Search found 472 matches

by simoni
Sun Jun 23, 2019 8:29 pm
Forum: software: other
Topic: The Stappenmaster Domesday Disc...
Replies: 5
Views: 211

Re: The Stappenmaster Domesday Disc...

The patterning on the surface of the disc and the CLV format are the tells that it's for calibration; there are a number of similar examples of such laserdiscs produced for internal R&D and manufacturing purposes. The VP415 was developed specifically for Domesday, so the label isn't surprising (see ...
by simoni
Sun Jun 23, 2019 4:04 pm
Forum: software: other
Topic: The Stappenmaster Domesday Disc...
Replies: 5
Views: 211

Re: The Stappenmaster Domesday Disc...

There were no Domesday prototypes that used Teletext as far as all first-person and documented accounts show. The BBC produced the commercial Garden Birds disc which contained teletext as an experiment in interactive video (which was successful) - the success of that was used to prove the early viab...
by simoni
Tue Jun 11, 2019 8:21 pm
Forum: hardware
Topic: Data Center Discontinued?!
Replies: 13
Views: 420

Re: Data Center Discontinued?!

It's also worth mentioning that BeebSCSI was designed from scratch to be an open-design; both the hardware and the firmware in the solution are fully documented, not just from the user's perspective, but also from a technical implementation too. Plus BeebSCSI isn't a patched IDE implementation with ...
by simoni
Thu Jun 06, 2019 4:56 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

Good point, I'll fix it next time I'm working on the schematic (as it's pretty minor)
by simoni
Thu Jun 06, 2019 4:44 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

The RTC part number has been updated and the revised version is now on github.
by simoni
Thu Jun 06, 2019 11:47 am
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

I just checked an issue 1 Master PCB and pins 1 and 16 are not connected. The chip markings (removed from the same issue 1 board) state "MC146818P". The original schematic only says 146818 and the chip datasheet for the MC146818P states that 1 and 16 are NC. So I'd conclude that both the new schemat...
by simoni
Wed May 01, 2019 5:06 pm
Forum: hardware
Topic: Issue 4 Beeb - Modification
Replies: 2
Views: 149

Re: Issue 4 Beeb - Modification

At a glance I'd say it was to modify the VREF voltage to the ADC IC (the diodes are used to drop the voltage from the 5V supply). Since D6,7 and 8 are most likely still in place, you can safely remove it (leaving it in place will probably cause analogue joysticks to have a modified swing).
by simoni
Sun Apr 28, 2019 8:20 pm
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

I have seen issues where it causes a crash after about 3minutes.
Can you let me know the BeebSCSI board revision and firmware version you were running when you observed the crash?
by simoni
Fri Apr 26, 2019 11:33 am
Forum: hardware
Topic: Music 5000 clone in Kicad - Work in progress
Replies: 28
Views: 1162

Re: Music 5000 clone in Kicad - Work in progress

With the original spec 74LS ICs it's drawing about 400mA off the wall-wart, and the chips get quite warm. As an experiment I replaced about a dozen of the 74LS chips with 74HC equivalents I had in my parts store - and it appears to still function OK, but now draws about 300mA, and they don't get so...
by simoni
Wed Apr 17, 2019 7:46 pm
Forum: hardware
Topic: Raspberry Pi to 1MHz bus interface
Replies: 80
Views: 3834

Re: Raspberry Pi to 1MHz bus interface

Perfect, thanks! The BBC Master is my usual go-to machine, and these boards don't usually fit underneath. Whilst the converter is fine for the Model B, mounting on a Master might be a little more tricky from a signal quality perspective which is why I wanted to take a look at it. I'll put the design...
by simoni
Wed Apr 17, 2019 5:33 pm
Forum: hardware
Topic: Raspberry Pi to 1MHz bus interface
Replies: 80
Views: 3834

Re: Raspberry Pi to 1MHz bus interface

Using diodes and resistors as a bidirectional level converter is a fairly standard trick (with caveats around pull-down): http://www.hobbytronics.co.uk/schottky-logic-level-conversion The advantage of the approach is that it's cheap; the disadvantage is that it skews the signal edges and doesn't wor...
by simoni
Tue Apr 16, 2019 7:13 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

Doesn't surprise me that TIME is inaccurate over long measurements (although, in this case, it's a very short measurement, so the inaccuracy should be less on average). My point was really that there is a difference between the overall operation speed and the actual data transfer speed (the 'speed t...
by simoni
Tue Apr 16, 2019 3:53 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

The speed test code on domesday86.com is very simple, it also measures the total operation time (as opposed to just the data transfer speed). The data transfer speed is much higher than quoted, but it's not really a practical measurement. Since BeebSCSI is open-source, I didn't feel the need to 'bum...
by simoni
Mon Apr 15, 2019 3:35 pm
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

If your code is repeatedly requesting a single 256 byte sector, it's going to be slow. It's also quite an unrealistic scenario since each read can pull back a couple of hundred sectors in a single call. You are basically driving the FAT stack in a manner which it isn't designed to be driven. It coul...
by simoni
Mon Apr 15, 2019 11:52 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

The first issue is probably due to the file server making multiple requests or sub-dividing the SCSI requests in some way. The second could be anything, from a BeebSCSI issue to a bug in the file server (I would guess that the file server is sending a STOP command to the LUN - which would cause Beeb...
by simoni
Mon Apr 15, 2019 5:15 am
Forum: hardware
Topic: Raspberry Pi to 1MHz bus interface
Replies: 80
Views: 3834

Re: Raspberry Pi to 1MHz bus interface

Is there a link to the PCB schematic and the source code? I don't like to plug anything new into my Acorn's unless I can see some schematics first :) Nice to see you've built upon my BeebSCSI code; I'm quite interested in how you did the CPLD part on the Pi; I'd been thinking about doing some Pi bar...
by simoni
Sun Apr 14, 2019 6:02 pm
Forum: hardware
Topic: The sound of BBC graphics!
Replies: 12
Views: 496

Re: The sound of BBC graphics!

