Search found 381 matches

by philpem
Tue Jul 14, 2020 3:39 am
Forum: 32-bit acorn hardware
Topic: (Repair) A4000 motherboard resurrection
Replies: 13
Views: 574

Re: (Repair) A4000 motherboard resurrection

Seems to depend on which formatter you use. https://stardot.org.uk/forums/viewtopic.php?p=250834#p250834 504MB if you format using the new !hform on a RPi, or 499MB if using !hform on the A4000. Sounds like I'll need to repartition and reformat at some point then, I picked 504MB and used the ICS ID...
by philpem
Mon Jul 13, 2020 8:13 pm
Forum: 32-bit acorn software: other
Topic: Setting up AppFS on an Econet (HOWTO)
Replies: 1
Views: 35

Setting up AppFS on an Econet (HOWTO)

Angelsoft AppFS has been downloadable from Chris's Acorns for a while, but I don't think I've ever seen a scan of the manual. I decided to have a play with it this evening, and it turns out to be quite easy to set up. First the big gotcha: AppFS works by transferring data on the disc sector level. I...
by philpem
Mon Jul 13, 2020 7:52 pm
Forum: 32-bit acorn software: other
Topic: The Hidden Fifth Column: Integrating Wizzo with RISC OS 3.11
Replies: 5
Views: 101

Re: The Hidden Fifth Column: Integrating Wizzo with RISC OS 3.11

Great work/investigations! This sounds like a very simple way of adding new modules to RISC OS ROMs without all the pain of rolling the whole RISC OS back together. I’m assuming this works...it certainly sounds like it should? (I don’t think you actually say whether it does though?) Oh it definitel...
by philpem
Mon Jul 13, 2020 7:48 pm
Forum: 32-bit acorn hardware
Topic: A3020 red screen
Replies: 17
Views: 195

Re: A3020 red screen

That board needs a very good clean to get all the rust stains off, or you're not going to get anywhere with it... Rust is electrically conductive.

The metal track around the outside edge is fine (you probably won't get the rust off of that) but the RAM tracks need to be clean.
by philpem
Mon Jul 13, 2020 7:24 pm
Forum: 32-bit acorn hardware
Topic: A3020 red screen
Replies: 17
Views: 195

Re: A3020 red screen

I'd want to see the underside of the board... If the battery corrosion has reached the memory I fear it may be rather bad under there.. It does really all need neutralising with distilled vinegar before giving it a good wash with distilled water as mentioned above. I expect the batter goo has eaten...
by philpem
Mon Jul 13, 2020 4:48 pm
Forum: 32-bit acorn hardware
Topic: Acorn "POST box" display adaptor (0086,804)
Replies: 117
Views: 5589

Re: Acorn "POST box" display adaptor (0086,804)

I edited these two lines in the code to suit the 8MHz clock: https://github.com/hoglet67/acorn_postbox/blob/master/top.v#L63 https://github.com/hoglet67/acorn_postbox/blob/master/top.v#L94 I assume the first one is for the comms with the POST header, and the second is the LCD write delay. Exactly r...
by philpem
Mon Jul 13, 2020 3:49 pm
Forum: 32-bit acorn software: other
Topic: The Hidden Fifth Column: Integrating Wizzo with RISC OS 3.11
Replies: 5
Views: 101

The Hidden Fifth Column: Integrating Wizzo with RISC OS 3.11

I've been having a play around with some of the RISC OS ROM modding tools dotted around Stardot, with varying degrees of success. I think I've found a "better" way which doesn't involve huge amounts of ROM hackery. Many of you will be familiar with the 5th Column ROM socket. As it happens, the Podul...
by philpem
Mon Jul 13, 2020 2:55 pm
Forum: 32-bit acorn hardware
Topic: Acorn "POST box" display adaptor (0086,804)
Replies: 117
Views: 5589

Re: Acorn "POST box" display adaptor (0086,804)

I found why my POST adapter was outputting garbage on my RISC-PC 700 vs RISC-PC 600. The RISC-PC 700 is announcing the POST message on the adapter then ignoring POST and booting. The RISC-PC 600 runs POST as expected and loops once it reaches the end. If TESTACK is open circuit, you'll get this beh...
by philpem
Mon Jul 13, 2020 1:35 pm
Forum: 32-bit acorn hardware
Topic: Acorn "POST box" display adaptor (0086,804)
Replies: 117
Views: 5589

Re: Acorn "POST box" display adaptor (0086,804)

Some success, swapping the resistors for 470R, with the same 1nF capacitor, gave the following: IMG_20200713_1318523.jpg Subsequent screens followed; some had title and data, others were just the title, with a blank second row. I'm not sure if that's as exepcted, but there's a lot of battery damage...
by philpem
Mon Jul 13, 2020 1:18 pm
Forum: 32-bit acorn hardware
Topic: Acorn "POST box" display adaptor (0086,804)
Replies: 117
Views: 5589

