|
Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment. |
|
Thread Tools |
29th Dec 2017, 5:05 am | #1 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
BBC Master boot
Inspired by the thread about running a BBC into a modern monitor, I have decided to try to get the Master 128 Paul sent over running.
I have got it working through a GBS8200 to an old HP L1502 LCD monitor. I have a number of these that I picked up from a client who was going to put them into ewaste - the same client that I picked up a number of vintage computers from, including a CBM8032, HP 85, Amstrad 6128 and Apple IIe. Anyway, the GBS8200 is doing the job fine so far - it's showing me that the Master is reporting two messages but doesn't appear to be dropping in to BASIC. I am getting: Code:
Acorn MOS Acorn ADFS Going out on a limb, and without much in-depth understanding of BBCs, does this mean that I only have the ADFS ROM and not the BASIC ROM? If that's the case, what ROMs should I keep an eye out for? I've attached a closeup of the message (contrast bumped up a bit in Photoshop, the camera was struggling with the amount of light around on another nice summer's day!), the setup (and messy workshop) and a closeup of the GBS8200. I originally purchased it to run with the Sords, so made up a cable from the converter to a DA15, then DA15 to whatever end the computer needs so I can swap over easily - DA15 seems an odd choice, but I had a heap left over from another project that never really happened.... |
29th Dec 2017, 5:36 am | #2 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
|
Re: BBC Master boot
As it's a Master, most likely the contents of the CMOS RAM are corrupted and it is not looking for the BASIC ROM but looking for a language ROM in some other position.
I seem to remember that you hold down a key at power-on and it will go into the default configuration, including BASIC. But I can't remember what the key(s) is -- ctrl-D perhaps? |
29th Dec 2017, 5:57 am | #3 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Thanks Tony - I've done a little more research, and have found that apparently Ctrl-F was supposed to work to drop me to something more useful - it doesn't, but holding down F while booting seems to do it.
This has raised another issue - I've got a number of keyboard faults, including useful keys like X, C and B. It's quite possible Ctrl is also an issue, although when testing a few of the ones that weren't showing on-screen with a multimeter (after removing the keyboard) I forgot to check that one. Unfortuantely squirting in CRC CO makes no difference, and I can't see how to disassemble the switches. It looks like I'll need to buy a few keyswitches! |
29th Dec 2017, 6:03 am | #4 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,190
|
Re: BBC Master boot
I seem to remember the Master has a numeric keypad. On other machines with such a feature (which is not essential) I have taken good switches from there to get the main part of the keyboard working properly and put the dud keyswitches in the numeric keypad area until I could get replacements.
|
29th Dec 2017, 6:10 am | #5 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Excellent idea! I'll do that in the meantime
|
29th Dec 2017, 8:22 am | #6 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
|
Re: BBC Master boot
Your Master is starting up with ADFS (the Advanced Disc Filing System) as the filing system. The first thing ADFS does is try to mount the disc. With no disc drive present, it will just sit there waiting. I recommend holding down the 'D' key while switching on, or while pressing the BREAK key. That should force the DFS (Disc Filing System) to be selected, which is much simpler and doesn't try to access the disc until you tell it to. That should get you to a BASIC prompt.
Now you can configure the machine because the CMOS RAM probably has junk in it. Type *ROMS to list the ROMs available. Identify which one is 'DFS', then do *CONFIGURE FS with that number. You can shorten *CONFIGURE to *CONF. (note the dot). That should save the preferred filing system in the CMOS RAM. Chris
__________________
What's going on in the workshop? http://martin-jones.com/ |
29th Dec 2017, 12:37 pm | #7 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Thanks Chris. I will swap keyswitches around first - very hard to type configure without a C - and then see how I get on. I completely forgot to grab a battery holder from Jaycar when I got the cable, so will do that next time in town so the configuration data can be saved.
|
29th Dec 2017, 12:49 pm | #8 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,786
|
Re: BBC Master boot
Glad to hear you're making progress of sorts with this. The keyswitches are probably just oxidised as this machine had been unused in my unheated loft for about ten years, and may have also been out of use for at least a decade before that. If you can dismantle them somehow you can probably repair them. I salvaged it for a data conversion job that never materialised.
|
29th Dec 2017, 2:28 pm | #9 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
|
Re: BBC Master boot
I've just tried my own advice (always a good idea) on BeebEm set to Master 128 mode. It turns out that the command you want is *CONFIGURE FILE, not *CONFIGURE FS. I mis-remembered.
