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by jms2
Wed Nov 20, 2019 6:37 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 103
Views: 6015

Re: MAME: Click (and other large ROMs)

Its 15us (well, I make it 16us actually, but maybe there are some delays or something which make it 15). The divisions that take place are as shown below:
Capture.JPG
by jms2
Tue Nov 19, 2019 11:19 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 103
Views: 6015

Re: MAME: Click (and other large ROMs)

To verify the length of the IRQ pulse will have to wait until tomorrow, but I can confirm it is simply done by dividing the 16mhz clock in ic4 and ic6. The reason why you have to stop the clock is this: during host accesses to FRED an IRQ is generated by dividing the 16mhz clock. The same dividers a...
by jms2
Mon Nov 18, 2019 10:08 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 103
Views: 6015

Re: MAME: Click (and other large ROMs)

Just thought - are you stopping the second processor clock during host accesses? You should be! If you don't stop the clock, I can see how you might get more than one IRQ pulse.
by jms2
Mon Nov 18, 2019 10:01 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 103
Views: 6015

Re: MAME: Click (and other large ROMs)

If I reduce the time it misses bytes and increasing the time duplicates bytes, can't find a definitive time. Hmm, not sure. The following is the code snippet used to send a byte via &FCE5: .SendByteViaFCE5 LDA ($00),Y \ Load this byte INC $00 \ Inc LSB BNE SkipMSB \ Skip incrementing MSB unless nee...
by jms2
Mon Nov 18, 2019 3:18 pm
Forum: emulators
Topic: MAME: Click (and other large ROMs)
Replies: 103
Views: 6015

Re: MAME: Click (and other large ROMs)

Hi there, I just happened to click on this thread for the first time in a long while (I'm not a MAME user) and it dropped me close to your first query about E2P, which was in 2018! Sorry, I would have responded if I had known it was there. As you have seen, John Wike is now frequenting these forums ...
by jms2
Mon Nov 18, 2019 8:43 am
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Thanks for clearing that one up - it's obvious now you point it out. There are a few areas in the code where I didn't understand what's going on and I have put a comment to that effect: - There are some NOPs in "SendCharTo2P" - are these to introduce a delay? - Also at the end of "TransferHostto2P" ...
by jms2
Sat Nov 16, 2019 11:03 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Try this John. Works on my setup.

I left in the "only check slots 0-3" change, because the E2P can only ever occupy those slots.
v31.zip
(33.13 KiB) Downloaded 2 times
by jms2
Sat Nov 16, 2019 7:39 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Hello John I can't remember why I took that bit out... in fact I couldn't remember what was there! I removed it early on when I had ram access timing issues, and I think I forgot to put it back. One other thing I definitely changed was to only check slots 0-3 for ram, the original version checked 0-...
by jms2
Sat Nov 16, 2019 2:32 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

How about storing 4x rom images in the spare 64k, and have one selectable at any given time as being visible to the host machine?

If the ram could be battery backed up the images wouldn’t need to be loaded every time.

Oh one other idea I had was to put the E2PCODE rom on the board somehow.
by jms2
Sat Nov 16, 2019 2:25 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

I had a similar idea, but not the skills to implement it!

It does seem a waste to have that memory available but not use it. Also the board occupies two slots but only uses one.
by jms2
Tue Nov 12, 2019 9:37 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

It’s unwise to speculate on how many products were produced or which still exist on the very small number of samples available via a forum. I agree, but actually I was speculating unwisely based mainly on some completely different factors - (a) my guess of how popular these things might have been, ...
by jms2
Tue Nov 12, 2019 9:21 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

iwasjafa wrote:
Tue Nov 12, 2019 5:41 pm
Hi John,

Do you have any boards available yet?
I thought I had PM'd you about this John, but I have just realised that in fact I hadn't. Sorry about that! I have a small number of "Mark 2" boards on the way so I'll PM you about it now...
by jms2
Tue Nov 12, 2019 9:06 pm
Forum: software: other
Topic: 6502 assembler for Windows/Linux
Replies: 8
Views: 268

Re: 6502 assembler for Windows/Linux

I'm using BeebAsm John. One of the great attractions of this is that you can use BeebDis to disassemble existing code straight into the format recognised by BeebAsm, then comment the code and rebuild it. This is the technique I used to reverse engineer your E2P code.
by jms2
Tue Nov 12, 2019 4:39 pm
Forum: archive requests
Topic: PMS 64K Non-Volatile Ram Module
Replies: 9
Views: 238

Re: PMS 64K Non-Volatile Ram Module

That sticker on the 64k ram module says "*ROSON", which suggests to me that the Advanced Ram Operating System was intended for the 64k module. However it would make sense if it also worked with the Z-modules as well (given that they were bigger, and match the bigger sizes listed in the rom). It's in...
by jms2
Sun Nov 10, 2019 11:57 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2794
Views: 273923

Re: Worth Taking a Look At

Thanks Nigel, I had not seen that interface before. Having the cable coming out of the bottom is unusual but neat.
by jms2
Sun Nov 10, 2019 7:55 pm
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2794
Views: 273923

