Search found 1189 matches

by Coeus
Sat Apr 20, 2019 9:49 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 81
Views: 2515

Re: New ROM / RAM Expansion Board for BBC B

Is there a copy of 2.26 with the SRAM tools removed? I attach one I made just now. To explain, the DFS 2.26 ROM is actually four logical sideways ROMs, each with its own service routine, packed into the same physical ROM. These are: Some RAM size/startup message code Sideays RAM utils DFS Tubehost ...
by Coeus
Sat Apr 20, 2019 5:48 pm
Forum: hardware
Topic: BBC B+ 64k EEPROMs and SW RAM
Replies: 17
Views: 530

Re: BBC B+ 64k EEPROMs and SW RAM

[*]The BBC B+ has a number of SW RAM banks built in, so no need for any expansion to install SW RAM, unless of course you wanted more RAM banks to replace the on-board ROM banks. Surely that's only true of the 128K? I am pretty sure for the 64K the extra RAM is shadow RAM and an odd 12K that is not...
by Coeus
Sat Apr 20, 2019 4:17 pm
Forum: hardware
Topic: MMFS Development and Support
Replies: 770
Views: 52793

Re: MMFS Development and Support

Unfortunately, with these extra builds, some of the disks images are overflowing during the build process. So I'll need to think of restructuring the disks. So this isn't yet pushed back to github. Is it worth reviewing which of the builds one would be likely to load from an SSD? For example, the b...
by Coeus
Sat Apr 13, 2019 9:17 pm
Forum: programming
Topic: 6502 LDA / LDX / LDY and Zero flag
Replies: 8
Views: 255

Re: 6502 LDA / LDX / LDY and Zero flag

Yep! In any code LDx value:CPx #0 the CPx is superfluous unless you are wanting to change the carry flag. The reason why someone may write the superflous comparison is if they have come from writing Z80 (or 8080) assember. On thoese processors loads do not set the flags, On the 6502 it is not uncom...
by Coeus
Mon Apr 08, 2019 11:56 am
Forum: software & utilities for the pc, mac or unix
Topic: FWD: fs/adfs on Linux - keep or kill it?
Replies: 8
Views: 347

Re: FWD: fs/adfs on Linux - keep or kill it?

if it is a maintenance headache, would it be worth moving it from an in-kernel filesystem to a FUSE filesystem? That should decouple it from the kernel release schedule.
by Coeus
Wed Mar 20, 2019 10:45 pm
Forum: emulators
Topic: VIEW Command Mode and Edit Mode
Replies: 6
Views: 187

Re: VIEW Command Mode and Edit Mode

One further question: I have been unable to find the command which exits VIEW - I have been having to RESET BeebEm to leave the program. I presume there is an EXIT ommand or equivalent. No, there is no exit command because from the point of view the Acorn OS, VIEW is a language and at any time ther...
by Coeus
Sat Mar 16, 2019 3:52 pm
Forum: emulators
Topic: VDE in Beebem
Replies: 3
Views: 150

Re: VDE in Beebem

Not specific to BeebEm but you may find viewtopic.php?f=2&t=15355&p=208522&hilit=VDE#p208522 useful as it discusses VDE on Acorn CP/M.
by Coeus
Sat Mar 02, 2019 6:25 pm
Forum: hardware
Topic: Am I a Monster?
Replies: 22
Views: 663

Re: Am I a Monster?

Whether you consider it to be sacrilege is a personal thing, I suppose. If something has become rare and you happen to be sitting on one of the last examples then, even if it is legally yours, one might consider himself just being the custodian of it for future generations. I am sure that is the way...
by Coeus
Wed Feb 27, 2019 6:59 pm
Forum: emulators
Topic: So... I Had a crazy idea.....
Replies: 6
Views: 432

Re: So... I Had a crazy idea.....

A hybrid, where some hardware is emulated and some is real is an interesting idea. Based on how B-Em works, I think the one component where real hardware could not be substituted would be the 6502 because it is effectively the timing master for everything else. Others things may also be hard to sync...
by Coeus
Sat Feb 23, 2019 4:59 pm
Forum: off-topic
Topic: Retro upgrades, value for money, eBay & why bother?
Replies: 56
Views: 1938

Re: Retro upgrades, value for money, eBay & why bother?

Very sad that someone has shown himself to be so mean spirited. @RobC - I don't know where you fall back to in that circumstance. Presumably they got banned because of complaints from other eBayers too but for an obvious breech of eBay's own policy you'd have thought they would step in there. Presum...
by Coeus
Sat Feb 23, 2019 4:28 pm
Forum: off-topic
Topic: Retro upgrades, value for money, eBay & why bother?
Replies: 56
Views: 1938

Re: Retro upgrades, value for money, eBay & why bother?