I also note that *ROMS lists ROM numbers in hexadecimal, but *CONFIGURE wants them in decimal, unless you prefix them with an ampersand (&). Looking at your screenshot, you might also want to do *CONFIGURE MODE 7 to make it all easier to read! Chris
__________________
What's going on in the workshop? http://martin-jones.com/ |
29th Dec 2017, 2:31 pm | #10 |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
|
Re: BBC Master boot
A further note: try holding down the SHIFT key while you switch the machine on. It's possible that it's configured to try booting from a disc by default, which it won't be able to. In which case *CONFIGURE NOBOOT will fix it.
Chris
__________________
What's going on in the workshop? http://martin-jones.com/ |
29th Dec 2017, 2:56 pm | #11 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,786
|
Re: BBC Master boot
To clarify, when I acquired this machine it came with two floppy drives and some ribbon cable. Andrew decided that he didn't want them sent because of the cost (they are very heavy) and there was no guarantee that they would be serviceable.
I do still have the drives, but they haven't become any lighter. I don't have any floppies. |
29th Dec 2017, 4:05 pm | #12 |
Hexode
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
Posts: 296
|
Re: BBC Master boot
cjemicros.co.uk sell keyswitches for these if they won't clean up. Now I am retired I have recently setup my BBC system after it had laid dormant since the ninety's, one of my switches wouldn't respond to a spray so stripped it down and reassembled it and it works fine now. Arjoll there's loads of stuff out there about BEEBs just google it.
Andrew |
29th Dec 2017, 4:07 pm | #13 |
Dekatron
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,241
|
Re: BBC Master boot
The Master keyswitches always were less reliable than the types used in the previous machines. Luckily for me, a service engineer left an assortment of key switches and other BBC parts in a cupboard at school, and after several failed attempts to reunite the engineer with his parts, the school gave up and let me have them. And this was in 1990, when the machines were relatively young. I don't remember any instances of non-Master keyswitches failing, but I've used up most of the Master ones now. The last Masters used a membrane keyboard, like modern PC keyboards, and these felt rather different, but in a good way.
Once the backup battery has been replaced, hold down R at power-up. This resets the CMOS RAM to a sensible state, and should give you access to a command line where you can type star commands like *ST., *ROMS, *CO., etc. The configuration options are covered in appendix C of the welcome guide - here if you haven't already found it: http://8bs.com/othrdnld/manuals/essentialsmaster.shtml (scroll to the bottom) This is a good excuse to plug this site - https://bbc.godbolt.org/?model=Master# - a BBC emulator written in JavaScript (pretty amazing, really). You can type *ST. there to see a list of sensible defaults... |
29th Dec 2017, 4:25 pm | #14 |
Dekatron
Join Date: Jul 2007
Location: Evesham, Worcestershire, UK.
Posts: 4,241
|
Re: BBC Master boot
Further to the above, I've just tried holding down R while using the drop-down menu in the above JavaScript emulator to generate a hard reset, and it works as expected, coming back with a disc error after a couple of seconds (where your machine hangs because you don't have a disc drive). As suggested above, holding down D while hitting break will set the file system to DFS, so it won't be trying to read the disc catalogue at reset (that also works in the emulator).
That emulator is linked to the BBC Micro disc image archive, so you can spend hours playing around with all the old software. But of course, the next step is to make a serial lead and transfer these images to a real machine. With a floppy disc drive attached (you'll need a double-density type), you can then make discs from those images. It's pretty straightforward once you've got going: http://www.8bs.com/filecon.htm#Xfer Oh, another guide to the CMOS RAM problem: http://8bs.com/artcmos.htm Finally, I have a real Master setup upstairs, so can double-check things for you quickly if needed... Enjoy |
29th Dec 2017, 6:58 pm | #15 | |
Nonode
Join Date: Oct 2008
Location: Warsaw, Poland and Cambridge, UK
Posts: 2,669
|
Re: BBC Master boot
Quote:
Chris
__________________
What's going on in the workshop? http://martin-jones.com/ |
|
29th Dec 2017, 9:52 pm | #16 |
Hexode
Join Date: Jan 2016
Location: Ramsgate, Kent, UK.