Re: Worth Taking a Look At

Anyone know what this Elk expansion unit is? I'm not thinking of buying it, just intrigued.

https://www.ebay.co.uk/itm/Vintage-Retr ... Swa0ddmbLH
by jms2
Sat Nov 09, 2019 11:28 pm
Forum: archive requests
Topic: PMS 64K Non-Volatile Ram Module
Replies: 9
Views: 238

Re: PMS 64K Non-Volatile Ram Module

Quite. I assume the price is based on rarity (and optimism!)
by jms2
Sat Nov 09, 2019 10:58 pm
Forum: archive requests
Topic: PMS 64K Non-Volatile Ram Module
Replies: 9
Views: 238

Re: PMS 64K Non-Volatile Ram Module

There is one currently for sale on Ebay actually.
by jms2
Wed Nov 06, 2019 1:30 am
Forum: hardware
Topic: Electron internal mode 7 rom needed
Replies: 8
Views: 355

Re: Electron internal mode 7 rom needed

There's a copy of it on Derek Walker's page http://www.bygonebytes.co.uk/electron.html, along with some great historical information that you may have also been looking for!
by jms2
Mon Nov 04, 2019 11:22 pm
Forum: hardware
Topic: Master sideway ram question
Replies: 7
Views: 370

Re: Master sideway ram question

I presume you mean two rom images, on disk?

If so, you can only load them into banks 4, 5, 6 or 7 on a master. They would fill two slots, leaving two left. You can't use slot 0 because that is assigned to one of the physical cartridge slots.

Hope that helps!
by jms2
Sun Nov 03, 2019 6:59 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

I'm not sure about the 4MHz problem. I would have to look at the circuit in detail to see what might be a problem and I am out today. However the 16MHz and phi0 circuits are where I would start. Don't worry about the 4MHz question - now that it's easily possible to use a Raspberry Pi as a second pr...
by jms2
Sun Nov 03, 2019 7:27 am
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

I had thought the same thing, but actually the NMI is necessary according to my understanding of the software. Every time an NMI occurs, the system refreshes some of the DRAM but then, crucially, checks for a command from the host in the relevant register. My version doesn't do the refresh, but it d...
by jms2
Sat Nov 02, 2019 11:21 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Good news - just tested the latest version with the issue 6 machine, with the MRB switched on. Seems to work fine. So I dont know what caused the previous problem. This makes me very much inclined to get a handful of new boards made up.
by jms2
Sat Nov 02, 2019 10:16 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

I'm tempted to get some "mark 2" boards made - the cost is surprisingly low. There's one other issue I want to check out as well before I send anyone a board - I have two Electrons, and whilst the E2P works perfectly with one, it didn't used to be happy with the other. The good one is an Issue 4 wit...
by jms2
Sat Nov 02, 2019 7:20 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Some photos for John's benefit. E2P board.JPG The board (this is the one which needs the bodge wires on the other side) Running.JPG This shows it running your original software. P1130876.JPG The new in-rom manual (there are many pages of course, I arranged it to automatically go into paged mode so i...
by jms2
Sat Nov 02, 2019 4:49 pm
Forum: hardware
Topic: Looking for inspiration - debugging E2P
Replies: 91
Views: 2984

Re: Looking for inspiration - debugging E2P

Mea culpa! I have just joined this forum and am impressed by the effort you have put in to correct a bug in my original code! It is many years since I stopped doing Jafa Systems and I must confess that I have completely forgotten everything! I have only recently started playing with an Electron aga...
by jms2
Tue Oct 29, 2019 8:00 pm
Forum: software: other
Topic: Game with Demo for Showing Off?
Replies: 9
Views: 414

Re: Game with Demo for Showing Off?

Galaforce is good. Again, nice music.
by jms2
Sat Oct 26, 2019 8:46 am
Forum: hardware
Topic: Loading a ROM into SW Ram - basics
Replies: 39
Views: 885

Re: Loading a ROM into SW Ram - basics

The problem breaks down into two stages: 1. Getting the file onto a disc image (eg, a .ssd file) that you can load into your Gotek. 2. Loading the file from the disc image into sideways ram. For step 1, you need a disc image editor which will allow you to create a new blank disc image and copy the f...
by jms2
Fri Oct 25, 2019 10:05 pm
Forum: archive submissions
Topic: Asteroids - Computer Concepts 1982
Replies: 7
Views: 332

Re: Asteroids - Computer Concepts 1982

Nice one!

Also, that's the same Jeremy Smith who went on to write Thrust and Exile.
by jms2
Thu Oct 24, 2019 11:27 am
Forum: introduce yourself
Topic: Hello from Glasgow
Replies: 16
Views: 634

Re: Hello from Glasgow

I downloaded that one, but I think it is for the BBC. In their adverts PMS said that they had commissioned a specially-written version. The issue is not compatibility with the E2P, it's compatibility with the Electron (and its lack of Mode 7). Obviously on the Elk all the screen displays are in mode...