Search found 174 matches

by IanB
Sun Jan 28, 2018 7:02 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 40
Views: 1285

Re: RGB to HDMI using a Pi Zero and a small CPLD

I've just tried a quick test and enabled the line doubling (and double buffering) for Mode 7. As you say, it does introduce the twitter that you get on a real CRT (which I find quite distracting), but the combing and tearing are now gone. I doubt there is the memory bandwidth to do anything more co...
by IanB
Sat Jan 27, 2018 3:57 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 40
Views: 1285

Re: RGB to HDMI using a Pi Zero and a small CPLD

Yes, it likely does mean edge combing will be present. Doesn't bob effectively half the vertical resolution (i.e. each field is line doubled and written to two lines) I'm definitely open to ideas for how to improve this. Bob does reduce the effective vertical resolution a bit but not by half and it...
by IanB
Sat Jan 27, 2018 1:20 pm
Forum: hardware
Topic: RGB to HDMI using a Pi Zero and a small CPLD
Replies: 40
Views: 1285

Re: RGB to HDMI using a Pi Zero and a small CPLD

That's really neat =D> On startup the Pi runs an initial calibration phase that accurately measures the duration of two video fields (i.e. one frame). If the Beeb's clock is exactly 16MHz then the frame time should be exactly 40mS. Any error from this allows us to estimate the actual 16MHz clock fre...
by IanB
Tue Jan 09, 2018 1:10 am
Forum: hardware
Topic: Econet podule for RISCPC & A7000
Replies: 71
Views: 9770

Re: Econet podule for RISCPC & A7000

So I've been trying to make a full Econet podule - http://stardot.org.uk/forums/viewtopic.php?f=41&t=5594&start=4320#p189894 Very interesting! Looks like it can take a standard Econet module as well as discrete components. If I run "Podule_ReadInfo" (as the module does), with the ...
by IanB
Tue Jan 02, 2018 6:19 pm
Forum: emulators
Topic: Model A, OS 0.1 and disc interfaces
Replies: 10
Views: 620

Re: Model A, OS 0.1 and disc interfaces

The very first disc interface upgrades came with a free copy of OS 1.00 (not OS 1.20) in two 8K EPROMs on a small board, sometimes referred to as a "butterfly" board as the layout of the EPROMs vaguely resembled wings. That could be upgraded for free to OS 1.20 in ROM when it was released....
by IanB
Sat Dec 30, 2017 6:33 pm
Forum: acorn atom
Topic: Acorn Atom Econet
Replies: 15
Views: 868

Re: Acorn Atom Econet

I've tidied it into it's own place in http://mdfs.net/Apps/Networking/FServers/ That's a very interesting disc, it seems to contain a complete set of version 2 protocol Econet software for Atoms and Systems. This all predates BBC micro Econet as the ROMs for that started with version 3.xx and so th...
by IanB
Thu Dec 21, 2017 4:38 pm
Forum: hardware
Topic: BeebSCSImini
Replies: 38
Views: 1647

Re: BeebSCSImini

If the version number of ADFS is 1.50, 1.30 or 2.03 then it's likely the standard SCSI version.
by IanB
Wed Dec 20, 2017 5:47 pm
Forum: hardware
Topic: RIFA'd again
Replies: 6
Views: 483

RIFA'd again

In case anyone else here has one, the ARM1 evaluation system second processor power supply has RIFA capacitors.
I just found out the hard way...
by IanB
Wed Dec 20, 2017 12:31 pm
Forum: general
Topic: Acorn Internal Development Doc (early 80s)
Replies: 4
Views: 486

Re: Acorn Internal Development Doc (early 80s)

BigEd wrote:I'm aware of 'events' but not 'faults' - although we do have 'errors.'

That section just describes the use of BRK to generate error messages.
by IanB
Wed Dec 20, 2017 11:41 am
Forum: general
Topic: Acorn Internal Development Doc (early 80s)
Replies: 4
Views: 486

Re: Acorn Internal Development Doc (early 80s)

stmuk wrote:Does anyone recall this document or even still own a copy (even as PDF)?


