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I need a Levco Monster Mac ROM image


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Hi -

 

I have a 128K Mac with a Levco Monster Mac 2MB upgrade card installed in it, and somewhere over the years the covers on the EPROMs on the Monster Mac card have come off... and now the machine comes up to a sad mac icon with an error code of 0180D7; which my brief google search indicates that it's failed a ROM test - unsurprising considering the lack of UV protection on the EPROMs.

 

I don't think the original Apple mask ROMs (they are mask ROMs, aren't they? Not EPROMs? They have no window on them...) are bad; just the EPROMs on the Levco board - so what I need is an image of that - but, the way I think the board works is it overlays the first 4K of the ROM address space with what is on the Levco board; so a standard ROM image obtained from software running on a working Monster Mac should have the data I need in it... well, I hope, anyway.

 

So - can somebody with a working Monster Mac card run a ROM image program (such as CopyRoms http://www.gryphel.com/c/minivmac/extras/copyroms/) and post the result?

 

Although, any other ideas would be welcome also...

 

:b&w:

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I would try using the rom's out of a plus, i have a MacGusto II board in my 512k (which adds 2mb more ram, scsi and a 68881) and it uses the rom's from a plus.

Unless there is anything really unique about the levco board i'd guess it had plus rom's in the first place

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Two things come to mind:

 

1) Well... they have done something; as the machine used to boot with a modified happy mac icon - it had two pixels added, to look like fangs (i.e, it's a "Monster Mac" - so...); and there are four ROMs in the machine - two on the main logic board itself; which appear to be standard Mac Plus ROMs; and two EPROMs on the Monster Mac board (what appears to be Intel 2764 chips - so my earlier mention of overlaying 4K should actually be overlaying 16K of the ROM image... I think). I suppose it's possible that the boot icon was all they did, but I tend to doubt it... that's a lot of trouble to go thru for just an icon (two EEPROMs, and whatever PALs or whatnot were needed to perform the address overlay operation).

 

2) Reading the source for CopyRoms, it looks like it won't work out-of-the-box for this; as it only dumps the ROMs that it knows about. Consequently, I'm going to have to cook up a short program to do it. I've just (in the past 10 min) gotten a C compiler working in Basilisk II, so it shouldn't be too much trouble. I'll post it when I get it done.

 

 

 

:)

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  • 1 year later...
On 5/25/2016 at 8:28 AM, max1zzz said:

I would try using the rom's out of a plus...

Unless there is anything really unique about the levco board i'd guess it had plus rom's in the first place

The 128K Plus ROM is not likely going to work. The original Levco MonsterMac modified the 64K ROM to relocate the screen buffer to be higher up in RAM, allowing for contiguous memory for application heap. See Macworld February 1986, pp 114-119.

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  • 1 year later...

The Levco ROMS in the Monster Mac were specifically designed so that no special software was needed for the upgrade to work.  The EPROMS shipped should have had stickers on them to protect from UV radiation.....  

 

The Levco Monster Mac ROMS took control of the boot sequence, copied the original roms to 32 bit RAM space, modified the 'hardcoded RAM limitations' in the original roms (also modifying the boot icon to have some fangs... aka monster...) , and then mapped themselves out of user space.... allowing the mac to then 'boot' from the modified roms, with the modified rom.  During proper running, the Monster boot roms should never be seen.  The only way of copying them would be to simply remove from the socket and copy using a prom reader... :(  

 

Sorry about that... and.. I no longer have access to the source or the binary of the roms......

 

 

 

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I would imagine a number of us here, including myself, have EPROM reader/writers. My reader/writer can handle up to 4 MB chips. If someone can provide the ROMs I could easily read them and write a set of new ones. Or if someone can provide me with the images of those ROMs, I could also program a new EPROM as well.

Edited by Paralel
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