Search found 171 matches

by scarybeasts
Tue Jan 07, 2020 11:46 pm
Forum: software: classic games
Topic: Demystifying Nightworld
Replies: 18
Views: 1004

Re: Demystifying Nightworld

This may be a form of blasphemy, but could you cheat your way over the gap, and then at least get to see what the fleece actually does? I'm totally not above it at this point given I feel I've discharged my core obligation to the game. Fancy helping? :) I'd be happy to try and help if no-one else h...
by scarybeasts
Fri Jan 03, 2020 6:57 pm
Forum: software: classic games
Topic: An Exile writeup
Replies: 14
Views: 687

Re: An Exile writeup

- Opening the rune door. It's stated a couple of times that the only way is a coronium explosion, but "enough" grenades will also do it semi-reliably. It's hard to say if this is a glitch or not (i.e. falls under your definition of fair play), but I think it might be ok because it's just a way of c...
by scarybeasts
Fri Jan 03, 2020 5:12 am
Forum: software: classic games
Topic: An Exile writeup
Replies: 14
Views: 687

Re: An Exile writeup

Hi Bill, Thanks for putting this together -- it's exceptional and very well presented! I may have to relinquish my claim to be Exile's biggest fan. I think you've got pretty much everything I ever found: https://scarybeastsecurity.blogspot.com/2014/09/exile-for-bbc-micro-some-elegant.html Here are s...
by scarybeasts
Tue Dec 31, 2019 3:15 am
Forum: introduce yourself
Topic: Hello from California
Replies: 14
Views: 873

Re: Hello from California

A belated welcome, Steve!

I'm also a transplant to California. I wonder if there's enough of us now for a California ABUG? (ABUG in the sun? :D)


Cheers
Chris
by scarybeasts
Tue Dec 31, 2019 3:13 am
Forum: emulators
Topic: Interesting idea for an emulation technique?
Replies: 7
Views: 453

Re: Interesting idea for an emulation technique?

Hi,

An interesting idea -- I'm curious what the overall goal of such an emulation model would be? Would it be insane speed, or something else such as e.g. modern anti-aliased font rendering?


Cheers
Chris
by scarybeasts
Tue Dec 31, 2019 3:07 am
Forum: software: classic games
Topic: Demystifying Nightworld
Replies: 18
Views: 1004

Re: Demystifying Nightworld

Thanks for posting this Ed -- I really enjoyed the read!

Would reverse engineering the code reveal any potential additional secret passages?


Cheers
Chris
by scarybeasts
Sat Dec 21, 2019 10:41 pm
Forum: hardware
Topic: My "new" 5.25 drive -- recognizable symptoms / situation?
Replies: 12
Views: 422

Re: My "new" 5.25 drive -- recognizable symptoms / situation?

To close this out: I confirm that the "shoulder-y" peaks are representative of misalignment. Here's what the Exile disc looks like with better alignment (and it loads): Exile_40_80T_working.JPG I guess the shoulders are now droopy enough not to interfere with the signal. I also found that twiddling ...
by scarybeasts
Sat Dec 21, 2019 7:36 am
Forum: hardware
Topic: My "new" 5.25 drive -- recognizable symptoms / situation?
Replies: 12
Views: 422

Re: My "new" 5.25 drive -- recognizable symptoms / situation?

Ok, this _is_ a drive alignment issue. Re-alignment seems to be VERY sensitive so I'm not 100% done but I do have 2 out of 3 of my 40/80T Exile discs loading now. This particular drive has an optical track 0 sensor that you can move, but finer granularity can be achieved by unscrewing and rotating t...
by scarybeasts
Fri Dec 20, 2019 7:29 am
Forum: hardware
Topic: My "new" 5.25 drive -- recognizable symptoms / situation?
Replies: 12
Views: 422

Re: My "new" 5.25 drive -- recognizable symptoms / situation?

I don't think this is necessarily true for original factory duplicated games. I thought most 40/80 loaders double stepped on 80T drives on a 40T disc - since an 80T head will read a 40T track no problem. Hence why there was so much Master and B+ incompatibility because they assumed the 8271 disc in...
by scarybeasts
Fri Dec 20, 2019 5:33 am
Forum: hardware
Topic: My "new" 5.25 drive -- recognizable symptoms / situation?
Replies: 12
Views: 422

Re: My "new" 5.25 drive -- recognizable symptoms / situation?

Thanks for the thoughtful response! Couple of notes inline: The output of the MC3470AP should be fairly "digital" , (with allowances for a low scope sampling rate) as it'll be handed over to TTL circuitry. The first readout looks reasonable to my eye, but the voltage of the second is, as you say, fa...
by scarybeasts
Fri Dec 20, 2019 3:56 am
Forum: hardware
Topic: My "new" 5.25 drive -- recognizable symptoms / situation?
Replies: 12
Views: 422

My "new" 5.25 drive -- recognizable symptoms / situation?