Yes, I still have my copy:

OSp1.jpg

OSp2.jpg
by IanB
Sun Dec 17, 2017 10:21 pm
Forum: hardware
Topic: Disc Error 20/21/23 and SATA->IDE support
Replies: 40
Views: 1628

Re: Disc Error 20/21/23 and SATA->IDE support

SATA->IDE is a different issue. ... This can only be resolved with a hardware solution, one option is to use an adapter that does control -IOCS16. I've looked at dozens on eBay today and even though they say they support PIO, none of them visually appear to control -IOCS16, the pin appears to have ...
by IanB
Sun Dec 17, 2017 4:13 pm
Forum: hardware
Topic: BeebSCSImini
Replies: 38
Views: 1647

Re: BeebSCSImini

I was just curious as to the response from the master if you have two LUNs (0 and 1) and you issue *MOUNT 2. What does the Master respond with? *MOUNT 0 mounts OK *MOUNT 1 mounts OK *MOUNT 2 "Not Found" *MOUNT 3 "Not Found" The Adaptec hardware only supports 2 LUNs so I'm not su...
by IanB
Sun Dec 17, 2017 12:55 am
Forum: hardware
Topic: BeebSCSImini
Replies: 38
Views: 1647

Re: BeebSCSImini

Edit2: Can you verify what error you get if you issue a command to a non-existent LUN on the real hardware? The error number should give me a clue as to which SCSI command (the START or READ) returns error in this case. Not sure how you want me to test that. If you try to access a non existant driv...
by IanB
Fri Dec 15, 2017 11:46 pm
Forum: hardware
Topic: BeebSCSImini
Replies: 38
Views: 1647

Re: BeebSCSImini

The bug is that you get a disc error when trying to access HD1 after a power up (or *bye) unless you *mount it first This doesn't happen with a pair of ST506 HDs connected to an Adaptec SCSI controller / host interface and I assumed you were aiming to emulate the behaviour of that standard hardware ...
by IanB
Fri Dec 15, 2017 6:22 pm
Forum: hardware
Topic: BeebSCSImini
Replies: 38
Views: 1647

Re: BeebSCSImini

Found a bug with more than one HD: (Tested on a Master 128) After powering on the Master and beebSCSImini, if you type LOAD":0.XYZ" you get "not found" (assuming the file doesnt exist) but if you type LOAD":1.XYZ" you get a disc error at sector 000000 If you then type *...
by IanB
Thu Dec 14, 2017 11:44 pm
Forum: hardware
Topic: Open source firmware for Gotek floppy emulator released
Replies: 78
Views: 4792

Re: Open source firmware for Gotek floppy emulator released

Looks interesting. I wonder if it would be possible to add a feature to pass info back to the Gotek from the host computer to select disk images so you could then have large games menus like the MMC type systems which auto select the appropriate disc. e.g. something like seeking to tracks 100-109 to...
by IanB
Tue Dec 05, 2017 8:59 pm
Forum: hardware
Topic: Clwyd Technics Colour Palette enhancer
Replies: 7
Views: 430

Re: Clwyd Technics Colour Palette enhancer

There were several products like that back in the 80s and I designed one of them although I can't remember the company I did it for. My one hooked up to the 1Mhz bus and gave you an additional user port as well. I think it was done like that so it could be used with a mouse on the standard user port...
by IanB
Fri Aug 11, 2017 7:13 pm
Forum: other vintage computer hardware, software and games
Topic: UK101 Hardware Modifications Archive
Replies: 21
Views: 1347

Re: UK101 Hardware Modifications Archive

I did try this 'no snow' mod a while ago and it did not work at 2 MHz on my UK101 so abandoned it. I couldn't get my UK101 to run at 2Mhz so never tried it but I'm not surprised it doesn't work as it relies on both the character clock of the video system and the CPU running at 1Mhz so they can both...
by IanB
Fri Aug 11, 2017 4:58 pm
Forum: other vintage computer hardware, software and games
Topic: UK101 Hardware Modifications Archive
Replies: 21
Views: 1347

Re: UK101 Hardware Modifications Archive

I previously posted this in another thread but as you are collecting mods in one place, here's my "no snow" modification which was published in the December 1981 issue of PC World:

PCWpage147.jpg

This mod might not work when running the CPU at 2Mhz
by IanB
Thu Sep 29, 2016 6:45 pm
Forum: software: other
Topic: The Artist by Wigmore House
Replies: 27
Views: 1740

Re: The Artist by Wigmore House

Has anyone got a manual for 'The Artist' by Wigmore House please. It's not online anywhere....only the rom. I didn't write 'The Artist' but I converted it for the Commodore 64. As a result I still have all the original source files for the BBC version including the draft manual in Wordwise format. ...
by IanB
Wed Sep 21, 2016 4:41 pm
Forum: hardware
Topic: Utterly weird Model B vs Master 128 timing issue
Replies: 23
Views: 1260

Re: Utterly weird Model B vs Master 128 timing issue

On my Master 128, the timing is almost (but not entirely OK). However, on my Model B, I noticed that it was running rather slow. At first, I wondered whether it was something to do with the hardware in my Model B (which has been having a variety of issues). However, my Master 128 has a multi OS ROM...
by IanB
Tue Sep 20, 2016 6:28 pm
Forum: hardware
Topic: Finding a genuine Sandisk 512MB card
Replies: 21
Views: 1891

Re: Finding a genuine Sandisk 512MB card

steve3000 wrote:Ian, did you get those converters working using the Wizzo ROM?


