Search found 188 matches

by JannievanZyl
Mon Jun 25, 2018 10:25 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

Thanks for the info Chris! So it looks like the Model B defaults to 24ms step time and the Master to 6ms which is closer to what the drive specs say? This is probably because the Model B had a default configuration for an 40-track drive and the Master for an 80-track? So, on the Master I'll leave it...
by JannievanZyl
Mon Jun 25, 2018 10:15 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

As others have suggested, RAM faults would normally give vertical blocks, not diagonal. This is making me suspect something other than the RAM is at fault (or also at fault). Thanks Kazzie and others. I'll get back to this machine in the next day or so and think I'll retake some good quality photos...
by JannievanZyl
Mon Jun 25, 2018 8:46 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

I found this table of the init jumpers on the keyboard in the DFS manual.

Since, the drives in my setup are Mitsubishi drives, should I make Link-4?

Will it improve performance, reliability, etc?
keyboard jumpers.JPG
Oh, and...on the BBC Master, are these same settings available?
by JannievanZyl
Mon Jun 25, 2018 3:31 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

MartinB wrote:
Mon Jun 25, 2018 3:22 pm
The jumpers seem to be immediately adjacent to what looks like a 150 ohm resistor array so I suppose it is highly likely that they are in some way associated with termination enabling.
Sharp eyes!, just saw that now. Think you might be right!
by JannievanZyl
Mon Jun 25, 2018 1:01 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

In the pic below, the bank of installed jumpers on the floppy drive (middle, right); I cannot find these in the drive's documentations.

Could those be for enabling the terminator on the data cable?
Capture.JPG
by JannievanZyl
Mon Jun 25, 2018 12:57 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

danielj wrote:
Mon Jun 25, 2018 8:26 am
I for one am forever amused that 3.5" discs in SA are called stiffies. I am also a child. *proud*
:)

Just think if we called our 8" disks, 'Stiffies'....tourists would be too scared to come visit!! :)
by JannievanZyl
Mon Jun 25, 2018 8:17 am
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

Thanks guys!

/Off to try more things and read some more. :)
by JannievanZyl
Sun Jun 24, 2018 10:35 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

Hi, 1) The M4853 is 80T double sided. 2) I assume the 3.5" is 80T... I've never seen one that isn't 3) DFS and ADFS are two rather different filing systems and are incompatible. DFS is older and simpler, has short filenames, 31 (IIRC) files per side. Disk sides are treated as separate drives. ADFS ...
by JannievanZyl
Sun Jun 24, 2018 9:14 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

Some questions (and I'll be Googling like crazy but thought to ask so long); 1. Is the M4853 floppy drive 40 or 80 track? 2. Is the NEC FD1037A drive 40 or 80 track? 3. Is there a difference between using DFS and ADFS? I.e. do they format disks differently? Must I switch between the two modes (DFS/A...
by JannievanZyl
Sun Jun 24, 2018 9:00 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Re: Floppy / Stiffy Drive setup

The unit itself consists of 3 drives; Two Mitsubishi M4853 5.25" floppy drives and one NEC FD1037A 3.5" stiffy drive. These seems to configured that a switch can select either the one 5.25" or the 3.5" drive as Drive 0/2 with a toggle switch. unit-1.jpg Switch.jpg floppy.jpg stiffy.jpg I've got this...
by JannievanZyl
Sun Jun 24, 2018 8:56 pm
Forum: hardware
Topic: Floppy / Stiffy Drive setup
Replies: 21
Views: 512

Floppy / Stiffy Drive setup

So, I got given a floppy drive setup with 2 x 5.25" floppies and 1 x 3.5 stiffy drive. Initially I could not get it to do anything on Floppy 0 and after a bit of faultfinding found that one of the pins on the ribbon cable to Floppy-0 was dis. Turns out it was the actual vampire tap in the edge conne...
by JannievanZyl
Sun Jun 24, 2018 1:05 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

marcusjambler wrote:
Sat Jun 23, 2018 9:09 pm
If the Mode 7 screen is corrupt then it could be IC5 SAA5050 Teletext Character Generator causing issues.
Was wondering about that.

Could it also be that the 1KB of RAM Mode 7 use could have some issue? Does it sit as the 1st 1KB of the bottom 16KB block?
by JannievanZyl
Sat Jun 23, 2018 5:17 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

1024MAK wrote:
Sat Jun 23, 2018 4:41 pm
Info on link S26 in this thread :wink:

Mark
Thanks Mark,

The thing I love about these old computers is that every machine has got so many intricacies. And the cool bit is learning about each of them. :)
by JannievanZyl
Sat Jun 23, 2018 4:17 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

1024MAK wrote:
Sat Jun 23, 2018 4:04 pm
S26 on or off depends on which version of the VideoULA/Video Poccessor you have fitted. It affects teletext mode.

