Search found 254 matches

by Ramtop
Fri Nov 13, 2020 10:38 am
Forum: 8-bit acorn hardware
Topic: Help - Implementing Shadow RAM in CPLD
Replies: 135
Views: 3458

Re: Help - Implementing Shadow RAM in CPLD

I'll second that. There were some bizarre random issues with early revisions of my ElkSD boards on some Electrons that had me pulling my hair out, and the root cause was the XC9536XL it uses being thrown off by a noisy clock. Running the Electron's clocks through a Schmitt trigger buffer fixed the p...
by Ramtop
Sun Nov 08, 2020 8:56 pm
Forum: for sale / freebies
Topic: Electron SD Interface & SW Ram Expansion
Replies: 58
Views: 7345

Re: Electron SD Interface & SW Ram Expansion

Hi I was wondering if it'd be possible to use an adapter pcb to convert an ElkSD64 into the Plus One version, e.g. a pcb that slots into the ElkSD64 which fits in a cartridge slot? Sadly, no. The devices are quite different and there would be numerous problems involved. One example: the ElkSD64 des...
by Ramtop
Sun Nov 08, 2020 8:45 pm
Forum: for sale / freebies
Topic: Electron SD Interface & SW Ram Expansion
Replies: 58
Views: 7345

Re: Electron SD Interface & SW Ram Expansion

If that were to happen, would it not be possible to block the Electron booting from ROM in the same way you do with other physical roms when using a plus1. Press CTRL+Break then wait about a second and hit escape? Obviously I'm not willing to test out that question given the card just arrived and I...
by Ramtop
Wed Nov 04, 2020 2:38 pm
Forum: 8-bit acorn hardware
Topic: ElkSD Plus 1 Card?
Replies: 5
Views: 216

Re: ElkSD Plus 1 Card?

the supplier only seems to be contactable via ebay messaging. I hang out here as well :D As I said via Ebay, it's a problem with the card you're using. A few of the really cheap Chinese ones don't implement SPI mode correctly, and the ElkSD uses SPI to communicate with the card. It's not an age or ...
by Ramtop
Sun Nov 01, 2020 12:15 pm
Forum: for sale / freebies
Topic: Electron SD Interface & SW Ram Expansion
Replies: 58
Views: 7345

Re: Electron SD Interface & SW Ram Expansion

Out of interest, IF a card is bricked due to a bad flash update or uploading a game into the ROM rather than RAM and getting stuck with it auto-booting. Is there any way recover from this even if it requires some extra hardware to reflash things directly? I've no idea about the hardware used in thi...
by Ramtop
Thu Oct 29, 2020 9:14 pm
Forum: the complete BBC games archive
Topic: The complete Electron games archive
Replies: 23
Views: 1517

Re: The complete Electron games archive

Oh, yes, using main memory as a buffer will certainly work. I was thinking more along the lines of people trying to load a ROM image directly into bank 12 with *SRLOAD. No way to make that happen. I wish I'd been able to implement a split ROM/RAM bank for MMFS in the 64, as is the case with the ElkS...
by Ramtop
Thu Oct 29, 2020 7:29 pm
Forum: the complete BBC games archive
Topic: The complete Electron games archive
Replies: 23
Views: 1517

Re: The complete Electron games archive

If Gary wants to use the photo there is no problem for it... Your photographic skills are certainly better than mine! :D To give a definative answer on using bank 12 for ROM images for anyone who's interested: no it's not possible. The ElkSD64 uses the 'Z' version of MMFS which copies itself from R...
by Ramtop
Tue Oct 27, 2020 1:43 pm
Forum: 8-bit acorn hardware
Topic: 65816 speed grades
Replies: 6
Views: 206

Re: 65816 speed grades

Mouser sells brand new DIP 65C816-14s:
https://www.mouser.co.uk/ProductDetail/ ... JD3DWt8%3D
by Ramtop
Wed Oct 21, 2020 8:03 pm
Forum: 8-bit acorn hardware
Topic: Hard Gold or Enig Finish for Edge Connector Fingers
Replies: 11
Views: 249

