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ST Newbie, MegaST2, TOS upgrade, bombs, Ultrasatan

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Hello everyone! I'm a bit of an ST newbie. Grew up on 8 bit Ataris then went DOS. I've owned an ST or two in the past but ended up giving them to friends. I support historical computing, and am working hard to get a Mega 2 on long term loan to me rocking 100%.


I purchased the Ultrasatan dual SD card board, and the adapter for the MegaST2 ASCI port. I plan to mount it to the underside of the metal shield, exposing the SD cards out the back expansion port cover. But I'm not there yet.


First I decided I need to bring the machine up to later TOS version to support formatting disks as DOS. The floppy on my machine is flakey, and I figure I have a better shot at preparing disks for it if I can format them on the system then take them to PC. Also I believe the higher version is needed for hard drives.


I burned the high and low portions of the 2.06 US ROMs to a pair of 27C010 eproms. I erased them, then used a Needham programmer and the software's split function to split the image. I wired them up following this: https://docs.google.com/file/d/0B16K0ocKfoi6aVltVHRWMUNxVEE/edit?pli=1


In my case, pin #30 on both chips is still down in the socket. Other pics I saw online seemed to indicate this was okay.


I tied the wire that goes to CPU pin 45 on diagram to the fake-resistor at W2.


Jumpers W2 and W3 are both still in place, and jumper pins 2 to 3.


My system originally had 2 proms in the 6 sockets.


At first boot attempt white screen, no disk seek.


I reversed the two chips (hi/lo sockets) and now it acts more like a ST when booting up. The floppy spins for a second or two.


But then I get 8 bombs. This says there be some ROM access, but not working.


Any thoughts?

Edited by telmnstr
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Before going in it, you should do some research, reading around. In Mega ST and ST machines you can not use TOS 2.06 without extra logic circuit. Top is 1.04.

Here are some (advanced) solutions for it, and even better thing, multiple TOS versions: http://atari.8bitchip.info/flashest.php

Multiple is best, because TOS 2.06 is not good for gaming.

Btw, considering floppy formating, TOS 1.04 is fine. Or better said, TOS version is irrelevant, because there are floppy formatting programs which do it much better.

For mass storage, so UltraSatan TOS 1.04 is minimal reasonable requirement. With 1.02 there are some extra limitations, and less reliable, slower work.

2.06 is little better with mass storage, but 1.04 is close to it.

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Ah okay! I found the decoder logic but was thinking that was for the 520/1040 and not needed for the Mega2.


The factory rom set I have is 1.2 which is really 1.02.


I guess I can re-program the chips with 1.04 and roll with that. If it's better for games and gets me ultrasatan support, I'm happy!

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Okay, I burned 1.04 US version into a pair of AM27C010 eproms. I used the split function in the burner software as the file I found was a single ROM.


Wired as before, and in my case I'm getting a disk seek on power on followed by what I believe is a reboot over and over. When I lifted one of the W jumpers it crashed with lots of bombs, and I'd imagine the bomb graphics data is stored in the eproms so...



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I have the W2/W3/W4 all set the way they were default which set it up for having two chip TOS versus 6.


So it hit me today and I did some research. I followed the gif file online but did NOT have pin 24 on the 27C010 (pin 22 on socket, A16) bent up and connected to GND.


Pins 1/32/31/30 are all tied together, 30 down in the socket, tested and there is around 4.9VDC here.


Pins 2 on each eprom are tied together, then tied to what would be pin 22 in the socket (via jumper W2)




When I got home I excitedly did pin 24 to gnd, 24 lifted to both chips. Fingers crossed, powered it on and....


4 bombs. then it will reset and give 6 bombs.

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You tied pin 2 with 22 ? That's serious error. Pin2 is A16, 22 is /CE


Sorry, on the original socket pin 22 is A16. So that gets tied to the EPROM (27c010) pin #2 which is A16. It's really pin 24 on the eprom that is left out of socket, and the socket underneath is OE or Output Enable.


The good instructions I found were from a document called TOS104UP.ENG


I guess I can try blanking them and getting the TOS from a different source. The problem is with all the soldering on the chips it makes it a PITA going back to repogram them then retry. Project for this weekend.


Finding a known good split set of images would be good.

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Here is what I did (breadcrumbs for those that follow):


Not trusting the NEI Eprom programming software (more so my skills with it), I setup Hatari and booted TOS 1.04 on it. I used the GEMDOS hard drive to point to a folder and threw the contents of the TOS104 upgrade package in it. This includes romsplit and romdump. The romdump threw out 6 files, which is awesome but I was after 2. So I threw the TOS104 image into the folder and then used romsplit. From there I took the output over to the eprom programming software in Windows and wrote the roms. At this point it worked.


I will post the 6 split files and the 2 split files in a bit.

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