Mark
Thanks Mark,

Do you know which model of the ULA should have S26 in which position?
by JannievanZyl
Sat Jun 23, 2018 2:41 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Glad your getting closer. Looks like one or two bits aren't being read/written correctly in the first half and maybe some address line related blocks stuck on zero in the top half. Maybe A7. Good luck. Thanks Tricky, Looking at the screen shots of the diagonal lines, are those gaps caused by missin...
by JannievanZyl
Sat Jun 23, 2018 2:38 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

It is odd that you do get different behaviour in the graphical mode, but not in mode 7. No change at all? There might well be a difference in the Mode 7 screen but it's so corrupted and comes and goes so quickly that I cannot make any clear statements on it. I also think that the fact that the "dia...
by JannievanZyl
Sat Jun 23, 2018 1:48 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

That looks like progress! Any variation between S25 north / south / removed settings? Not on the 'Frogger' screen, no. But I can see changes in the bit patterns being displayed with S25 moving. This is in North: north.jpg This is in South: south.jpg And this is Open open.jpg . It looks like I've go...
by JannievanZyl
Sat Jun 23, 2018 12:57 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

If I pull S26 completely off (it was left), I get this;
Faulty-Frogger-2.jpg
/Off to go and read exactly what S26 does. Just assumed it inverts something as per the pin description.
.
/Added: Looks like S26 should not be mode on an Issue 7 board. Someone clearly fiddled before me.
by JannievanZyl
Sat Jun 23, 2018 12:46 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

OK, now that I know I've got a working Test ROM (how crazy was that whole process? :) ), With a working set of the big chips and the Test ROM now flashing LEDs and doing the sounds, etc. this is the how the Frogger screen looks; Faulty-frogger.jpg I get this with a known good CRT controller and irre...
by JannievanZyl
Sat Jun 23, 2018 12:24 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Halle-EFFING-lujah.... :)

Wrote another ROM and this one works.... =D>

Now I can actually get back to looking for actual faults. :)
by JannievanZyl
Sat Jun 23, 2018 12:05 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

I've now pulled out a Beed I fixed before and played a games on, so I'm pretty sure it's fine.

But I get the same non-frogger screen. So I first need to figure this out before I can carry on fixing actual broken
Beebs. :)
by JannievanZyl
Sat Jun 23, 2018 10:55 am
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Did all these Beebs come from the same place? Get used with the same CRT monitor maybe? Although there's other circuitry between the various video output sockets and the CRTC... They were two batches of two and three systems each. But I have no real history on them. One thing to note: not all CRTC ...
by JannievanZyl
Fri Jun 22, 2018 10:52 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Related question;

How often do do you guys find the CRT controller (IC2) failing?

Out of the last 5 Beebs that came past here, 4 of them have faulty CRT controllers.

Any views on this and - more importantly - where can I get a handful of them? :)
by JannievanZyl
Wed Jun 20, 2018 12:15 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

I think I only posted the version in the thread linked above which does the mode 7+LEDs+relays+sound, then goes into mode 0 for but checking. Making it more sophisticated and adding error reporting are on the list, it will probably get a version and who knows maybe a checksum if I every get time. F...
by JannievanZyl
Wed Jun 20, 2018 12:12 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Sorry for being persistent but.... I can only guess that a real beeb is not reading your EPROM correctly. Did you ever only make the one version of the Test ROM? I'm not maybe burning an older, beta version? These are compelling reasons for using a checksum. How about testing the programmer by burn...
by JannievanZyl
Wed Jun 20, 2018 10:43 am
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

marcusjambler wrote:
Tue Jun 19, 2018 10:38 pm
How about testing the programmer by burning a copy of BASIC and seeing if it boots on the working beeb
Good idea.
by JannievanZyl
Wed Jun 20, 2018 10:42 am
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

I can't think why it wouldn't work on a working beeb, maybe a master if the CPU and GPU were using different shadow ram. I'm guessing that you don't have anything exotic installed. I can only guess that a real beeb is not reading your EPROM correctly. Yeah, I'm going to dig out another beed and tes...
by JannievanZyl
Tue Jun 19, 2018 9:46 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

Must say, I've never seen those screens, even on my "working" Beebs... :o
by JannievanZyl
Tue Jun 19, 2018 9:38 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

OK, just got it working in beebem.....

....baby steps....
by JannievanZyl
Tue Jun 19, 2018 9:36 pm
Forum: hardware
Topic: (Yet another) Memory Question
Replies: 69
Views: 1575

Re: (Yet another) Memory Question

just a 27128 that I had lying around. Does your image work in beebem or any emulator for that matter? You can get it in the thread linked above. Sometimes it feels like you take a step forward and two back.... Just installed beebem but when I select the tester ROM as the OS ROM (I assume this is wh...