The BBC's sound circuitry consists of a SN76489AN (which generates the sound), an LM324 quad op-amp which filters and pre-amps and a LM386 which acts as a power amp and drives the speaker. There are basically three sources of noise and distortion: 1) the chips themselves - they are not 'pro-audio' a...
by simoni
Sat Apr 13, 2019 11:46 am
Forum: hardware
Topic: Master IO Controller IC15 - Databus pins?
Replies: 4
Views: 150

Re: Master IO Controller IC15 - Databus pins?

There are used to select between internal and external tube and 1MHz bus. ( fe34) Thanks! Makes a lot of sense :) &FE34 is the ACCCON register though... the documentation (Acorn engineering news 1) says that ACCCON is contained in the Memory Controller though (IC20): https://github.com/simoninns/Ac...
by simoni
Sat Apr 13, 2019 10:41 am
Forum: hardware
Topic: Master IO Controller IC15 - Databus pins?
Replies: 4
Views: 150

Master IO Controller IC15 - Databus pins?

The IO Controller IC15 in the Master (CF30050) has two data pins D4 and D5 connected to the CPU databus CD4 and CD5.

Does anyone know why? :)

(Even better if someone can point me in the direction of some reverse engineering for this chip)
by simoni
Tue Apr 02, 2019 9:07 am
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

I've just added the schematic for the 65C102 Master CoPro to the GitHub too. This one was reverse engineered from the original PCB as no Acorn schematic has ever been found for this add-on (as far as I know!). Along with the AIV SCSI board (already published by me a while ago) - this means all the A...
by simoni
Mon Apr 01, 2019 3:50 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

Anyone verified that the filestore problem is solved with the new build? It would be good to get a little feedback beyond my own testing :)
by simoni
Sun Mar 31, 2019 3:27 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

Thank you
You are very welcome :)
by simoni
Sun Mar 31, 2019 1:51 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

Re: BBC Master 128 schematic in KiCAD

There's a lot more information in a modern KiCAD schematic than there is available in a paper version; so it includes all the pin directions and types to allow the ERC to work - as well as the pins missing from the original schematic (and those marked as NC which should have had a signal). I also in...
by simoni
Sun Mar 31, 2019 10:27 am
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 596

BBC Master 128 schematic in KiCAD

As part of some other work I'm doing I've produced a complete Master 128 schematic in KiCAD - complete with all custom IC definitions, power distribution, decoupling, etc. The design also passes ERC. The schematic is split into 30+ hierarchical sheets and drawn to assist functional understanding. If...
by simoni
Sun Mar 24, 2019 8:08 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

Ok, I've now finished testing and fixed a few things here and there... My testing on both ADFS and VFS now works flawlessly :) I've merged the dev branch and prepared a new release. You can get the 2.5 version from here: https://github.com/simoninns/BeebSCSI/releases/tag/V2.5 The release files inclu...
by simoni
Sat Mar 23, 2019 9:36 pm
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

I've added the additional flush (seems to work now) and moved the other flush commands down a little (so it only flushes if the initial error check is successful) - I've also bumped the firmware version reporting to 2.05 I tested, formatting (using SuperForm), mounting, SCSI jukebox and also ran it ...
by simoni
Sat Mar 23, 2019 3:43 pm
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

I've given the changes some testing and it doesn't seem to work correctly. The firmware is unable to MOUNT any other LUNs; so it works fine until you attempt a *MOUNT to switch to another LUN - then only power-cycling will bring it back to functioning. Looking at the debug traces I can see the follo...
by simoni
Tue Mar 12, 2019 5:19 am
Forum: hardware
Topic: A potential run of BeebSCSI 7.7 (the newest)
Replies: 87
Views: 2910

Re: A potential run of BeebSCSI 7.7 (the newest)

It means that whilst you can't attach the LV-ROM player via a host adapter to the external 1MHz bus and read it in ADFS (you just get a duplicated/triplicated data stream), you can attach an ADFS-formatted SCSI disc to the AIV board and read it in VFS. As I've mentioned elsewhere on this forum in t...
by simoni
Tue Mar 05, 2019 6:53 am
Forum: hardware
Topic: BeebSCSI 7_7
Replies: 115
Views: 4500

Re: BeebSCSI 7_7

dp11 - I appreciate the hard work and I'll look into the pull request shortly.

I'm a bit swamped with work from the ld-decode project at the moment, which is why I'm a bit slow on the BeebSCSI side of things as it's using up 110% of my hobby time just to keep up :)
by simoni
Sun Dec 16, 2018 9:43 pm
Forum: for sale / freebies
Topic: Dutchacorn clearing out
Replies: 29
Views: 2142

Re: Dutchacorn clearing out

Just a note of thanks Paul, your generous donation will be put to good use!

/Simon (of Domesday86)