Yes that type of converter does work in an A5000 with the Wizzo ROM but not using the native RISCOS drivers (I got broken directory all the time)
However I stopped using the Wizzo ROM because of the command line path bug.
by IanB
Tue Sep 20, 2016 9:59 am
Forum: hardware
Topic: Finding a genuine Sandisk 512MB card
Replies: 21
Views: 1891

Re: Finding a genuine Sandisk 512MB card

DutchAcorn wrote:
topcat96 wrote:@DutchAcorn
Ever considered using an adaptor?

Thanks Topcat, I'll try that.


I've tried those adapters but they don't work on my A5000. They do work well on my two RISC PCs.
by IanB
Tue Aug 09, 2016 5:20 pm
Forum: hardware
Topic: Acorn System FPGA
Replies: 6
Views: 913

Re: Acorn System FPGA

I'm wonder what, if any, other software exists that might run on this? The only System software I have is the level 2 econet file server: system5.jpg Here's the ROM image and file server software. Sys5RomFS.zip Edit: Forgot to mention the ROM image is 8K and the first 4K is the Econet driver (E000-...
by IanB
Sat Jul 30, 2016 10:13 pm
Forum: general
Topic: [VIDEO] What were your worst tape loading issues?
Replies: 9
Views: 720

Re: [VIDEO] What were your worst tape loading issues?

About 10 years ago I bought a couple of old untested ZX80 game tapes off ebay which were for flicker free games. These weren't available online anywhere and quite rare at the time. Unfortunately although they sounded OK they were completely unreadable by the ZX80 and adjusting the azimuth didn't hel...
by IanB
Sat Jul 23, 2016 10:03 pm
Forum: hardware
Topic: 1024x768 and 15KHz TV modes on an A5000 with BenQ BL912 monitor
Replies: 29
Views: 2811

Re: 1024x768 and 15KHz TV modes on an A5000 with BenQ BL912 monitor

Wonder if it works with an amstrad CPC. It would need some interface circuitry which I am working on at the moment. As mentioned above, the RGB signals on the VGA input require some filtering to get rid of aliasing effects and I'm experimenting with that. Also the VGA input needs TTL level sync sig...
by IanB
Sat Jul 23, 2016 9:26 pm
Forum: hardware
Topic: 1024x768 and 15KHz TV modes on an A5000 with BenQ BL912 monitor
Replies: 29
Views: 2811

Re: 1024x768 and 15KHz TV modes on an A5000 with BenQ BL912 monitor

Any chance these can be made to work on an ARM250 machine? I've always wanted to overclock the VIDC core :D I've already used paulv's boad with the adafruit module on my A4000 which is ARM250 based so that should work on other ARM250 machines. see these posts above: http://stardot.org.uk/forums/vie...
by IanB
Thu Jul 07, 2016 6:38 pm
Forum: hardware
Topic: Fettling an A3000 and now it's overly fast...
Replies: 15
Views: 1056

Re: Fettling an A3000 and now it's overly fast...

I'm actually coming to the conclusion that the 24MHz oscillator is running a little bit fast That shouldn't make much difference as the memory/cpu cycles and the timer used to measure that are all derived from the same 24 Mhz crystal so if it's running 10% fast, the cpu will be 10% faster but the t...
by IanB
Wed Jul 06, 2016 5:16 pm
Forum: hardware
Topic: Fettling an A3000 and now it's overly fast...
Replies: 15
Views: 1056

Re: Fettling an A3000 and now it's overly fast...

I notice that DRAM refresh is set to "None". The MEMC datasheet indicates it can be set to none for high resolution modes but on my machines it shows as "During Video Flyback only (4uS)" in all modes unless I use the option to disable the video during the test in which case it sh...
by IanB
Mon Jul 04, 2016 7:11 pm
Forum: hardware
Topic: ICS Wizzo IDEFS for A5000/A4 (+A3020/A4000...) improves CF card support!
Replies: 61
Views: 4436

Re: ICS Wizzo IDEFS for A5000/A4 (+A3020/A4000...!) and CF/SD adaptors

someone posted on here a while back about a similar issue with the ICS podule. I found that thread: http://www.stardot.org.uk/forums/viewtopic.php?f=16&t=8007 which leads here: https://groups.google.com/forum/#!topic/comp.sys.acorn.hardware/lumceUFWkXY And that indicates it can be caused by mis...