Search found 611 matches

by KenLowe
Wed Jun 19, 2019 7:41 pm
Forum: hardware
Topic: Model B ROM Board
Replies: 10
Views: 439

Re: Model B ROM Board

That one wire is enough. From the looks of things it goes to S21 (south-west), where it controls the gate on IC20, part of the mainboard's ROM selection circuitry. IC76 will be storing and latching the lower two bits of every write to the /ROMSEL address, as it normally does, but with the modificat...
by KenLowe
Wed Jun 19, 2019 3:00 pm
Forum: hardware
Topic: Model B ROM Board
Replies: 10
Views: 439

Re: Model B ROM Board

The 6502 processor seems to be missing altogether, but I guess it's hidden under the ribbon cable? Difficult to see from the photo. Assuming the 6502 is there somewhere, then it looks like the board is picking up and buffering address and data lines from the 6502. The larger IC on the board looks to...
by KenLowe
Fri Jun 14, 2019 1:44 pm
Forum: for sale / freebies
Topic: Sold Out: New ROM / RAM Expansion Board for BBC B
Replies: 66
Views: 2701

Re: Sold Out: New ROM / RAM Expansion Board for BBC B

I have just posted a new board on ebay, and notice that ebay are offering 10% off everything (valid from 12:00 PM today, Friday 14 June 2019 to 11:59Pm, Saturday 15 June 2019), so my £80 board which includes postage will come in at £72. That's just marginally more expensive than I was selling them o...
by KenLowe
Tue Jun 11, 2019 3:15 pm
Forum: hardware
Topic: 1770 wire links
Replies: 12
Views: 423

Re: 1770 wire links

marcusjambler wrote:
Tue Jun 11, 2019 9:25 am
Just trying to source the correct part
Something like this for 5.08mm spacing:

https://uk.rs-online.com/web/p/jumpers-shunts/0434728/

or this if you want 2.54mm spacing:

https://uk.rs-online.com/web/p/jumpers-shunts/1586169/
by KenLowe
Thu Jun 06, 2019 4:49 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 792

Re: BBC Master 128 schematic in KiCAD

simoni wrote:
Thu Jun 06, 2019 4:44 pm
The RTC part number has been updated and the revised version is now on github.
If I was going to be picky, the MC146818P doesn't have a MOT & nSYNC on pins 1 & 16. These signals are still shown on the part.
by KenLowe
Thu Jun 06, 2019 12:48 pm
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 792

Re: BBC Master 128 schematic in KiCAD

1024MAK wrote:
Thu Jun 06, 2019 12:02 pm
Often the A suffix indicates improvements have been made. So the MC146818A would be an improvement on the MC146818.
Mark
Indeed, but frustratingly not *quite* backwardly compatible, since you've got to do something with pins 1 & 16 on the later version to make it work as per the original!
by KenLowe
Thu Jun 06, 2019 11:15 am
Forum: hardware
Topic: BBC Master 128 schematic in KiCAD
Replies: 17
Views: 792

Re: BBC Master 128 schematic in KiCAD

Hi Simon, I was having a look at the schematic for the RTC in the Masater, and note that it's almost identical to the layout for the RTC in the IntegraB. The main difference is that the IntegraB uses a CDP6818E in place of the MC146818A that you have referenced in the schematic. I've been looking at...
by KenLowe
Wed May 29, 2019 8:56 pm
Forum: software: other
Topic: Fixed: Enhanced Exile + TurboMMC compatibility? (patched Exile)
Replies: 56
Views: 4655

Re: Fixed: Enhanced Exile + TurboMMC compatibility? (patched Exile)

I'm a recent returnee to the world of the BBC Micro and had already bought and installed a GoSDC before realising the amazing work that this thread contains. I'm planning to build an SD card reader and burn a ROM as fast as the bits can arrive in the post. I've been failing to run the STH Exile fro...
by KenLowe
Tue May 28, 2019 8:17 pm
Forum: software: classic games
Topic: BBC B Elite versions
Replies: 26
Views: 1097

Re: BBC B Elite versions

I also thought that might be the case, but I had an EEPROM (28C256) and Flash (29C256) in my board when I was doing this testing, and they passed without any problem.

