Search found 1848 matches

by RobC
Tue Jan 16, 2018 8:42 am
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3644

Re: VideoNuLA boards

Has anybody used the nULA board in a Master Compact? I have one in my Compact and it fits without any problems as long as you don't have an Econet module fitted. However, mine doesn't have a floppy inside the case so I don't know if it'll fit in yours. I keep meaning to try putting VideoNuLA at the...
by RobC
Sun Jan 14, 2018 9:57 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Batman the movie Beach buggy simulator More tea vicar (lots of particles) Repton 1 and 2 ported by Gil who wrote Jeltron with me in the 80s. No scrolling, but what does bomb Jack look like ;) Thanks tricky. Haven't tried Bomb Jack yet but I played the Spectrum version on an emulator when I was look...
by RobC
Sun Jan 14, 2018 7:18 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

A good *test* would be running z80 BBC basic for the spectrum on it. Great idea - I'll try it as soon as I can. The emulator can only load snapshots at the moment but I can add ROM loading. This looks really cool! Waiting patiently for the release. Can we update VideoNula ourselves, or do we have t...
by RobC
Sun Jan 14, 2018 4:32 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

mlouka wrote:When trying out your ZX81 emulator, I ended up using a real ZX81 as a "keystrip"!

Good idea :D I've now setup my Spectrum next to the Beeb!
by RobC
Sun Jan 14, 2018 10:25 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Wow, wow and wow! From pun to reality in a very short period of time. Amazing! Thanks - the idea was all yours though :) . Progressing from the ZX81->Jupiter Ace->Spectrum helped. When will I be able to play Bards Tale? I'm going to try to get something usable out in the next week or so. I'm also h...
by RobC
Sat Jan 13, 2018 10:16 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

This looks really cool. Thanks Dave - it wouldn't be possible without the Pi co-pro :D It's a lot of fun running a Spectrum on my Beeb but I'd forgotten just how many keywords were crammed onto the keys and it's really hard when the keys only have the letters on them. However, my six-year-old daugh...
by RobC
Sat Jan 13, 2018 6:11 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

crj wrote:If you're writing to the tube from emulated hardware, i.e. directly within the PiTubeDirect code, maybe you can be certain of keeping the FIFO from becoming empty? If so, you could go a little faster by not polling the status register.

Good point - I'll give it a go...
by RobC
Sat Jan 13, 2018 5:54 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

If you are going to hack around in OSWRCH, isn't it more efficient to keep a copy of screen memory on the Parasite and send actual values rather than values to EOR, by the way? This is how I do it with my emulators (ZX81, Ace and Spectrum). I've now implemented the equivalent of hoglet's OSWRCH mec...
by RobC
Sat Jan 13, 2018 4:34 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Isn't the defined - and quickest - way to do this stuff for the Parasite to provoke the Host into initiating a memory transfer? 256-byte blocks can be transmitted at the rate of 100Kbytes per second, because of the reduced handshaking overheads. And the Beeb end can do what it wants with each byte ...
by RobC
Sat Jan 13, 2018 3:35 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Whereas the full VDU handler presumably has overhead, once the new handler sees an FF it starts to pull data directly from the Tube chip - and as it's host side, that's a fairly justifiable thing to do. Overall, the full VDU stack penalty is paid once per screen. Many thanks for that - I understand...
by RobC
Sat Jan 13, 2018 2:28 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

As the copro runs ridiculously fast, overhead on that side of the Tube mightn't amount to much - I'd guess overhead on the host side is the case to worry about. But it might well be better to experiment than to theorise... Yes - I wanted to avoid handling lots of calls on the host. I think there pr...
by RobC
Sat Jan 13, 2018 12:56 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Interesting... I just checked to see how Dave managed to extend the Tube protocol for the second processor Life. It turns out - and now I do remember this - he extends the VDU protocol. Thanks for that Ed - I hadn't seen it so it was interesting to look through the code. I chose to extend OSWORD so...
by RobC
Sat Jan 13, 2018 8:50 am
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Is the Pi fast enough to look for small areas of shifted/scrolled graphics and send a scroll command for an area? I would think so. My current screen refresh routine is very simple as it just sends the address and value for every byte of pixel data that needs to change as a set of triplets. Attribu...
by RobC
Fri Jan 12, 2018 10:30 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

