On Thursday 07 November 2013, you wrote: > On 2013-11-07, at 00:39, Groepaz wrote: > >>>> Is there a reliable, software way of recognising ROM areas of a 1541 > >>>> (all models)? I mean without knowing what kind of ROM is actually > >>>> installed. I assume that all of them have to cover up to the end of > >>>> 6502 address space (if not for anything else then at least due to h/w > >>>> vectors) but what about the starting point(s) and what if there happen > >>>> to be some non-contiguous chunks? > >>> > >>> not sure if i understand the question correctly.... but to find out if > >>> there is rom or ram at a certain address, write to it and see if the > >>> value changed? (backup/restore the original value ofcourse) > >> > >> Well, finding RAM would be as easy as you wrote. What is needed though > >> is to distinguish ROM from all other (than ROM) types of things that > >> may dangle around the corners of address space. Not only RAM. Those may > >> be RAM but also e.g. port chips, gaps, unconnected address ranges.. > > > > it would be easier to give an advice if you'd tell what exactly you are > > trying to do.... > > NP - I once wrote a simple drive-ROM dumper program, which works fine as > long as I modify it every time a different ROM layout pops up. Which is > of course that I need to know the layout in advance. Which means either > knowing what's inside or opening, checking, analysing, ... I am thinking > (wishfully - probably) of making the program universal in the sense that > it could detect ROM areas itself. > > > I have only ever needed something like that to find out how much RAM > > is installed in the drive and where it is located - all other info is > > known anyway (like location of i/o chips). > > Not really. DD3 equipped 1541 is a good example of a situation when this > does not hold true. It has different I/O location (the parallel port PIA), > different RAM size/location and different ROM size/location. but that is fairly easy to detect by simply querying the dos error channel, isnt it? so well, what i'd do in the drive would be (in this order) - check the error channel/poweron message. fortunately those drive extensions that added more than just a different ROM were not cloned a lot, so this should give a good hint on wether there is someting like dolphin dos 3 - do a ram/rom check. after that you know for certain what cant be ROM because it is either RAM or i/o (ie, a value written can be read back) - do empty i/o check, ie read blocks and check for $ff - probe for i/o chips at known locations additionally, maybe try to find some specific ROMs at known locations and check by checksum - things like dd3 should be detectable that way -- http://www.hitmen-console.org http://magicdisk.untergrund.net http://www.pokefinder.org http://ftp.pokefinder.org If you want to have creative workers, give them enough time to play. <John Cleese> Message was sent through the cbm-hackers mailing listReceived on 2013-11-09 01:00:02
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