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by jgharston
Sun Sep 24, 2017 3:45 pm
Forum: off-topic
Topic: VOT: To let
Replies: 0
Views: 2

VOT: To let

Very off topic... In a couple of months I'll have tenants leaving, so will have a flat and (hopefully) a house to let in Sheffield. I'll be advertising them when they are vacant and available. Spacious unfurnished two/three-bedroom first-floor flat on South Road, Walkley : http://mdfs.net/User/HWPS/...
by jgharston
Sun Sep 24, 2017 11:24 am
Forum: hardware
Topic: BBC B / Datacentre Fault
Replies: 12
Views: 137

Re: BBC B / Datacentre Fault

danielj wrote:I really recommend dropping ...

On reading the first few words I fully expected it to continue: your machine from about one inch onto the desk. Sometimes a quick fix for intermittantly socketed ICs.
by jgharston
Sun Sep 24, 2017 11:21 am
Forum: hardware
Topic: 5 pin din domino pcb mount sockets
Replies: 19
Views: 513

Re: 5 pin din domino pcb mount sockets

I'm very strongly tempted to recommend you use a standard 9-pin D connector. I've many times been tempted to replace the 5-pin domino on my Beebs with a 9-pin D.
by jgharston
Sat Sep 23, 2017 12:43 am
Forum: hardware
Topic: Master CMOS checksum
Replies: 4
Views: 179

Re: Master CMOS checksum

dominicbeesley wrote:Thanks JGH, I was misremembering "Bad Sum" as being config rather than ADFS...it's my age

Hey, I can barely remember what I was doing when I... what was I saying?
by jgharston
Fri Sep 22, 2017 2:08 am
Forum: hardware
Topic: Master CMOS checksum
Replies: 4
Views: 179

Re: Master CMOS checksum

dominicbeesley wrote:I've been trying to figure out how the Master 128 checksums its CMOS settings.

The 8-bit systems don't checksum the CMOS, only the ARM systems do and even then not all of them. Location 50 doesn't hold a checksum, location 50 is just another location on systems that have more than 50 locations.
by jgharston
Fri Sep 22, 2017 1:55 am
Forum: hardware
Topic: Startup sequence/timing
Replies: 4
Views: 180

Re: Startup sequence/timing

I seem to remember reading in the service manual how long the 555 startup timer holds RESET on a power-on before letting the CPU go. Checking the circuit diagram and dredging up 'O' level electronics gives: Power-On RESET is an RC network of 1M x 10nF so 0.01s to reset the system VIA Break-RESET is ...
by jgharston
Thu Sep 21, 2017 3:36 am
Forum: software: other
Topic: Are there versions of BBC Basic with extensions (like procedures)
Replies: 10
Views: 314

Re: Are there versions of BBC Basic with extensions (like procedures)

To reinforce what other people have already said, BBC BASIC has AWAYS had procedures, I can't understand how somebody could have managed to actively prevent themselves from noticing this. Naturally, there's a description of the different functionality of different versions of 6502 BBC BASIC on the W...
by jgharston
Mon Sep 18, 2017 10:23 pm
Forum: hardware
Topic: Resurrecting A5000
Replies: 41
Views: 1043

Re: Resurrecting A5000

Are batteries more likely to leak with the power on or the power off? The MDFS has only been powered down for a few hours since 2011 when I did some rewiring in the cellar.
by jgharston
Mon Sep 18, 2017 7:03 pm
Forum: hardware
Topic: Resurrecting A5000
Replies: 41
Views: 1043

Re: Resurrecting A5000

Jonathan - have you taken the batteries out of your MDFS? (before anything else gets zapped!) There's batteries in my MDFS? Well, yes of course there's _a_ battery. When I last had everything dismantled and took the lid off I took some photos of the inside , and everything looks fine, and the batte...
by jgharston
Mon Sep 18, 2017 6:53 pm
Forum: other vintage computer hardware, software and games
Topic: Spectrum Currah MicroSource
Replies: 5
Views: 96

Re: Spectrum Currah MicroSource

Is this it: currah.rom?

With my RISC OS system offline I'm not able to dig into my files much.