Re: SpectROM - Speccy emulator for the Pi co-pro

Thanks for the encouragement. Will this require the VideoNuLA or will it run without with “interesting” colours? It needs VideoNuLA, as apart from the colours, it uses a new attribute mode that's able to mimic the Spectrum's display. I had to modify the VideoNuLA VHDL to implement this so there's cu...
by RobC
Fri Jan 12, 2018 4:52 pm
Forum: hardware
Topic: SpectROM - Speccy emulator for the Pi co-pro
Replies: 35
Views: 888

SpectROM - Speccy emulator for the Pi co-pro

Following Lardo's suggestion in the ZX81 emulator thread, I decided to have a go at a ZX Spectrum emulator. After a lot of squeezing of code, I managed to fit an extra attribute mode into VideoNuLA that can mimic the Spectrum's display. Over Christmas I started to write an emulator for the Pi co-pro...
by RobC
Sun Jan 07, 2018 3:16 pm
Forum: hardware
Topic: A3020 Restoration
Replies: 14
Views: 301

Re: A3020 Restoration

IIRC, from the A3020 i repaired a few years ago, the RTC/CMOS chip is further away from the battery in the A3020 so this might not be such a problem. However, it's the HDD/floppy interface 82C711 and multiple associated tracks which are first in line for damage on this one :( Ah, true Steve - I'd f...
by RobC
Sat Jan 06, 2018 5:01 pm
Forum: hardware
Topic: A3020 Restoration
Replies: 14
Views: 301

Re: A3020 Restoration

What is the recommended mod to add a battery again? And will they boot without a battery? A working machine should boot without a battery but will probably need its CMOS RAM settings to be reset. See here for how to reset them (you hold down the required key on power-up): http://www.riscos.com/supp...
by RobC
Fri Jan 05, 2018 10:33 pm
Forum: hardware
Topic: A3020 Restoration
Replies: 14
Views: 301

Re: A3020 Restoration

JannievanZyl wrote:Or don't they need drives to boot?

They boot from ROM so don't need a hard drive (but a hard drive is a very useful addition).

The corrosion can damage PCB tracks and my experience is that the connections to the floppy, hard drive and parallel port can be badly affected on the A3020.
by RobC
Fri Dec 29, 2017 3:16 pm
Forum: hardware
Topic: Acorn Ethernet 3 podule EPROM and RISCiX
Replies: 8
Views: 321

Re: Acorn Ethernet 3 podule EPROM and RISCiX

Here's the ROM image from my Ethernet III podule. The EPROM was an ST M27C1001.

It's dated from 1992 so I guess there's a good chance it'll work with RO2 as I'm pretty sure I got hold of my first RO3 ROMs in late 92...
by RobC
Thu Dec 28, 2017 5:23 pm
Forum: hardware
Topic: Acorn Ethernet 3 podule EPROM and RISCiX
Replies: 8
Views: 321

Re: Acorn Ethernet 3 podule EPROM and RISCiX

I don't believe RISCiX worked (at least, not without some tweaks by Brian Brunswick that I'm not sure ever saw the light of day) with any Ethernet podules other than EtherH and EtherB. And those didn't need a ROM in for RISCiX to recognise them and work with them. I have one of these in my R260 and...
by RobC
Wed Dec 27, 2017 3:42 pm
Forum: hardware
Topic: Additional RAM board
Replies: 14
Views: 395