I had to complain about one fraudster who was selling 74LSxxx very cheaply in multiple batches. I bought a load, he marked them as dispatched, then said he was out of stock and cancelled my order. In the meantime he amended the listing to reduce the quantity per item and increase the price, and car...
by Coeus
Sat Feb 23, 2019 2:56 pm
Forum: emulators
Topic: B-em on OSX with M5000 support
Replies: 14
Views: 517

Re: B-em on OSX with M5000 support

Looking into this even more, the &FE doesn't exist in real hardware and if the compiler is very good it should be optimised away . Bit 0 is the disable bit. If it is set the FREQ macro isn't used. If bit 0 is clear then the macro is use and the &FE is implied. gcc 8.2.1 is not clever enough to have...
by Coeus
Fri Feb 22, 2019 11:43 pm
Forum: emulators
Topic: B-em on OSX with M5000 support
Replies: 14
Views: 517

Re: B-em on OSX with M5000 support

I couldn't hear the difference either but, as the consensus seems to be it is a bug, I have pushed the fix to master in github.
by Coeus
Fri Feb 22, 2019 11:40 am
Forum: hardware
Topic: Sideways Ram
Replies: 23
Views: 586

Re: Sideways Ram

Glued into spare ROM space ... Where might I find Information on merging ROMs? I don't think there is an automated way to do this. The first step is to identify a ROM which has the spare space, usually inidcated by the bytes at the end of the ROM still being all FF or 00. Next, if you have the sour...
by Coeus
Mon Feb 18, 2019 11:10 am
Forum: off-topic
Topic: Retro upgrades, value for money, eBay & why bother?
Replies: 56
Views: 1938

Re: Retro upgrades, value for money, eBay & why bother?

cmorley wrote:
Mon Feb 18, 2019 7:08 am
Follow up.

I did as leenew suggested and contacted eBay customer services at the weekend (webform). I got a response from eBay this morning and they have deleted the negative feedback.
That's great news, Chris, and well-deserved.
by Coeus
Mon Feb 18, 2019 11:08 am
Forum: emulators
Topic: B-em on OSX with M5000 support
Replies: 14
Views: 517

Re: B-em on OSX with M5000 support

Thanks for your reply Coeus. I'll see what I can find. It might not make any difference anyway to the latency........I will revisit it sometime. I you remember the latency is due to the buffer size inside b-em which can be adjusted from the config file. What a different OS may do is allow this buff...
by Coeus
Wed Feb 13, 2019 8:31 pm
Forum: general
Topic: Bit of fun Part Two - CPU Swap
Replies: 28
Views: 820

Re: Bit of fun Part Two - CPU Swap

If Acorn had used a Z80, then I would have expected them to have designed the system to “boot” to BASIC in ROM. Just like the 6502 BBC Micro does. Interestingly, Research Machines, which had not bid for the BBC contract, once the BBC micro was taking part of their market in education, developed the...
by Coeus
Tue Feb 12, 2019 10:02 pm
Forum: other vintage computer hardware, software and games
Topic: Early Rare Digital Synth on CP/M Machine in Action...
Replies: 6
Views: 403

Re: Early Rare Digital Synth on CP/M Machine in Action...

I bet that's just crying out for a MIDI card, if there was enough processing capability to handle it. Not on the original machine, but if you read the full thread BrokenARM linked, a friend of his was able to implement one that sits between the keyboard/controller and the processor. The sound sampl...
by Coeus
Tue Feb 12, 2019 7:38 pm
Forum: off-topic
Topic: Sound Export
Replies: 35
Views: 1143

Re: Sound Export

I finally ended up using the debugger in B-Em to monitor writes to the sound IC, and sent a middle-C BELL, and it wrote &EE which gives 525Hz which is C above middle C (very approximately, middle C is 256Hz). C above C is SOUND 149 not SOUND 101, making middle C SOUND 53. Which. Makes. No. Sense. H...
by Coeus
Tue Feb 12, 2019 4:35 pm
Forum: off-topic
Topic: Retro upgrades, value for money, eBay & why bother?
Replies: 56
Views: 1938

Re: Retro upgrades, value for money, eBay & why bother?

At the other end you've got hipster-types who don't know much about the original kit and are used to paying Amazon prices for mass produced stuff from China. They have little to no idea what it costs or how long it takes to develop and assemble the products, they just think it seems expensive when ...
by Coeus
Tue Feb 05, 2019 11:45 pm
Forum: general
Topic: Why was Repton so loved by BBC users yet so disliked by the Commies?
Replies: 88
Views: 2883

Re: Why was Repton so loved by BBC users yet so disliked by the Commies?