Edit: ah, the microSOURCE not the microSPEECH. ;)
by jgharston
Mon Sep 18, 2017 2:09 pm
Forum: hardware
Topic: Resurrecting A5000
Replies: 41
Views: 1043

Re: Resurrecting A5000

Well, that's the temporary replacement A4000 also up the futz. Yesterday I'd just finished zipping up the lastest website update when something went Fzzzzttttz and it died.
by jgharston
Tue Sep 12, 2017 12:51 am
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4305

Re: 6809 experiments

I'm just sorting a few bugs out from when I started and I though that LDA B,X on the 6809 did the same as LDA ($xx),Y but it doesn't it treats B as 2's complement! (I'm not alone, I think JGH managed to get tripped by that too!). Yes, doing 256-byte language transfer doesn't really work when you st...
by jgharston
Tue Sep 12, 2017 12:48 am
Forum: hardware
Topic: Resurrecting A5000
Replies: 41
Views: 1043

Re: Resurrecting A5000

With my A5000 temporarily (I hope) dead, I've got the drives in an A4000. I've been using it to back up the server. Yea gods, the A4000 is slow. I take it the A4000 is the Acorn Electron of the RISC OS world. A compatible machine but with all the memory access crippled. Normally, I zip up the server...
by jgharston
Sun Sep 10, 2017 10:31 pm
Forum: hardware
Topic: 6809 experiments
Replies: 109
Views: 4305

Re: 6809 experiments

Is there any reason it shouldn't work on the Matchbox and/or PiTubeDirect? I remember there was some discussion a few weeks ago about changing some of the 6809 Tube Client ROM APIs. I don't remember what the outcome was. It should work directly on the MatchBox and Pi, and that's what I've been test...
by jgharston
Sun Sep 10, 2017 10:21 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 23
Views: 417

Re: Using BBC BASIC to teach programming concepts in 2017

Some students will only ever want (and maybe need) a superficial understanding of programming, instead just needing to "get things done on the computer". ... Other students will want to "get the computer to do things". ... In teaching at all levels there seems to be a confusion ...
by jgharston
Sun Sep 10, 2017 10:11 pm
Forum: archive submissions
Topic: Fileserver software
Replies: 4
Views: 148

Re: Fileserver software

the level 2 discs seem to be on 8BS? http://www.8bs.com/econet.htm Ah yes, right. Looks like only the utilities though, not the master disk, unless I'm reading that wrong. I'll see if I can figure out a way to image the SJ ones. They are 1024bytes x 5 sectors x 2 sides x 80 tracks, as with 800K ADF...
by jgharston
Sun Sep 10, 2017 7:29 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 23
Views: 417

Re: Using BBC BASIC to teach programming concepts in 2017

You can probably guarrantee that whenever there's some news item with somebody saying "Schools should teach X", my immediate response is: "what, you mean they don't? as in don't any more? they did when I was at school".
by jgharston
Sun Sep 10, 2017 7:25 pm
Forum: software: other
Topic: Slow OSBGET file access
Replies: 8
Views: 230

Re: Slow OSBGET file access

My assumption was that a disk-based file system would have a 256 byte buffer somewhere, but I don't have any evidence to support that. It's a valid assumption and supported by the fact that PAGE is at &1900 in a DFS machine, and explained in all and any documentation as because there are buffer...
by jgharston
Sun Sep 10, 2017 3:02 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 23
Views: 417

Re: Using BBC BASIC to teach programming concepts in 2017

Oddly enough, when I took driving tests in America, Saudi Arabia and Scotland there was no exam about how internal combustion engines and their associated electronics work . . . When my car starts misbehaving I take it to a mechanic who (one hopes) knows what s/he's doing to sort the thing out. he....
by jgharston
Sun Sep 10, 2017 2:59 pm
Forum: off-topic
Topic: Using BBC BASIC to teach programming concepts in 2017
Replies: 23
Views: 417

Re: Using BBC BASIC to teach programming concepts in 2017

I think it's the same with education across the board. Do citizenship lessons teach you how to pay gas bills or lay mousetraps - things you'd need in the real world? I don't quite recall it when I was there. During my 'O' level years we had "Design For Living" which taught us exactly that...
by jgharston
Sun Sep 10, 2017 2:41 pm
Forum: software: other
Topic: TCP/IP for Econet
Replies: 3
Views: 175

