Search found 2061 matches

by BigEd
Fri Sep 21, 2018 12:18 pm
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

(Just to say, Richard, while it's always pity to hear about deteriorating health, it's excellent that you are opening the software and handing over the reins to posterity, even if not to a specific person or team.)
by BigEd
Fri Sep 21, 2018 11:16 am
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

I think having an assembler embedded in a high level language should still be a big win - not for very many people, perhaps, but for those who find it useful, or want to dabble in assembly, the practice of first writing a program and then porting critical sections to assembly should still be compell...
by BigEd
Thu Sep 20, 2018 8:35 am
Forum: general
Topic: Best Basic Games
Replies: 9
Views: 243

Re: Best Basic Games

was fun - and even more so, as I recall, with a small tweak to the input routine so you could pre-select a turn.
by BigEd
Thu Sep 20, 2018 7:12 am
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

Richard Russell wrote:
Wed Sep 19, 2018 10:37 pm
... you may still need to run the 32-bit version using:

Code: Select all

IBUS_ADDRESS=0 ./bbcsdl
BTW, a portability tip, as people may run different shells. This syntax is acceptable to all shells, AFAIK:

Code: Select all

env IBUS_ADDRESS=0 ./bbcsdl
by BigEd
Mon Sep 17, 2018 7:53 pm
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

Having a project out in the open is a step towards getting contributors. It might not happen very soon, but it has every chance of happening. Seeing the code and wanting to work on it is a stimulus. The zlib license would also be a reasonable choice. But choosing anything that's more permissive woul...
by BigEd
Mon Sep 17, 2018 7:06 pm
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

... you could always withhold (reserve) the right to create derived works ... Might be worth noting that this is the default: things can't be copied unless the creator says they can be copied. For this reason it's really helpful to add a suitable license to your project or your source files. My obj...
by BigEd
Thu Sep 13, 2018 5:10 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 18 to 20 January 2019 (Hampshire) DATE CONFIRMED
Replies: 15
Views: 388

Re: ABUG SOUTH 18 to 20 January 2019 (Hampshire) DISCUSSION THREAD

When it comes time to do a booking thread, can I suggest you do something to help people who are not on the forum 24/7? For example, pre-announce a booking window at least a day ahead; maybe open only half the places in the first booking window and then have another; maybe reserve some places for pe...
by BigEd
Wed Sep 12, 2018 10:08 pm
Forum: software & utilities for the pc, mac or unix
Topic: Request for help in organising/releasing source code
Replies: 79
Views: 1498

Re: Request for help in organising/releasing source code

I think what I'll do is try to create a zip file, then people can comment on that without worrying about the complication of Github. I should perhaps make clear, again, that I am not proposing to release the assembler code currently used to build BB4W and the 32-bit x86 builds of BBCSDL, but only t...
by BigEd
Mon Sep 10, 2018 11:08 am
Forum: hardware
Topic: I2C 4 U
Replies: 243
Views: 15026

Re: I2C 4 U

Is that the cooling curve of a hot can of fizzy orangeness?
by BigEd
Sun Sep 09, 2018 6:39 pm
Forum: upcoming and recent events & exhibitions
Topic: Anything coming up in SW UK?
Replies: 16
Views: 503

Re: Anything coming up in SW UK?

There's a possibility of an RC2014 event in Bristol, on a Tuesday evening. Spencer would need to see some interest though, so it would be worth pinging him if you're up for it: RC2014 Meetup - 18th September, Bristol UK (RC2014 started life as a Z80 mini-backplane design, but can take a 6502 or 6809...
by BigEd
Sun Sep 09, 2018 7:45 am
Forum: hardware
Topic: Pi based Prisma 3 emulation connected via 1Mhz bus
Replies: 7
Views: 324

Re: Pi based Prisma 3 emulation connected via 1Mhz bus

Looks like there's a BSD-licensed C model of the ACRTC in MAME: https://github.com/mamedev/mame/blob/master/src/devices/video/hd63484.cpp That should help. Aside from getting the performance lined up so the three overlays can be soft-blitted into the visible frame buffer in time for a 50Hz frame rat...
by BigEd
Sun Sep 09, 2018 7:39 am
Forum: other vintage computer hardware, software and games
Topic: A micro-controller for the retro enthusiast
Replies: 3
Views: 222

Re: A micro-controller for the retro enthusiast

It's an interesting experiment in small-scale custom IC production - despite using free tools and free engineering effort, it aims to raise $20k for a production run. It might be that the retro-computing fanbase is large enough to support custom ICs: time will tell. It's very encouraging that the RC...
by BigEd
Thu Sep 06, 2018 3:58 pm
Forum: hardware
Topic: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)
Replies: 1082
Views: 96867

Re: Pi-based Co-Pro on the cheap - 100MHz 6502 for £10? (now 274MHz)

Give it a go: tinycorelinux is a distribution which runs from RAM.
http://tinycorelinux.net/ports.html

Or, possibly, use a linux on USB instead of SDcard - I have an idea it will react much better to abrupt power-off.
by BigEd
Thu Sep 06, 2018 3:27 am
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 642