Re: Hard Gold or Enig Finish for Edge Connector Fingers

Can't comment on other fabs, but JLC strip everything but the copper/gold finish from the contacts area when you select gold fingers. I found that out by accidentally uploading the wrong gerbers for a board, where I hadn't removed the solder mask and actually had left silkscreen over the top of the ...
by Ramtop
Wed Oct 21, 2020 6:26 pm
Forum: 8-bit acorn software: other
Topic: MMFS Version 2
Replies: 368
Views: 2683

Re: SD card without the MMB file (aka MMFS2)

I don't think it's been updated at all since then. I implemented MMFS2 as an option on my original ElkSD-Plus 1 catridge since I'm not much of a fan of the beeb.mmb file approach, but it seemed to just die so I got cold feet and went back to the standard build of MMFS for rev 2 of the cartidge.
by Ramtop
Wed Oct 21, 2020 6:19 pm
Forum: 8-bit acorn hardware
Topic: Hard Gold or Enig Finish for Edge Connector Fingers
Replies: 11
Views: 249

Re: Hard Gold or Enig Finish for Edge Connector Fingers

JLC doesn't permit gold fingers without ENIG, but since they don't charge extra for it either I'm not entirely convinced they're doing anything but removing the solder mask between the contacts.
by Ramtop
Wed Oct 21, 2020 12:23 pm
Forum: 8-bit acorn hardware
Topic: Hard Gold or Enig Finish for Edge Connector Fingers
Replies: 11
Views: 249

Re: Hard Gold or Enig Finish for Edge Connector Fingers

All my production ElkSD-Plus1 cartridges use JLCPCB's ENIG finish with 'gold fingers' and I've never had any reported issues with wear on the contacts. The prototypes used HASL, and one thing I have found is that ENIG boards need to be kept *very* clean to make a good contact. Presumably becaue HASL...
by Ramtop
Thu Oct 15, 2020 9:29 pm
Forum: 8-bit acorn hardware
Topic: Beeb816 Revival
Replies: 39
Views: 1657

Re: Beeb816 Revival

Getting hold of that CPLD may be an issue, the XC95108 is mostly an 'order from China and hope you don't get a fake' job now.
by Ramtop
Mon Oct 12, 2020 2:07 pm
Forum: 8-bit acorn hardware
Topic: Beeb816 Revival
Replies: 39
Views: 1657

Re: Beeb816 Revival

Oooh, very interesting! :D
by Ramtop
Fri Oct 09, 2020 11:05 am
Forum: 8-bit acorn hardware
Topic: Acorn Electron storing system
Replies: 8
Views: 368

Re: Acorn Electron storing system

If your UEF files are games then it should not really a problem as there's a huge pre-made collection of games in SSD format on the ElkSD support site at http://ramtop-retro.uk which contains the vast majority of Electron games. An alternative is the GoSDC card interface from John Kortink, which I b...
by Ramtop
Tue Sep 15, 2020 3:59 pm
Forum: general
Topic: ARM sold to Nvidia (by Softbank)
Replies: 6
Views: 523

Re: ARM sold to Nvidia (by Softbank)

I think current ownership isn't really a factor in this case. ARM is a UK based and registered company, and does the vast bulk of its work in the UK. Should the relevant regulatory authority (the CMA in this case) choose to block the deal the legal basis for doing so would seem to be valid. My under...
by Ramtop
Tue Sep 15, 2020 12:33 pm
Forum: 8-bit acorn hardware
Topic: RetroClinic DataCentre remake
Replies: 15
Views: 544

Re: RetroClinic DataCentre.

I had search for the XC9572, which as you say is obselete, though UTSOURCE can supply used chips, which maybe a risk, as some used chips are either faulty or counterfeit. Very risky to go that route I think. Most of those chips are likely salvage parts removed from scrapped PCBs using hot air, and ...
by Ramtop
Mon Sep 14, 2020 8:46 pm
Forum: general
Topic: ARM sold to Nvidia (by Softbank)
Replies: 6
Views: 523

Re: ARM sold to Nvidia (by Softbank)

I don't see it happening, to be honest. Even discounting the very high likelihood of the UK government blocking the deal, or at least forcing onerous conditions on it, the Chinese regulators will not want to see such a critical IP provider under the control of what it sees as a hostile power. I'm st...
by Ramtop
Fri Sep 04, 2020 6:13 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