Re: TCP/IP for Econet

Continuing my trawl through old disks, I uncovered the source code to an implementation of TCP/IP that I wrote for the BBC in about 1995. It speaks the same wire protocol as EconetA. In case anybody is interested I have put the source on github: https://github.com/philb/bbc-iprom Back in the 1990s ...
by jgharston
Sun Sep 10, 2017 2:35 pm
Forum: software: other
Topic: DFS - Get sector for a file
Replies: 13
Views: 753

Re: DFS - Get sector for a file

jgharston wrote:I can't post the code from where I am, but here's a demo:
http://mdfs.net/temp/MVI_0073.AVI

I should have posted the code for that. I'll dig it out.
by jgharston
Fri Sep 08, 2017 1:07 pm
Forum: hardware
Topic: Z80 co-pro, and datacentre?
Replies: 99
Views: 6759

Re: Z80 co-pro, and datacentre?

Do the instructions in the README file not work? I'm fairly certain that everything that is supposed to be in RFSTools.[zip|ssd] is there. This one here , yes? I was using the instructions posted earlier in the thread... A post made two-anna-half years ago in a discussion of "here's something,...
by jgharston
Fri Sep 08, 2017 1:38 am
Forum: hardware
Topic: Z80 co-pro, and datacentre?
Replies: 99
Views: 6759

Re: Z80 co-pro, and datacentre?

First post on the forum and a bit late to the discussion! I have downloaded RFSTOOLS following the instructions from jghartson, but the 'dsktrap' file seems to be missing? Do the instructions in the README file not work? I'm fairly certain that everything that is supposed to be in RFSTools.[zip|ssd...
by jgharston
Mon Sep 04, 2017 8:44 pm
Forum: software
Topic: Undelete
Replies: 5
Views: 295

Re: Undelete

DisKnight!
by jgharston
Mon Sep 04, 2017 12:53 am
Forum: hardware
Topic: VT Clock Rom
Replies: 3
Views: 146

Re: VT Clock Rom

Functionally it will be very similar to VTClock as video clock titles have a standard layout and content demo here.
by jgharston
Sun Sep 03, 2017 5:54 pm
Forum: introduce yourself
Topic: Archie Noob. Completed Restoration and could use some help
Replies: 47
Views: 854

Re: Archie Noob. Completed Restoration and could use some help

If its not there, you'll possibly need to also type: *Configure harddiscs 1 HardDiscs changes the number of ST506 disks you have IDEDiscs changes the number of IDE disks you have IDEFSDiscs changes the number of external IDE interface disks you have. If you run Apps->Configure it will display the d...
by jgharston
Sun Sep 03, 2017 12:40 am
Forum: hardware
Topic: Resurrecting A5000
Replies: 41
Views: 1043

Re: Resurrecting A5000

A few months ago the battery gave out on my A5000, so I resorted to saving the configuration settings and R-Power'ing and reloading them. Last week the hard drive stopped working, just as described above, which is why I've not been updating CoPro stuff much, having to transfer stuff between the PC a...
by jgharston
Sun Sep 03, 2017 12:28 am
Forum: hardware
Topic: Another A5000
Replies: 17
Views: 374

Re: Another A5000

Is that corrrect? Yes, in theory. I ran my A5000 with no battery for several months, just holding Delete each time at switch-on. You need to reconfigure the HDD each time and set the clock, but that's it. A useful thing to do is, once you've got it configured the way you want, is save the configura...
by jgharston
Sat Sep 02, 2017 6:18 pm
Forum: software: other
Topic: more explaining please :)
Replies: 3
Views: 221

Re: more explaining please :)

duikkie wrote:almost i get it :) but..
why is b7 chr$32-63 was it not locial b7 224,255 ?? b0 for 0-31 vdu , b1 for 32-63 and so on ??
Probably to save a few bytes in the ROM code. The font bitmap table is the same table as the 4-colour screenmode pixel map.

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