Re: Additional RAM board

I did try programming but RAM rapidly disappears when higher resolution screens are used so the RAM expansion board could be useful here. That's pretty much what the board is designed to combat so it sounds like it would be useful for you. If you're into programming, the Pi co-pro is a great and in...
by RobC
Wed Dec 27, 2017 2:14 pm
Forum: hardware
Topic: Additional RAM board
Replies: 14
Views: 395

Re: Additional RAM board

I have a couple of these boards but have never really used them. One is fitted to one of my Beebs but the other is still in its box. The manual can be found here: http://chrisacorns.computinghistory.org.uk/docs/Watford/WE_32KRAMcard.pdf You'll need to install the supporting ROM if it's not already f...
by RobC
Thu Dec 21, 2017 8:12 pm
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3644

Re: VideoNuLA boards

Thanks. A suggestion: put a "parameter" column in the auxilary register summary table on on page 28 as an aide memoir, something like: code | function | parameter 1 | set palette mode | physical/logical mapping 2 | set horizontal | offset offset 3 | set left blanking size | size 4 | reset...
by RobC
Thu Dec 21, 2017 11:18 am
Forum: for sale / freebies
Topic: VideoNuLA boards
Replies: 43
Views: 3644

Re: VideoNuLA boards

Edit: the manual says writing &4x to the control register reset nULA to its default state, then lists these default states, but the &FE23 toggle is not listed in that list. The reset command (?&FE22=&4x or *VNRESET) also resets the toggle state so that the next poke to &FE23 set...
by RobC
Wed Dec 20, 2017 10:13 pm
Forum: hardware
Topic: Acornsoft GXR and Datacentre
Replies: 4
Views: 308

Re: Acornsoft GXR and Datacentre

Just had a quick play with this on B-Em (I can't access most of my Beebs as my man cave is full of Christmas presents!) and get the same issue with ADFS 1.33 and GXR 1.2 when the GXR ROM is in a higher slot that ADFS. With GXR in a lower slot, it seemed to work okay but I didn't do an exhaustive tes...
by RobC
Sat Dec 16, 2017 6:06 pm
Forum: hardware
Topic: BeebSCSImini
Replies: 34
Views: 1321

Re: BeebSCSImini

For the matchbox copros, I just took a 40-way female-female cable, cut off one end and added one of these instead: https://www.ebay.co.uk/itm/252083808451 They sell the 34-way version with and without mounting lugs. I think the price was pretty competitive when I bought them but haven't checked in t...
by RobC
Sat Dec 16, 2017 11:56 am
Forum: emulators
Topic: Emulator support for VideoNuLA
Replies: 60
Views: 3743

Re: Emulator support for VideoNuLA

I don't have the real hardware so don't know what should actually happen... Redefining black in mode 7 causes the display's reference voltage to change. This effectively causes whatever colour you've set black as to be "subtracted" from all the other colours. (This only applies to mode 7,...
by RobC
Thu Dec 14, 2017 11:34 pm
Forum: hardware
Topic: BBC Master screen interference PiTube direct
Replies: 55
Views: 1191

Re: BBC Master screen interference PiTube direct

There is evidence of it in the 'new zx81' emulator by ROBC using the the native ARM proc, with the issue being inverted. i.e. the artifacts are white on black. That'll be because the ZX81 emulator uses a mode 4 screen with an inverted palette (so that '0' is white and '1' is black in the main displ...
by RobC
Tue Dec 12, 2017 7:13 pm
Forum: for sale / freebies
Topic: BeebSCSI mini
Replies: 108
Views: 6700

Re: BeebSCSI mini

Mine arrived too - many thanks Jason!
by RobC
Tue Dec 12, 2017 5:57 pm
Forum: other vintage computer hardware, software and games
Topic: Looking for a Tatung Einstein book
Replies: 2
Views: 127

Re: Looking for a Tatung Einstein book

I don't have a copy but it's listed as "Coming soon" on here: http://www.tatungeinstein.co.uk/front/mans.htm

Mario (who owns the site), was on here as Mazza352 a while back. Maybe worth contacting him?

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