Received a WDC65C02-14 today but despite disconnecting pin 1 and pulling BE high it didn't work when plugged into the turbo board, but worked fine directly in the Elk's CPU socket. Cue much head scratching. And then I remembered... a WDC65C02 at 5v won't accept 3.3v as a logic high, and I'm driving ...
by Ramtop
Wed Sep 02, 2020 4:21 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

PCBs have been ordered, when they arrive and I can validate that I haven't horribly messed something up I will make the PCB and HDL files available and build a few boards for those who have expressed an interest. I've re-worked the design to use a CPLD with 0.8mm pitch pins rather than the previous ...
by Ramtop
Sun Aug 30, 2020 3:41 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

A little more progress to report. After much pulling of hair and bashing of desk and bodging of wires, the turbo card now runs at 4MHz using an R65C02P4. The implementation is very 'sub-optimal' at the moment. Only the lower 12K area is 4MHz and there's a significant performance penalty going from a...
by Ramtop
Sat Aug 29, 2020 8:02 am
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

I'm going to have to disappoint on both of those, I'm afraid - at least with the current design. :( To do register based speed control the CPLD would need access to enough of the address bus to do useful decoding, and at present it only has A12-A15. For the same reason sideways RAM isn't possible as...
by Ramtop
Fri Aug 28, 2020 2:29 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

I've put up a short video showing the board in action: https://www.youtube.com/watch?v=LTD66cByMWM

(sorry for the naff quality, video is not my thing)
by Ramtop
Thu Aug 27, 2020 9:25 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

I've finished the fixes to the board, which amounted to almost a redesign. The CPU is moved back a bit for clearance and I've swapped the CPLD for a smaller, cheaper and easier to solder part. I'll order the PCBs at the weekend, they usually take about 2 weeks to arrive from China. Found time to bod...
by Ramtop
Sat Aug 22, 2020 9:52 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

Thanks, guys :D Dave, your points about sockets are well made. I had a single low-profile socket in my parts bin and planned to use it on the motherboard, but turns out the pins I'm using on the bottom of the turbo card are square in shape and won't fit into a turned pin socket. Need to get some nic...
by Ramtop
Fri Aug 21, 2020 10:34 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Re: Elk turbo board

I'll do another revision, it's fairly necessary since I really like the Elk with some extra speed and will end up fitting all of mine with turbo cards, but it's handy being actually able to close the case properly :D Toying with the concept of doing two separate versions; a bug fixed version of the ...
by Ramtop
Fri Aug 21, 2020 6:41 pm
Forum: 8-bit acorn hardware
Topic: Elk turbo board
Replies: 20
Views: 1145

Elk turbo board

Hi all, About 18 months ago I got the idea of trying my hand at a minimalist turbo card for the Electron. I finished the PCB layout, wrote most of the Verilog for the CPLD, and then became distracted by other things without ever building one to see if it worked. A few weeks back I found the old file...
by Ramtop
Sat Aug 15, 2020 10:42 pm
Forum: off-topic
Topic: PC Memory Timing Strangeness
Replies: 11
Views: 651

Re: PC Memory Timing Strangeness

That's interesting. It does seem to be do quite a comprehensive set of tests and can any set ever be exhaustive? The problem with Memtest is its generic nature as it's written to run on such a wide range of hardware. A really punishing memory test would need to be aware of the specific CPU and enti...
by Ramtop
Mon Aug 03, 2020 1:33 pm
Forum: 8-bit acorn software: classic games
Topic: Electron enhanced versions?
Replies: 13
Views: 1170

Re: Electron enhanced versions?

Was also, considering one of these... https://www.ebay.co.uk/itm/143445748901 ...but if the extra RAM isn't used by anything I'm not sure whether to or not. Cheers! The ElkSD-Plus1 needs a RAM chip on it to provide workspace for the SD card software, and since 32K chips are no more expensive than 1...
by Ramtop
Thu Jul 23, 2020 3:00 pm
Forum: general
Topic: SD Card on Fire
Replies: 31
Views: 1677

Re: SD Card on Fire

Ouch, lucky escape indeed!

SD cards have little capacitors in them which can sometimes fail as a dead short, and if the host device doesn't have current limiting on the power rail then the cap basically becomes a small heating element.

Go to advanced search