meltdown wrote:Thanks for posting.
The problem is that it stays black all the time.
The afterburner was used in another falcon for years with no problem.
Unfortunately i don't have that Falcon anymore.
The AB was savely stored for a few years when i decided to build it again.
Now it is in another Falcon but it stays completely dead.
I remember having the same sort of problem when it was build in the first time
but i can't remember what i did to solve it then
I did see a picture of an AB which had a component soldered over one of the mach chips.
It looked like an modification.
My AB doesn't have that so i wonder if anyone can tell me what that is.
meltdown wrote:I did contact him but he also has forgotten about most details like i did.
It's just too long ago that we build in all kinds mods and accelerators
I'm getting old
The one who knew was Douglas Little but he has vanished.
Come to think if it i must have modded more than 100 falcons in the past
meltdown wrote:I used to have an Atari repair shop that's why i modded so many of them.
I do have some collectables left from those days.
If anyone is interested in some nova graphic cards for the falcon?
meltdown wrote:I have two of them.
The sale one those are pending right now.
If they fall through i'll let you all know.
But they don't come cheap.
Bidding starts at €200
meltdown wrote:The one who knew was Douglas Little but he has vanished.
... "Bermuda Triangle" of famous Atari people...
dml wrote:- the machine only powers on reliably 90% of the time (powering on a 2nd time always works)
- when it doesn't power on 1st time, the screen is black, no sync. like a device is stuck in reset. I haven't verified this yet
- hitting reset doesn't help, although the monitor sync does change while the reset button is held (still black screen, but monitor signal/response changes)
- once running, the machine will only soft-reset 70% of the time. power off is usually less trouble.
dml wrote:- can't seem to find more than 16mb in each simm bank, regardless of simm size used
- 16mb seems to be mirrored/repeated after each bank
- there are 2 jumpers - JP1/JP2, each with 3 pins. purpose unmarked.
- the machine only boots with 1 permutation of jumpers (jumper across 2&3 of JP1). black screen with any other combination.
dml wrote:- there is a 68881/2 emulation driver (likely based on the Motorola support software) which uses the illegal instruction exception to emulate the missing FPU instructions of a real FPU. I find this crashes 20% of the time the machine boots up - possibly because it's not initializing it's own memory properly but I never debugged it properly. it's not essential anyway unless trying to use 68020+881 compiled apps, in which case it works fine so long as it gets past bootup.
dml wrote:- from my memory of things, pins 16 & 17 on the 68030 need to be lifted and 'dealt with'. these are the bus grant control lines that allow the 68030 to operate as a busmaster. these are tied away and the 68040 is given control as busmaster. it's possible to switch between them (there's a page on the web describing this) which some people will find useful - but I haven't found the need for it myself, mainly a compatibility option for stock-falcon mode.
- a bunch of wires need soldered to the GAL chips and some other locations. (I'm going to take a photo of the wiring soon and stick it on my site). these terminate in a plug which fits onto a small header on top of the AB40.
dml wrote:- AB40 is compatible with nemesis because the latter is just a bus clock and video clock replacement and buffer. I had success with a 20mhz/40mhz combination, but higher and something gets upset. possibly the fastram or the 040 itself. it's a good idea to find fast simms (60ns, or better still <=50ns)
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