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Old 05-11-2009, 03:54 AM   #1
benb123
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Default CSA Mega Midget Racer

Hi All,

I have recently obtained (at a cost of 450 USD in total with postage and VAT) a CSA Mega Midget Racer that I plan, in 6 months time when I get back to Perth, to insert into the welcoming 68000 socket of an A1000. The card has:

- 68030RC50B CPU installed (36.0Mhz crystal but 50Mhz CPU)
- 68882RC50A FPU (using the separate 50.0Mhz crystal)
- 8Mb 80ns 16 x 1Mb x 4 bit Daughterboard.
- 512Kb SRAM

I have a few questions which all relate to the midget racer though they possibly span different threads also. All apologies if this is the case.

Q1)
You probably already know my first question. Has anyone clocked this card successfully beyond the 38Mhz they mention in the manual? Mine is 36Mhz which is probably close enough to the 38Mhz crystal (but it still would be nice to have the 2Mhz). Instant geek titillation. :-D

Q2)
I figure that 60ns DRAMs could be 16.6 Mhz read time vs the current 12.5Mhz read time or up to 33% faster but I don't know how much difference this would really make. Anyone have experience with this?

Q3)
As I said, I have an A1000 and would love to somehow copy the 3.1 ROM image into that static ram (as there is 512Kb). Anyone done this thru whatever means. I purchased Amiga Forever Premium and managed to use the TwinKick on a floppy to boot up the emulator with 3.1 on a virtual A1000. It is very cool but I am still trying to figure how I could use this with the mega midget racer most efficiently.

If the utilities provided are clever enough perhaps they could locate the "ROM" regardless of whether it is located in ROM or RAM (isn't there a vector for this somewhere in the memory map? Too long ago...).

Q4)
I have an ADIDE in an A500 (also never having seen it as yet) that also uses the 68000 socket. I plan on putting this one in first followed by the mega midget racer as I believe it should work. Anyone experienced this setup?

Ok. Well I will stop there. All comments appreciated. :-D

-- Ben

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Old 05-11-2009, 04:08 AM   #2
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Default Re: CSA Mega Midget Racer

http://amiga.resource.cx/exp/megamidget

Quote:
optional 512 kB SRAM

* much faster (and more expensive) than DRAM
* four sockets for 128 kB SRAMs
* can be used for Kickstart remapping
check the software utility disk on that page.
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Old 05-11-2009, 04:28 AM   #3
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Default Re: CSA Mega Midget Racer

Blimey oh riley, that was an expensive MMR!

q1 - Leave it as-is. For starters, the max is 33.33MHz as I recall... The RAM doesn't autoconfig: you have to specify the speed of the RAM via a utility (CSA-MMR). I don't think it supports speeds other than a few predefined numbers, however I'll check tonight

q2 - There are jumpers to configure the wait state that you need to set on the daughterboard. I think it takes care of all this and you don't really have any options.

q3 - I have exactly the same desire. My thought is that we'd have to decompile what the SROM option does within the CSA-MMR command and rework that to load 3.1 off a file. Or some other location... There has been mention of a utility that might be a step towards this called "MMRBoot" on c.s.a.hardware, however I've never found any reference to it apart from one post.

q4 - It might work, however there's talk of AdIDE being incompatible with accelerators (ref amiga.resource.cx...)

Other comments: you will have to do something about the floppy drive in the 1000, as the MMR will physically interfere with it. My plan is to use a 600/1200 drive in there, but I'm unsure of whether this will work. The back up plan is to build a small adaptor which shifts the MMR back by a couple of inches - I think jeff has done this and there's pictures on this very board.

In fact, I think Jeff has tried an accelerator with a 68k CF adaptor...

The decompilation of CSA-MMR could be interesting and could be the best route to 3.1 on there. At least there's two people in the world with the same ultimate plan!

BTW, Mika (the chap who makes the CFIDE68K) has plans for to make an expansion port mounted version like this (but smaller): http://www.amiga.org/gallery/index.php?n=2549=6 - I'm pestering him politely as this would be perfect for me!
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Old 05-11-2009, 04:29 AM   #4
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Default Re: CSA Mega Midget Racer

CZ, All that utility does is take the currently active kickstart and copy it into the SRAM, unfortunately. Hence the plan to see what it's doing and fudge it :-D
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Old 05-11-2009, 06:19 AM   #5
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Default Re: CSA Mega Midget Racer

I have two original CSA mega midget racers in A500. They run just great at 50mhz, that is what they were configured for when I purchased them new.
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Old 05-11-2009, 06:39 AM   #6
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Default Re: CSA Mega Midget Racer

Marvellous :-) - one of mine has a 50MHz coprocessor which is clocked separately, but the 030 itself on mine is clocked at 33.3MHz.
The other one has a 33MHz copro and the 030 is clocked at 25MHz.

I never realied that they sold a 50MHz version - what's the command line on your startup-sequence
csa-mmr srom dram 50.00 ?

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Old 05-11-2009, 07:24 AM   #7
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Default Re: CSA Mega Midget Racer

Wow a quick response from you guys.

amiga92570, are you sure that the 68030 is actually running at 50Mhz and not clocked separately like on my board which has two clock crystal sockets (a 50Mhz and a 36Mhz present)? I mean mine has a 68030 capable of 50Mhz but it isn't actually running that quickly according to the manual (36Mhz).
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Old 05-11-2009, 07:45 AM   #8
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Default Re: CSA Mega Midget Racer

Hi Ben, which manual are you referring to as I can't find a reference to 36MHz at all? (I could have made myself look exceedingly stupid here :-D )
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Old 05-11-2009, 07:48 AM   #9
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Default Re: CSA Mega Midget Racer

What would be really useful is some benchmarks showing memory read/write performance (60, 70 and 80ns fitted). If it were significant enough, it might be worth sourcing the 60ns DRAMs as I see their numbers for ordering all over the shop when googling (whether there is actually stock, I do not know).

If the ADIDE isn't compatible, then I suppose I can use an A590 with the hacks added so the PSU isn't required. Obviously internal expansions look nicer though and I don't even know if my A590, with original 20Mb XT drive and some corrosion, works yet! :-)

That CF adaptor would be awesome but I imagine unless Mika plans on selling these (for a good price to help make it worthwhile), it is not going to be practical for my purposes. I have done electronics design/prototyping with PICs and even made my own PCBs but SMT gives me the creeps (http://en.wikipedia.org/wiki/Surface-mount_technology). Of course that probably means I need to practice it!





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Old 05-11-2009, 07:49 AM   #10
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Default Re: CSA Mega Midget Racer

Quote:
chiark wrote:
Hi Ben, which manual are you referring to as I can't find a reference to 36MHz at all? (I could have made myself look exceedingly stupid here :-D )
Well the manual does say 33 and 38Mhz as options but my (yet to be tested) mega midget comes with a 36.0Mhz crystal installed!
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Old 05-11-2009, 08:43 AM   #11
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Default Re: CSA Mega Midget Racer

The AdIDE will work with the MegaMidget, as well as the Derringer, if it is UNDER the accelerator. I have tested this configuration in an A500. As far as an A1000, I can only assume it will work, or hope :-)
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Old 05-11-2009, 09:20 AM   #12
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Default Re: CSA Mega Midget Racer

LoadWB, can you drop a mail to the good people at amiga.resource.cx in that case, as their information is outdated (http://amiga.resource.cx/exp/megamidget) - I've held off trying a 68k based socket on that basis, however if it works I'll try one from Mika.
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