patch to a specific dfs+nfs rom, which tweaks it to support 77 track 8in disks! I suspect there are not many of those drives left around, I've certainly lost mine. If I remember rightly, th...
by Coeus
Wed Sep 04, 2019 10:27 pm
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

I am not sure if it informs the discussion in any way but I have been looking further afield in the address decoding. Here's a larger part of the circuit diagram: decode.png Starting with IC22 at the top this is testing for all the address lines A15-A10 being 1 so this is checking for an address of ...
by Coeus
Wed Sep 04, 2019 10:06 pm
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

I'm pretty sure b2 gets the video ULA and CRTC wrong (which I must fix!), and I'll now have to check it's doing ROMSEL correctly too... B-Em looks like it has this wrong for ROMSEL at least. To a first approximation where the master decodes the addresses more fully b-em seems does the same and then...
by Coeus
Wed Sep 04, 2019 9:54 pm
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

Following on from that, looking at the other 2-4 line decoder it looks like the BBC AUG may be wrong about the serial ULA. It has a table: 00-07 6845 CRTC 08-0F 6840 ACIA 10-1F Serial ULA 20-2F Video ULA 30-3F ROM select ... It looks from the circuit diagram that the serial ULA is only addressable a...
by Coeus
Wed Sep 04, 2019 9:47 pm
Forum: emulators
Topic: BBC B hardware mapping extent -- quick tests!
Replies: 15
Views: 361

Re: BBC B hardware mapping extent -- quick tests!

I looked at this but I don't think there is much point in me running the test for the rom select latch as I have some sideways RAM/ROM modules that use bus snooping and my BASIC ROM is on one of those. Hopefully we will here from someone with a vanilla machine soon but in the meantime I thought I'd ...
by Coeus
Mon Sep 02, 2019 12:10 pm
Forum: hardware
Topic: Spooling cats and Datacentres
Replies: 11
Views: 425

Re: Spooling cats and Datacentres

RAMFS is based on DFS 0.90, and DFS turns off SPOOL output when displaying any output. You can bypass it by hooking into BYTEV and intercepting the OSBYTE calls. I think there was a thread on here about it some years ago, but I can;t work out the search terms to find it. Presumably DFS is not re-en...
by Coeus
Sat Aug 31, 2019 11:16 pm
Forum: hardware
Topic: Hmm.. was there ever an 8" floppy drive for the BBC?
Replies: 37
Views: 917

Re: Hmm.. was there ever an 8" floppy drive for the BBC?

Winchester hard drives of the era I believe were the same in that they ran continuously while powered. I wonder why that changed. I could take a guess. Hard discs should be fairly low friction. While I believe floppies are made to keep the friction down one can feel a little resistance so I suspect...
by Coeus
Sat Aug 31, 2019 10:30 am
Forum: hardware
Topic: Hmm.. was there ever an 8" floppy drive for the BBC?
Replies: 37
Views: 917

Re: Hmm.. was there ever an 8" floppy drive for the BBC?

I have never seen any. The diffences between the two shugart standards don't seem to be that dramatic and the 8271 dates from the 8" era so I suspect it may just be a case of making up the correct cable.

There is more info at: http://www.hermannseib.com/english/synt ... floppy.htm
by Coeus
Sun Aug 25, 2019 3:23 pm
Forum: software: other
Topic: Tube host code ROMs
Replies: 3
Views: 186

Re: Tube host code ROMs

Exmon II is popular, at least for those who want to debug assembler code on the BBC micro, and that has plenty of spare space at the end. You may be able to patch the tube host code into there and daisy chain the service call handler which is pretty much what Acorn did when they put it into the DFS ...
by Coeus
Fri Aug 23, 2019 8:59 pm
Forum: emulators
Topic: Emulation tests
Replies: 13
Views: 539

Re: Emulation tests

I have been away so I am late to the party on this one. I assume part of the intention here is that this could be automated to the extent of having being able to issue a single command on the host OS and run a bunch of tests? One approach which would work easily on the current B-Em would be to scrip...
by Coeus
Fri Aug 16, 2019 8:30 am
Forum: hardware
Topic: ADFS Upgrade board repair
Replies: 9
Views: 280