Hi, I've recently acquired a 5.25" drive. It's just a basic 40T single-sided drive. It is branded "Broadway Electronics" and inside is a Chinon F-051MD. It appears to be surprisingly clean, with springs still springy, clean head surface, no capacitor leakage etc. DFS-0.9 and i8271. I had been having...
by scarybeasts
Wed Nov 06, 2019 6:36 am
Forum: wanted
Topic: Wanted: Cascade Cassette 50 (Electron)
Replies: 18
Views: 761

Re: Wanted: Cascade Cassette 50 (Electron)

Great to see the final pieces being added to a set! Thanks for sharing the picture :)
by scarybeasts
Fri Nov 01, 2019 5:12 am
Forum: hardware
Topic: 1MHz clocks phase difference causing non-deterministic software execution
Replies: 10
Views: 638

Re: 1MHz clocks phase difference causing non-deterministic software execution

scarybeasts wrote:
Thu Oct 31, 2019 10:34 pm
Does anyone own a Master and a scope? I want to know if this phase shift was "fixed" or not. Perhaps this is an investigation for ABUG South!
.... and also needs testing on some model B issue 7s. All of my results are with an issue 3.


Cheers
Chris
by scarybeasts
Thu Oct 31, 2019 10:34 pm
Forum: hardware
Topic: 1MHz clocks phase difference causing non-deterministic software execution
Replies: 10
Views: 638

Re: 1MHz clocks phase difference causing non-deterministic software execution

So Chris (scarybeasts) which pins were you “‘scoping”? system 1MHz is from ADC (NEC D7002) pin 2. (This is for convenience, it's identical to system VIA pin 25 aka. CLK.) 6845 1MHz is from CRTC (Hitachi 6845) pin 21 aka. CLK, while in MODE 7. The 6502 vs. 6845 2MHz signals are also out of phase. At...
by scarybeasts
Thu Oct 31, 2019 9:29 pm
Forum: hardware
Topic: 1MHz clocks phase difference causing non-deterministic software execution
Replies: 10
Views: 638

Re: 1MHz clocks phase difference causing non-deterministic software execution

Try changing the clock rate in the ULA fast->slow->fast. You might be able to get the 1MHz CLK to the 6845 to invert if the timing is right. Different ULA versions might have different behaviour. I didn't get it to invert (and I can't quite imagine how it would), but I can generate a funny double-p...
by scarybeasts
Thu Oct 31, 2019 9:25 pm
Forum: hardware
Topic: 1MHz clocks phase difference causing non-deterministic software execution
Replies: 10
Views: 638

Re: 1MHz clocks phase difference causing non-deterministic software execution

Clock signals for the microprocessor are produced by a 16 MHz crystal oscillator (IC43) in conjunction with divider circuitry in part of the video processor (IC6) which produces 8, 4, 2 and 1 MHz signals. The 1 MHz signal coming directly from the video processor is only used for the Teletext genera...
by scarybeasts
Wed Oct 30, 2019 11:01 pm
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Re: Request for testers for quick but fascinating test case

In case anyone was interested in why the same machine would differ in behavior from boot to boot, I think I worked it out. I was curious enough to buy a simple scope. Turns out there's a very interesting hardware quirk. I've given the details in this new thread in hardware: https://stardot.org.uk/fo...
by scarybeasts
Wed Oct 30, 2019 10:58 pm
Forum: hardware
Topic: 1MHz clocks phase difference causing non-deterministic software execution
Replies: 10
Views: 638

1MHz clocks phase difference causing non-deterministic software execution

Hi, This hardware thread can be seen as a continuation of the emulator thread: https://stardot.org.uk/forums/viewtopic.php?f=4&t=18001 In that thread, we were testing a little test case that timed an interrupt arriving. We observed a lot a differing results, including similar machines giving differe...
by scarybeasts
Wed Oct 23, 2019 2:39 am
Forum: programming
Topic: BBC b, reading the CRT vertical sync position.
Replies: 13
Views: 1446

Re: BBC b, reading the CRT vertical sync position.