Re: Acorn "POST box" display adaptor (0086,804)

I know I won't find one in the house (without disassembling my System 1!), but I may well buy one in if swapping component values doesn't get the ball rolling. The soldering iron's just been switched on... They do make the job a lot easier! The circuits I used were like this: https://electronics.st...
by philpem
Mon Jul 13, 2020 12:03 pm
Forum: 32-bit acorn hardware
Topic: Acorn "POST box" display adaptor (0086,804)
Replies: 117
Views: 5589

Re: Acorn "POST box" display adaptor (0086,804)

Good call: I've got 10K and 1nF, as in your PDF schematic, but a poke with my scope shows it's not oscillating. Jury-rigging an external 8MHz clock into pins 6 and 7 of the 74ls04 socket got some (nonsensical) characters onscreen, so I'll see about getting the soldering iron out and investigating f...
by philpem
Mon Jul 13, 2020 11:46 am
Forum: 32-bit acorn hardware
Topic: Acorn AKA20 We32206 Floating Point Co-Processor
Replies: 27
Views: 1057

Re: Acorn AKA20 We32206 Floating Point Co-Processor

dp11 wrote:
Thu Feb 27, 2020 12:48 pm
Yes WSS sold it. I have the builds and source code in the loft. I'll dig it out if you are interested.
I'd love to have a play with FPEPC. Next time you're up in the loft, could you please grab them and upload them to the forum?

Cheers
Phil
by philpem
Mon Jul 13, 2020 3:09 am
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

Quick update -- While working on 5th Column ROMs I think I've stumbled upon a minor breakthrough. The same rules apply to the RISC OS ROM as apply to 32-bit-wide 5th Column ROMs. The Modules in the ROM are executed in-place. That means they need to start and end on a 4-byte (word) boundary. If a Mod...
by philpem
Mon Jul 13, 2020 2:28 am
Forum: 32-bit acorn software: other
Topic: Roll your own RISC OS 3.1x
Replies: 7
Views: 2144

Re: Roll your own RISC OS 3.1x

Another bug. The padding logic is completely wrong (specifically, it's backwards). When fixed, it creates an empty Module which causes an address exception crash on boot. The module is full of NOPs, which are out-of-range addresses in the context of a module header. The workaround is to pad any modu...
by philpem
Sun Jul 12, 2020 11:05 pm
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

In my case it was failing to boot on Arculator too, even after I'd patched it to work with 4MB ROMs. It displayed the RISC OS 3 banner, then hung on a blank grey screen with a blue cursor. I must have got the checksum algorithm right, because my patched ROMs matched the original RO3.11 and RO3.19 o...
by philpem
Sun Jul 12, 2020 7:55 pm
Forum: 32-bit acorn hardware
Topic: A3020 red screen
Replies: 17
Views: 195

Re: A3020 red screen

The first thing I'd do with a board like that is give it a good clean -- first with water and an ESD-safe brush, then again with 99% isopropyl. The rust spots and corrosion near the RAM could well be the cause of the control line failure. Also check the RAM size jumpers are set correctly -- and aren...
by philpem
Sun Jul 12, 2020 7:12 pm
Forum: 32-bit acorn hardware
Topic: A3020 red screen
Replies: 17
Views: 195

Re: A3020 red screen

hi, sorry. flashes are: SSSS SSSS SSSS SSLS SSSS SSSL SLSS SSSL Going from here: https://www.retro-kit.co.uk/page.cfm/content/Common-RISC-OS-POST-failure-errors/ That maps to: RAM control line failure CMOS RAM checksum error And two status flags which aren't errors: PC-style IO world detected (this...
by philpem
Sun Jul 12, 2020 4:55 pm
Forum: 32-bit acorn software: other
Topic: Roll your own RISC OS 3.1x
Replies: 7
Views: 2144

Re: Roll your own RISC OS 3.1x

One more for the road. Here's my patched version of Build, with the following changes: Fix the Stray-0x0A bug when adding the Module Trailer (which broke binary reproducibility) If no filler is required, indicate that as a comment instead of throwing an error. If the ROM address has gone past the sp...
by philpem
Sun Jul 12, 2020 4:27 pm
Forum: 32-bit acorn software: other
Topic: Roll your own RISC OS 3.1x
Replies: 7
Views: 2144

Re: Roll your own RISC OS 3.1x

Holy necrothreads, Batman! I've been poking at the "RISC OS 3.20" project which seems to have similar goals to this. To that end, I've put together some tools to pad the ROM up to 4MB and fix the checksums and ROM size in the header: https://github.com/philpem/riscos-romtools/ I'm getting a couple o...
by philpem
Sun Jul 12, 2020 2:16 pm
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