...but just thinking about it, I had these modules write protected, so that's why they will have worked.
by KenLowe
Tue May 28, 2019 7:25 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3874

Re: New ROM / RAM Expansion Board for BBC B

So, myquestion is: when you enable 4/5, 6/7 and C/D you get Lancelot with graphics? if so, my board works in different mode, otherwise, what i thougt was an issue is the normal mode Yes I get graphics when all three 32k RAM modules (banks 4, 5, 6, 7, C & D) are write enabled. Edit: ...but adding a ...
by KenLowe
Tue May 28, 2019 6:39 pm
Forum: software: classic games
Topic: BBC B Elite versions
Replies: 26
Views: 1097

Re: BBC B Elite versions

So, here's the code that's checking for SWR. Addresses &7400..&740F for banks 0..F are all initially set to 0. They are set to &FF if SWR is detected. Empty banks on the IntegraB board are being detected as SWR, and the associated address is being set to &FF. Empty banks on the mainboard are correct...
by KenLowe
Tue May 28, 2019 6:09 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3874

Re: New ROM / RAM Expansion Board for BBC B

Can you please explain exactly what configuration doesn't work. I have 32k RAM in banks 4/5, 6/7 and C/D and tried various combinations, but can't get it to fail: If I write protect C/D and enable 4/5 & 6/7 Lancelot runs in graphics mode If I write protect 4/5 and enable 6/7 & C/D Lancelot runs in g...
by KenLowe
Tue May 28, 2019 2:49 pm
Forum: software: classic games
Topic: BBC B Elite versions
Replies: 26
Views: 1097

Re: BBC B Elite versions

Systems can falsely detect RAM if stray capacitance causes the voltage levels on the data bus to be retained between a write and an immediate read (or sometimes for a slightly longer period) if there is no selected device to drive the data bus. The software will then think it has detected RAM, as t...
by KenLowe
Tue May 28, 2019 12:28 pm
Forum: software: classic games
Topic: BBC B Elite versions
Replies: 26
Views: 1097

Re: BBC B Elite versions

Yes. It's definitely incorrectly identifying an empty bank as SWR. I did start to look into why it was happening, but got a bit confused by the DEF FN code that was being used for this. I'll maybe work on this a bit more tonight. On another note, I've solved my hanging issue too. Press f0 to start; ...
by KenLowe
Mon May 27, 2019 10:46 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3874

Re: New ROM / RAM Expansion Board for BBC B

Glad you got it working. No more pressure from me to have your board replaced :)
by KenLowe
Mon May 27, 2019 9:40 pm
Forum: software: classic games
Topic: BBC B Elite versions
Replies: 26
Views: 1097

Re: BBC B Elite versions

The 2nd copro version is working on my beeb thats pretty much the same set-up as yours. (Integra B,speech,vnula,RC 1770,pizero) The original and SWRAM versions hang as you've described. Just holler if you want me try stuff out. Marcus Ok. So, I've made a little bit of progress. On the SWRAM version...
by KenLowe
Mon May 27, 2019 8:26 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3874

Re: New ROM / RAM Expansion Board for BBC B

What is PAGE value on your system (>PRINT ~PAGE)? And what file system are you using?

Try to *UNPLUG all unnecessary ROMS to see if that makes any difference.
by KenLowe
Mon May 27, 2019 7:01 pm
Forum: hardware
Topic: New ROM / RAM Expansion Board for BBC B
Replies: 93
Views: 3874

Re: New ROM / RAM Expansion Board for BBC B

Sounds like you've still got some issues with your board. Firstly, can you try installing some ROM images into RAM banks 4, 5, 6 & 7 using the *EELOAD utility. This utility does a verification check of what's been installed in the RAM banks. Secondly, what happens if you switch to a shadow mode (eg ...
by KenLowe
Mon May 27, 2019 3:41 pm
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1092

