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#241 |
ex. demoscener "Bigmama"
Join Date: Jun 2012
Location: Fyn / Denmark
Posts: 1,637
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Turning "off" the original version (i.e. slowing it down to ~OE speed) is implemented by disconnecting it from the local ram, IIRC.
What sort of speed advantage does the SE version offer without local ram? |
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#242 | |
Registered User
Join Date: Aug 2020
Location: UK
Posts: 14
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Quote:
I'll have to lookup how to specificity test the DMA side of the GVP. so far I've just been using the machine as normal. but I've noticed a few things, if I boot it with out the GVP and run SysInfo I got a slower speed (of around 11mhz). but running Operation Stealth from floppy disk with the GVP disconnected worked. I've also tested a few more games and had mixed experiences. with more of them crashing. This might indicate issues with the DMA (I tried changing the max transfer speeds for the partitions to see if that was the issue, and it didn't affect it in anyway). My next step will be to run running op-stealth from floppy with the drive connected. |
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#243 |
Registered User
Join Date: Aug 2020
Location: UK
Posts: 14
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Just tested it running from the floppy drive, while the HD8 is connected.
and it having booted workbench from the drive. and it seems to run fine. I'll look at trying to source a HC 68000. but it does look like running games from the hdd is the issue. |
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#244 |
Registered User
Join Date: Aug 2020
Location: UK
Posts: 14
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Tried it out with a HC cpu and it ran a little better.
but it was still reporting 12.50mhz and some games still crashed. so not sure if its the design, the DMA transfer or if I've built it wrong. |
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#245 |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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I think you build it right. the fact that a 68HC000 makes it work better makes me believe the problems are related to subtle timing issues with the DMA bus request signals.
That it works at all and that you are able to boot from the HDD means that in general things are working. I'll think it over during the weekend :-) Maybe there are some things we can try. |
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#246 |
Registered User
Join Date: Mar 2018
Location: New Ferry
Posts: 521
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I had a go of building ver 2.2 yesterday and found it really difficult. do the Cx resistors have to go on a specific way? 2 of them say 222 on but the bag they were in says 22p, will they be ok?
edit: The photo on github says it should be 222 so thats that answered. Do I need to bridge the JPx joints? Last edited by ItsTheSmell; 12 July 2023 at 20:04. |
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#247 | |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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Quote:
and yes, you should bridge the JPx (Jumpers) joints. If you find the build difficult it might be worthwhile to first build the version without fast RAM. The jumper settings (solder bridges) are shown on the bottom of the board. Then, if everything works you can add the fast RAM and associated components. Remember to change the jumpers then. |
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#248 |
Registered User
Join Date: Mar 2018
Location: New Ferry
Posts: 521
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Ok mate thanks for the info.
I have the version that allows passthrough to the zorro bus for a Supra Ram 500XP, ill build it next week if this one works. I think i need a better soldering iron; my one is from maplin and it leaves cold joints when set to maximum. |
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#249 |
Registered User
Join Date: Oct 2019
Location: UK
Posts: 29
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22p (Capacitor)
222 (Resistor). 222 is 2k2/2.2k = 2000 and 200 Ohms.(As mentioned by Mathesar) Resistors are numbered, capacitors are coloured. I would first clean the PCB with alcohol, then use the thick/cloudy flux, rather than the thin clear stuff. Don't worry too much about cloudy solder joints, as there's never going to be any kinetic movement on the smd components. The pin headers will require good soldering joints tho. ps; Remember, leaded solder and non-leaded solder require different temperatures. Which might explain your dull/cold joints. Last edited by keithamiga1200; 14 July 2023 at 14:35. Reason: Additional info |
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#250 |
Registered User
Join Date: Mar 2018
Location: New Ferry
Posts: 521
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So, I've treated myself to a fancy new AiXun T3A iron. I was planning on building the SE board but I can't find any pictures to follow. Nothing on GitHub. Anyone got a link to one?
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#251 | |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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Quote:
His board worked but it didn't solve the DMA issue with SCSI side-cars like the A590. |
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#252 |
Registered User
Join Date: Mar 2018
Location: New Ferry
Posts: 521
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In that case is there anyway i can buy the ram chips for the standard accelerator?
My SupraRam 500XP doesnt always work with some games. I have to switch it off before booting. How compatible is your accelerator? |
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#253 |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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The full accelerator is very compatible as long as there is no DMA SCSI device hanging on the side. So, as long as the full accelerator is installed, you cannot use the supraram's harddisk at all.
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#254 |
-
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 43
Posts: 9,900
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The SupraDrive 500XP doesn't do DMA, but it does need working autoconfigure.
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#255 |
Registered User
Join Date: Mar 2018
Location: New Ferry
Posts: 521
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If the accelerator works ill sell the supraram. However, i cant find anything on ebay. Help!
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#256 |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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#257 |
Mostly Harmless
Join Date: Aug 2004
Location: Northern Ireland
Posts: 1,149
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Is there anyone selling these ready built?
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#258 |
Registered User
Join Date: Feb 2020
Location: Stockholm
Posts: 4
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SE with A590
I've built the SE version (rev 3.0), to test it with my A590 (SCSI HD and 2MB RAM).
Here are my experiences: - The build was fairly easy and even with beginner soldering skills, it took just a few hours. - The card with the CPU installed fits under the metal shielding, which is nice - JP1 -> I connected the 1-2 (int. default) option. - Without the A590 the card works, even though with my MC68000P8 SysInfo4 shows it to be 11.6MHz and the performance is slower than on 7MHz with the A590 (0.60 vs 0.75 MIPS). Can be a timing issue? - I'm not sure if it's just my build or my cpu is not tolerating overclocking (the more likely), but it becames unstable after a few minutes and the system freezes. I'm trying to source a 68010 or another, higher rated 68000 to give it a test. - With the A590 plugged in however, it doesn't work. As soon as it tries to boot from the hard disk, it crashes. I guess the DMA issue is still present. Mathesar: any idea if it's possible to fix the DMA problem somehow? Some pics: SE card built: ![]() SE card with CPU installed: ![]() SysInfo with the SE card at 11.60Mhz, no A590: ![]() SysInfo without the SE card, 7MHz, with A590: ![]() Last edited by neongod; 17 January 2024 at 13:39. |
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#259 |
Registered User
Join Date: Feb 2020
Location: Stockholm
Posts: 4
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#260 |
Registered User
Join Date: Aug 2014
Location: Netherlands
Posts: 699
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Hi Neongod,
Yes, the fast ram is making the difference. With fast ram it should be a bit faster than with a standard 7MHz CPU. I have a theory why it still doesn't work with the A590. although the accelerator should properly tristate all signals related with DMA, there might still be a phase issue with the E clock. Do you have access to a scope? |
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