Re: BBC BASIC integer arithmetic

Richard Russell wrote:
Wed Sep 05, 2018 10:18 pm
So, probably through luck rather than design, it seems the 'multiplication' behaviour has the effect of masking the 'wrap' behaviour, and it's quite likely only for this reason that the latter wasn't identified as a serious weakness long ago.
An interesting thought!
by BigEd
Wed Sep 05, 2018 5:06 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 502

Re: NMI/IRQ timing to vector pull

Hmmmmmmm. I'm finding this very confusing! The branch takes three cycles, so it's a taken branch. I thought irq and nmi had different latencies but that seems not to be the case. With the nominal timing of irq falling in the cycle after sync, the next instruction is executed, as we'd expect for an N...
by BigEd
Wed Sep 05, 2018 4:24 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 502

Re: NMI/IRQ timing to vector pull

(Searching for d1x1 on 6502.org is the way to find some of the experiments done with visual6502. That's the internal signal which indicates a commitment to take an interrupt.)
by BigEd
Wed Sep 05, 2018 4:23 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 502

Re: NMI/IRQ timing to vector pull

I don't know the details of the 'c02 in this area... perhaps one of the test programs in the 2006 thread that Dave linked would help here? Nightshade protection [technical] I'd be a bit surprised if this branch behaviour were changed, as I think we did eventually figure out the sense of it, in this ...
by BigEd
Wed Sep 05, 2018 3:25 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 502

Re: NMI/IRQ timing to vector pull

You've just reminded me of something, which I think I got from Dr Jefyl on the 6502 forum: if A0 doesn't flip in the cycle after SYNC, then you're in the beginnings of an interrupt being taken. So, that's slightly earlier warning. (Again, in general RDY might affect this, but surely not on a SYNC cy...
by BigEd
Wed Sep 05, 2018 12:06 pm
Forum: hardware
Topic: NMI/IRQ timing to vector pull
Replies: 22
Views: 502

Re: NMI/IRQ timing to vector pull

I think it's enough to wait for three writes in a row - that can only be the dumping of state to the stack in the servicing of an interrupt. The very next two cycles are the vector fetches. If this is so, you don't need to worry about Sync or about the behaviour of different instructions (like taken...
by BigEd
Tue Sep 04, 2018 4:09 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 642

Re: BBC BASIC integer arithmetic

Isn't a shortcut for smaller arguments an independent choice from the integer wrapping question?
by BigEd
Tue Sep 04, 2018 3:39 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 642

Re: BBC BASIC integer arithmetic

Interesting - this certainly shows that they thought about what they were doing. It is a bit fast and loose though, especially against today's expectations. Perhaps at the time the expectation was that anyone writing a substantial or important Basic program would be pretty careful. It's still a bit ...
by BigEd
Tue Sep 04, 2018 1:12 pm
Forum: off-topic
Topic: Circuit Simulators
Replies: 37
Views: 411

Re: Circuit Simulators

And you really do want circuit simulation, not logic simulation? That is, you want Rs and Cs and waveforms, not just highs and lows?
by BigEd
Tue Sep 04, 2018 1:07 pm
Forum: off-topic
Topic: Circuit Simulators
Replies: 37
Views: 411

Re: Circuit Simulators

When you mentioned 3d, what did you mean? Simulation of airflow, heat dissipation??
by BigEd
Tue Sep 04, 2018 1:05 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 642

Re: BBC BASIC integer arithmetic

Integers do seem to wrap with addition, but for multiplication I'm getting 'too big'. This seems good to me.
by BigEd
Mon Sep 03, 2018 7:03 pm
Forum: off-topic
Topic: Circuit Simulators
Replies: 37
Views: 411

Re: Circuit Simulators

Oops - thanks for the correction!
by BigEd
Mon Sep 03, 2018 6:52 pm
Forum: off-topic
Topic: Circuit Simulators
Replies: 37
Views: 411

Re: Circuit Simulators

You can readily perform a logic-level simulation of an HDL model such as hoglet's
https://github.com/hoglet67/BeebFpga
by BigEd
Mon Sep 03, 2018 6:50 pm
Forum: software: other
Topic: Acornsoft P-System
Replies: 45
Views: 1515

Re: Acornsoft P-System

If the disks are not copy protected (and there are not too many files) you could *dump each file, and capture it over serial. But UPURS is good, if you can get the cable and ROM sorted.
by BigEd
Mon Sep 03, 2018 5:39 pm
Forum: off-topic
Topic: Circuit Simulators
Replies: 37
Views: 411

Re: Circuit Simulators

I did once simulate a 6502 at the transistor level - it ran about half a billion times slower than a Beeb. Of course you might have a faster computer than I did.
See this 2011 thread on 6502.org:
by BigEd
Mon Sep 03, 2018 2:46 pm
Forum: programming
Topic: BBC BASIC integer arithmetic
Replies: 52
Views: 642

Re: BBC BASIC integer arithmetic

Drat. I might well not have tried or seen what I'd thought. Sorry about that.