Re: Page ROM/RAM

The results of this scan are stored in &2A1->&2B0. This will hold the ROM type (eg &82), or 0 if no ROM (or duplicate) is detected. So tools like *ROMS could use this to skip printing of the duplicates. (That's how my RAM Manager I wrote BITD worked, anyway). Out of interest, what does the OS do to...
by KenLowe
Mon May 27, 2019 3:34 pm
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1092

Re: Page ROM/RAM

My plan of action (given the above): 1) isolate IC20 from IC76 by removing S20 & S22 completely. This will bypass the ROM select latch. 2) have a fly lead to the middle pins of S20 & S22 so I can feed a ROM select value to IC20 from my PCB. 3) have a fly lead going to /ROMSEL so I can detect when t...
by KenLowe
Mon May 27, 2019 12:56 pm
Forum: hardware
Topic: Page ROM/RAM
Replies: 28
Views: 1092

Re: Page ROM/RAM

I don't think your truth table is quite correct. ROM15 is IC101 and is selected by Y3 going low when D0/QA and D1/QB are both set high. So, ROM15 would be selected when the databus is 15, 11, 7 or 3 (since we're ignoring the upper 2 bits D2/QC & D3/QD).
by KenLowe
Mon May 27, 2019 12:35 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

Hi Ian, I've had problems in the past where the ATF22V10C just wouldn't program at all on either the G540 or the TL866. However, the latest TL866 software seems to have addressed the issue for the TL866II-Plus. It could still be a programming issue, but the fact I can get the PLD to work correctly b...
by KenLowe
Mon May 27, 2019 12:13 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

Thanks for doing that test. Unfortunately I don't have a signal generator to replicate the test you've done, but just been browsing ebay and got a cheap one on order from China. I'm still struggling to understand why I'm seeing this behaviour with the beeb clock signal, so hopefully the signal gener...
by KenLowe
Mon May 27, 2019 6:34 am
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

I just tried it & it works as expected. Here is my build files & JED test.rar Out of interest, did you test with a 2MHz clock, and did it look anything like mine? I ask, because I've also noticed that if I clean up the clock signal (via an external inverter) before it goes into the PLD, it all seem...
by KenLowe
Sun May 26, 2019 5:33 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

I haven't studied the datasheets in huge detail, but did check that Vil & Vih were the same for both.
by KenLowe
Sun May 26, 2019 5:13 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

I just tried it & it works as expected. Here is my build files & JED test.rar I've just tried your file, and PIN14 output is still stuck low. PIN17 is pulsing as expected. I suspect my issues is to do with the slew of my clock signal, specifically when it gets inverted. By using the internal feedba...
by KenLowe
Sun May 26, 2019 5:02 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

And here's another odd thing. This fails: /* INPUTS */ PIN 13 = Phi1; /* OUTPUTS */ PIN 14 = !zPhi1; PIN 17 = !nFBackOut; /* LOGIC */ nFBackOut = Phi1; zPhi1 = !Phi1; ...but this works: /* INPUTS */ PIN 13 = Phi1; /* OUTPUTS */ PIN 14 = !zPhi1; PIN 17 = !nFBackOut; /* LOGIC */ nFBackOut = Phi1; zPhi...
by KenLowe
Sun May 26, 2019 4:16 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

cmorley wrote:
Sun May 26, 2019 4:12 pm
Try swapping the pins in case the IC is damaged?
Yeah. tried that as well. The issue follows the pin assignment. Also tried various ICs, but they're all the same. :-k :-k :-k

Oh. and thank's trying to help me here. It's really got me confused.
by KenLowe
Sun May 26, 2019 3:29 pm
Forum: off-topic
Topic: ATF22V10C vs GAL22V10D
Replies: 16
Views: 400

Re: ATF22V10C vs GAL22V10D

Yes. I'm using WinCUPL, then using the compiled .jed file in both my ATF22V10C & GAL22V10D. To be honest, I'm not sure how to go about selecting the correct mode. I assumed WinCUPL did this automatically, based on the equations. Here's a copy of the various files. Is there anything there that looks ...