...A quick example; the standard 6502 has no ability to disconnect the address and data buses from the rest of the system, something that's needed for DMA. In the VIC-20 Commodore had to put four bus buffer chips on the motherboard to do that job. For the C64 they designed a modified 6502, the 6510...
by Coeus
Tue Feb 05, 2019 11:27 pm
Forum: software: other
Topic: BBC *Status Command (and odd characters)
Replies: 24
Views: 627

Re: BBC *Status Command (and odd characters)

I guess the question therefore is whether there would be any merit in a Teletext printer convertor (which would be in addition to the ESC/P and PCL convertors). It would be based on the explanation at http://central.kaserver5.org/Kasoft/Typeset/BBC/Ch28.html If the Retro Printer is behaving like a ...
by Coeus
Tue Feb 05, 2019 10:09 pm
Forum: software: other
Topic: BBC *Status Command (and odd characters)
Replies: 24
Views: 627

Re: BBC *Status Command (and odd characters)

Or like this in Mode 7:
status.png
The other interesting thing I notice about that ROM is does the OSBYTE version of *TV in response to ROM service call 1 this shifting the display up. This does seem to be a ROM that suited the authors taste.
by Coeus
Tue Feb 05, 2019 6:58 pm
Forum: general
Topic: Why was Repton so loved by BBC users yet so disliked by the Commies?
Replies: 88
Views: 2883

Re: Why was Repton so loved by BBC users yet so disliked by the Commies?

A computer is a processor, memory, and input / output devices that can perform useful work. So a Wii is a computer, as it has all those elements. Games consoles are just specialist computers. In the same way that there are many other designs of specialist computers. True, program development is mor...
by Coeus
Tue Feb 05, 2019 6:48 pm
Forum: general
Topic: Why was Repton so loved by BBC users yet so disliked by the Commies?
Replies: 88
Views: 2883

Re: Why was Repton so loved by BBC users yet so disliked by the Commies?

Indeed. But there's also an elephant in the room. British computer manufacturers were almost uniform in being too blooming cheap to invest in the one thing they really needed; custom chip design. If Sinclair had been able to fund custom video and sound chip designs, rather than sticking with 8-bit ...
by Coeus
Tue Feb 05, 2019 3:38 pm
Forum: software: other
Topic: BBC *Status Command (and odd characters)
Replies: 24
Views: 627

Re: BBC *Status Command (and odd characters)

Can someone with a printer connected to the BBC please check how the *STATUS command appears when printed on a dot matrix printer? There is no *STATUS command on a standard BBC B with OS 1.20. There is a *STATUS command on a BBC Master but that gives different output from what you are trying to pri...
by Coeus
Tue Feb 05, 2019 2:04 pm
Forum: general
Topic: Bit of fun - One change only
Replies: 82
Views: 2504

Re: Bit of fun - One change only

So without the contraint about it being cheap, it would have to be shadow RAM. As 16K would not be enough, my plan would be to make the bottom 1K of RAM common to both banks and then switch the whole of the next 31K between the two banks. This would put OSHWM at &0400 on both I/O processor and tube ...
by Coeus
Mon Feb 04, 2019 8:01 pm
Forum: software: other
Topic: Extended vectors - huh?
Replies: 17
Views: 1288

Re: Extended vectors - huh?

One example where it would obviously go seriously wrong is if you trapped BRKV that way. Surely not. The OS selects the current language before dispatching via BRKV. See this code from the OS: DC27 TXA ;save X on stack DC28 PHA ; DC29 TSX ;get status pointer DC2A LDA &0103,X ;get Program Counter lo...
by Coeus
Mon Feb 04, 2019 1:54 pm
Forum: software: other
Topic: Extended vectors - huh?
Replies: 17
Views: 1288

Re: Extended vectors - huh?

I'm not clear: are you saying you believe that's not a problem, or were you ignoring that consideration? It is certainly possible to imagine a case where it could be a problem. For example, someone writes a piece of code that is assembled from BASIC, calls subroutines in the BASIC ROM and thus reli...
by Coeus
Sun Feb 03, 2019 10:31 pm
Forum: emulators
Topic: B-em on OSX with M5000 support
Replies: 14
Views: 517

Re: B-em on OSX with M5000 support

I can't offer to compile B-Em for OSX as I don't have a Mac and don't have any immediate plans to buy one. I do think someone did compile it on OSX recently, though. I believe Allegro 5 supports OSX, most of B-Em is ANSI C with a little bit of POSIX that Windows seems to implement so OSX should supp...