At the recent ABUG Cambridge, Jonathan Griffiths' talk was described his use of this technique in Rocket Raid :-)


Cheers
Chris
by scarybeasts
Mon Oct 21, 2019 11:33 pm
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 37
Views: 1223

Re: Calculating digits of Pi in Basic

Yes, paste from clipboard was a big help. But I made the tactical error of pasting the Sharp Basic original and then fixing it up within JSBeeb, instead of working on a master copy and re-importing it. So the other half of the function, copy-from-printer, would be very handy. This was such a good i...
by scarybeasts
Mon Oct 14, 2019 7:33 pm
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 37
Views: 1223

Re: Calculating digits of Pi in Basic

Perhaps *SPOOL to the copy/paste buffer, or into a little text area from which one could copy and paste? If not *SPOOL, then capture the RS432 output... for which we need to know some *FX trickery. But wait: the OS supports a printer, and control-B enables it, so how about capturing that output int...
by scarybeasts
Mon Oct 14, 2019 4:23 am
Forum: software: other
Topic: Calculating digits of Pi in Basic
Replies: 37
Views: 1223

Re: Calculating digits of Pi in Basic

BigEd wrote:
Sun Oct 13, 2019 10:48 am
I'd like to, but I'd need to type it in... that's a drawback of experimenting in JSBeeb.
What do you think jsbeeb could offer to make this sort of thing easier?


Cheers
Chris
by scarybeasts
Mon Oct 07, 2019 5:47 pm
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Re: Request for testers for quick but fascinating test case

It boils down to whether the disc drive ribbon cable is plugged into the disc drive port at power-on or not: Plugged in: 2/1 Not plugged in: 1/1 Changing this (ie. plugging or unplugging the cable) whilst powered on makes no difference to the result, it is the same from power on until the next powe...
by scarybeasts
Sat Oct 05, 2019 5:33 am
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Re: Request for testers for quick but fascinating test case

I'll try Station 129 (BBC Model B issue 2) over the weekend, it's currently having a rest whilst its space is being occupied by my 2 A4000s which are being saved for the nation after 9 years of battery leakage in storage. Issue 2!!! What a beauty. Not sure if this picture I found is it or not but i...
by scarybeasts
Fri Oct 04, 2019 3:24 pm
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Re: Request for testers for quick but fascinating test case

FWIW on my Issue 4 Beeb, I also get 1/1 Thanks! If you happened to know what type of 6522 VIAs it has, that's also useful information! If anyone had any of these configurations, they'd be super useful to test: 1) More issue 3s, any type of 6522 VIA. 2) An issue 7, with non-Rockwell 6522 VIA (did an...
by scarybeasts
Thu Oct 03, 2019 6:50 pm
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Re: Request for testers for quick but fascinating test case

Issue 7 model B 2 CYCLE STRETCH:1 3 CYCLE STRETCH: 1 Thanks Chris. That's definitely different to this issue 3, which is giving an answer of 2 / 1. I must admit, 1 / 1 was not expected, if anything I was expecting 2 / 2. I'll need to go away and think about this. More model B test results welcomed!...
by scarybeasts
Thu Oct 03, 2019 5:51 pm
Forum: emulators
Topic: Request for testers for quick but fascinating test case
Replies: 36
Views: 1739

Request for testers for quick but fascinating test case

Hi, We've uncovered a strange test result on an issue 3 model B that might represent a change in hardware cycle stretching behavior between earlier and later B's. But it's unclear. Anyone able to run a small test on any BBC (issue anything, B, Master, etc.) and share results would be really helping,...
by scarybeasts
Thu Sep 26, 2019 8:15 pm
Forum: wanted
Topic: Wanted: map and clues sheet for BBC Exile
Replies: 7
Views: 653

Re: Wanted: map and clues sheet for BBC Exile

Hi,

Just bumping this thread.

I now have a copy of the clue sheet thanks to a generous gift at ABUG.

So now I'm just looking for a copy of the map. Willing to buy, trade, negotiate emulator features (jsbeeb), donate to the Centre of Computing History, etc.


Cheers
Chris
by scarybeasts
Thu Sep 26, 2019 8:09 pm
Forum: past events & exhibitions
Topic: Acorn World and ABUG meetup, Cambridge 20-22nd September 2019.
Replies: 249
Views: 11446

Re: Acorn World and ABUG meetup, Cambridge 20-22nd September 2019.

Thanks all for the warm welcome and excellent organization / program -- I had a blast.

I left with a real beeb stuffed into my backpack -- interesting times at Heathrow security -- and I will redouble my efforts to better understand the machine for purposes of accurate emulation!


Cheers
Chris
by scarybeasts
Sat Sep 07, 2019 10:30 pm
Forum: software: classic games
Topic: Stryker's Run
Replies: 9
Views: 822

Re: Stryker's Run

Sorry if the original post wasn't clear. No, I already have my own copy of it. The tape is available to download from StH but the disc isn't. So I just wanted an upload of the disc which Bill Carr has provided. Cool. I'll add it to Everygamegoing so it's available for everyone too. The same STH dis...