I've updated the build code (Build320-101.zip) in the OP with the checksum and CRC calculations. Hopefully you'll now get valid ROM's on physical Arcs - unfortunately it's not something I can test yet. I believe the reason you're struggling to get the CRC to match what the current RISC OS CRC code ...
by philpem
Sun Jul 12, 2020 12:43 pm
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

I've gone back to basics on this one. Take the known-good RISC OS 3.11 ROM image from 4corn (which works in a 27C800) Pad it out to 4MB Correct the checksums and ROM Size word Stripe the image into "high" and "low" ROMs Program them into EPROMs and install them in the A4000 Boot the A4000 Dump the 4...
by philpem
Sun Jul 12, 2020 12:32 pm
Forum: 32-bit acorn hardware
Topic: Mounting a floppy drive in an A310
Replies: 15
Views: 317

Re: Mounting a floppy drive in an A310

To be fair the £35 is probably worth it for a plug that's more or less guaranteed to work perfectly every time without knackering the PLCC socket...
by philpem
Sun Jul 12, 2020 12:08 pm
Forum: 32-bit acorn hardware
Topic: RISCPC Power Supply Refurbish
Replies: 30
Views: 508

Re: RISCPC Power Supply Refurbish

I'll also provide kits of parts for anyone wanting to refurbish their own supply. Reply here if you're interested and I'll order parts accordingly. I'll take two -- my daily-driver RISC PC has the higher rated PSU in there (it came with a second-slice upgrade). I think the other is sporting a 70-mu...
by philpem
Sun Jul 12, 2020 11:28 am
Forum: 32-bit acorn hardware
Topic: RISC PC motherboard refurbish
Replies: 13
Views: 301

Re: RISC PC motherboard refurbish

I recently decided to refurbish my RISC PC motherboard because although it worked, I could see some electrolyte leaking from surface mount electrolytics, which isn't a good sign! Although there was visible leakage it seemed to have 'dried' without damaging the PCB. There was leakage under most if n...
by philpem
Sun Jul 12, 2020 11:21 am
Forum: 32-bit acorn hardware
Topic: R260 - missing CPU card?
Replies: 29
Views: 951

Re: R260 - missing CPU card?

IanJeffray wrote:
Sat Jul 11, 2020 10:46 pm
£1,336.96. Holy shizz. Someone far richer than I. Wow.
Only four pence short of eliteness...

(I'll see myself out)
by philpem
Sun Jul 12, 2020 11:18 am
Forum: 32-bit acorn hardware
Topic: Repair thread: A310
Replies: 10
Views: 274

Re: Repair thread: A310

It looks like there is a copy of EcoSCSI on the hard disk.. I'd suggest taking a copy of that in case it's different to the one here. It should be fairly easy to make that disk bootable. Create an Obey file called !Boot on the floppy (start !Edit, middle click, Create -> Obey -- save as !Boot, drag ...
by philpem
Fri Jul 10, 2020 8:54 am
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

[*]Disabling the ROM checksum temporarily (always return zero) to get the thing to boot. I believe the boot process will continue eventually, after spending ages on a red screen flashing out the error code with the floppy light. That was my experience when running RO 3.20 on an A3000. Interesting -...
by philpem
Wed Jul 08, 2020 4:40 pm
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

Cheers for the info, Phlamethrower! I found the older ROM builder tool, Bigsplit2: https://gitlab.riscosopen.org/RiscOS/Utilities/Release/bigsplit2 This is a lot smaller than Romlinker and includes a separate CRC verification tool. If the CRC is correct, you'll see "CRC[n]=0x0000" for all four CRC p...
by philpem
Wed Jul 08, 2020 3:06 am
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

I've taken a look at the checksum and some of the associated code. There are a couple of things which will need patching for a 4MB ROM: The checksum (obviously) The ROM Size in the ROM Header The ROM header is described in the RO3.60 source code here: https://gitlab.riscosopen.org/RiscOS/Sources/Ker...
by philpem
Tue Jul 07, 2020 8:37 pm
Forum: 32-bit acorn hardware
Topic: RISC OS 3.20 ROM's?
Replies: 144
Views: 13613

Re: RISC OS 3.20 ROM's?

Is it possible to pare this back, a la the "Roll Your Own RO3.1x" thread (https://stardot.org.uk/forums/viewtopic.php?t=14164)? Ideally I'd like to build 3.11 (or 3.19) with Wizzo IDEFS in ROM, with as few changes to the original ROM as possible. Although I appreciate it'll be a 4MB ROM. Meanwhile I...

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