Posts: 296
|
Re: BBC Master boot
A worthwhile upgrade for your Master is MOS 3.50, You can check what's in yours with *FX0. I'm pretty sure I have the final version Acorn did, I am able to run a hard drive (Winchester) with mine. There are lots of useful additions, R Break (discussed above) puts a set of sensible values in the battery backed CMOS RAM. One way of telling if you may have the later version is do a *h. , the 'Advanced DFS' reports itself as '2.04' , earlier version of MOS 3.50 report '2.03'. Oh and though not guaranteed to be compatible with all software it runs Elite OK....Phew!!
Andrew |
30th Dec 2017, 3:45 am | #17 | |||
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Thanks everyone for the advice on this - I should have known that there would be a ton of information on BBCs out there!
Quote:
Next step is to pull the keypad ones and use them on the main keyboard to get things running. Without useful keys like C and B, I had no way of getting the commands suggested here into the machine! Quote:
Quote:
I've found a seller on eBay who has them for GBP2 plus postage - so maybe later in the year once the credit card has recovered from Christmas and getting the kids settled back in university. |
|||
30th Dec 2017, 4:41 am | #18 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Another quick update. I figured I had nothing left to lose with the keyswitches, so carefully tried opening one up - they definately appear to be glued or fused together - photo 1 shows what happens with 30 year old plastic when you try to undo what appears to be a clip which turns out to be stuck to the black plastic it is "clipped" to!
At this point I really did have nothing left to lose, so referred to some information I found yesterday here about a Memotech keyboard which uses the same Futaba keyswitches. It detailed how the pins screw out (around two turns anticlockwise), so I tried that, squirted some CRC CO into each hole, worked the mech and then reinserted the legs. Turns out that it works! I now have 11 keyswitches that give a nice clean contact, and one that's a little scratchy, which will go back into the keypad. I am not sure how long this fix will last, but in the meantime it has saved me spending GBP30.50 including shipping on 12 NOS keyswitches - and also is a technique I'll remember if any others start failing. Photos - switch with broken clip, switch with one pin removed, switch after a couple of squirts of CO (in a small pool of CO, it evaporates pretty quickly), and the magic spray itself - works brilliantly on the switches in Akai tape recorders too |
31st Dec 2017, 12:24 am | #19 |
Octode
Join Date: Nov 2004
Location: Hebden Bridge, West Yorkshire, UK.
Posts: 1,885
|
Re: BBC Master boot
I've had only one bbc master keyswitch die, they nearly always respond to repeated hammering after a dose of servisol. I think they suffer from tarnishing which quickly rubs away.
|
31st Dec 2017, 3:41 am | #20 |
Dekatron
Join Date: May 2006
Location: Invercargill, New Zealand
Posts: 3,440
|
Re: BBC Master boot
Latest update. I've grabbed a small 4x AAA holder from Jaycar (they don't do 3xAA and this seemed the best option) and now have a configuration that stays. I've got it defaulting to booting into BASIC and what appear to be some sensible defaults set.
Next quesion - the machine came with two ROM cartridges. Both had two EPROMS - one a 27128 labelled "RAMROD" and an unlabelled 27256, the other two unlabelled 27256s. All except "RAMROD" had nothing covering the window. I have now stuck some some silver floppy disk write protect labels over the windows. I'm not sure how quickly EPROMs can be erased with nothing over the windows, but they only came out of the bag they were sent in for a few seconds at a time, and never outside in Southland's high UV environment. With these inserted, I either get garbage on boot, or three additional ROMs showing up:
ROM 1 (presumably the 27256 in the same cartridge as RAMROD) is showing ?. With the cartridges installed, I notice the Master locks up quite frequently, but BREAK will reset it. Should I assume the content of these EPROMs has been scrambled by the blank windows and/or old age, or if not is there some way to find out what they are? Do the names seem familiar? I am getting a good display and colour through the GBS8200 - the only complaint is that I have to reset the geometry when changing modes, although haven't identified that if it is just mode 7 that is different or if all of them have other differences. The picture is nice and clear, no shimmering, and it's only using around 450 mA through my bench supply so the reports of the converter needing a 2A supply seem to be false (although I have a spare 5V 2A supply I'll be using on it anyway). Caps Lock doesn't appear to work, but it was one of my repaired keyswitches so I suspect the repair didn't "take." I'll swap it with something on the keypad or maybe Shift Lock. Getting used to the UK keyboard will be interesting, I'm used to " being shift-2 and * being shift-8, and have no use for a pound key! Other than that, I believe I have a working Master. Thanks to everyone for their help, especially Paul Sherwin for fishing it out and sending it over! |