Re: ADFS Upgrade board repair

does not look like a Acorn one, as the 1770 is in a socket, unless it's been fixed previously... I reckoned Acorn based on two chips on the underneath of the board which was very similar to the picture of a known Acorn board. All the other pictures I could seee had all the chips on the top. Having ...
by Coeus
Thu Aug 15, 2019 7:14 pm
Forum: hardware
Topic: ADFS Upgrade board repair
Replies: 9
Views: 280

Re: ADFS Upgrade board repair

You also asked: Can any one identify the exact type of upgrade and manufacturer...I’ve just bought this beeb. Not 100% but it looks more like the Acorn than the others. Acorn board at: http://8bs.com/see/acorn1770.jpg There are pictures of several of the 1770 boards at: http://8bs.com/seeboards.htm
by Coeus
Thu Aug 15, 2019 3:56 pm
Forum: hardware
Topic: ADFS Upgrade board repair
Replies: 9
Views: 280

Re: ADFS Upgrade board repair

Also the DFS chip above the board, is this correct for a bbc b or is it for a bbc b+ . Originally a BBC model B would have had an i8271 and associated DFS. This was an old chip even when the upgrade was first released, dating from the 8" era, and soon became expensive. Various independent disc upgr...
by Coeus
Thu Aug 15, 2019 1:36 am
Forum: hardware
Topic: IFEL Acorn Master Switcher (Master switchable OS)
Replies: 3
Views: 178

Re: IFEL Acorn Master Switcher (Master switchable OS)

Thanks. So with a 512Kx8 EPROM the selection is a straightforward binary code on the A and B headers. I assume GND is probably pin on each so the three wires to the switch means the switch can close either A or B or leave them both open but not close both. I am sure how you'd get a switch to do more...
by Coeus
Thu Aug 15, 2019 1:19 am
Forum: hardware
Topic: what's the use of Mode 0
Replies: 24
Views: 906

Re: what's the use of Mode 0

If you have a BBC B (or Master) with a dual floppy drive and a second processor, then that is equivalent to some business computers that Acorn produced. See Acorn Business Computer and Acorn Cambridge Workstation ... I suppose with a long-term plan based on 2nd processors and, according to Steve Fu...
by Coeus
Thu Aug 15, 2019 1:12 am
Forum: hardware
Topic: IFEL Acorn Master Switcher (Master switchable OS)
Replies: 3
Views: 178

IFEL Acorn Master Switcher (Master switchable OS)

This is mentioned on the retro hardware list but does not appear in Steve's ebay shop. I got one already fitted to a Master I bough and I notice it has three two pin headers on one edge. Three pins of these, two from one header and one from the centre one, are connected to what is presumably a SPDT ...
by Coeus
Tue Aug 13, 2019 9:30 pm
Forum: hardware
Topic: MMC hard drive emulation?
Replies: 326
Views: 22856

Re: MMC hard drive emulation?

Is possible that you have complete rom images for the patched MOS 3.20 and the unpatched MOS 3.50 ?. So i can burn them to eproms i can piggyback a second eprom on top and build a selector. So this is what I have the the machine for the MOS 3.20 and MOS 3.50 banks. The MOS 3.20 contains, as well as...
by Coeus
Tue Aug 13, 2019 5:15 pm
Forum: hardware
Topic: MMC hard drive emulation?
Replies: 326
Views: 22856

Re: MMC hard drive emulation?

Am I right in thinking the SD-enabled version can't access floppies? Just worth bearing in mind if you're actually going to swap it for the version in the megarom... Yes, at the moment I could work around this by switching to MOS 3.50 which still has an unpatched ADFS, though obviously not to trans...
by Coeus
Tue Aug 13, 2019 5:14 pm
Forum: hardware
Topic: MMC hard drive emulation?
Replies: 326
Views: 22856

Re: MMC hard drive emulation?

Another question about the ROM i tested it on the sideways ROM slot and work great :D. Have seen that is very easy to build an adapter to replace the MegaROM for a 27c010 EPROM. Is possible to replace the ADFS on the megarom for this modified version ?. I have done that, in a sense. I have one of t...