exxos's Atari, Amiga & retro forum

I have a Atari STE with 4MB RAM that I can't get to boot from 32 pin eeproms that have TOS or EMUTOS written on them. The computer works fine with the regular 28 pin ROMS that have TOS 1.62 on them. From gotek floppy emulator I can load different versions of TOS from a .st file. The 4MB RAM passes yaart memory test doing multiple passes.

On the STE mainboard I have removed the zero ohm link resistors from W104 and W102 and replaced them with two sets of three jumper pins. So when I have the two TOS 1.62 ROMS plugged in the W104 and W102 jumpers are set to 2-3. And with eproms plugged in it is 1-2. I have not changed W103 with its link from 2 to 3.

I brought some Winbond W27C010 eproms from ebay because I can't get them new. Within Steem emulator and using romutil - split_it.prg I split a 256KB TOS or EMUTOS .img file into two high and low 128KB files. Then I flash these two files to two high and low eproms with a Minipro TL866A programmer.

When trying TOS 2.06 hi and lo eeproms there is a white screen and where the Atari logo should show there is instead a black box. A few seconds after that I see 3 bombs - address error.

Trying EMUTOS hi and low eproms I get its EMUTOS intro screen with information about the computer. Then that is replaced by 'EMU TOS 1.1.1' and after that I get a 'Address Error' screen with text including 'misc=4e72 opcode=4e73', 'addr=ffffffff'.

With a multimeter doing continuity tests, referring to a Atari STE schematic pdf I have succesfully tested connections between pin no 2 on both of the 32-pin ROM\EPROM sockets to pin 2 on W104. There is a connection between pin no 24 on both of the 32-pin sockets and pin 2 on W102.
There is a connection between WO102 pin 3 - W104 pin 1 and pin 48\A17 of the 68000 CPU.

I am a novice at electronics so I might have missed something. Maybe there is a 74 logic ic that has a fault which is not a problem for the two 28 pin ROM chips to work but creates a problem with the computer has 2 x 32 pin eeproms plugged in.

xav2075 wrote: 09 Oct 2021 06:56 When trying TOS 2.06 hi and lo eeproms there is a white screen and where the Atari logo should show there is instead a black box. A few seconds after that I see 3 bombs - address error.

Sounds like you have the jumpers set for 28pin ROMs not 32pin.

Correct settings for 27C010 are:
W102: 1+2
W103: 2+3
W104: 1+2

I also attach split ROM image files.

Here you can see I have removed the zero ohm resistors from W104 and W102 and replaced them with pins and jumpers.

For the pair of 28-pin TOS 1.62 ROMs W104 and W102 are both jumpered 2-3. The Atari STE boots fine with this.


And this is for the pair of Winbond W27C010 32-pin eproms that have TOS 2.06. W104 and W102 are both jumpered 1-2. The Atari STE fails with 3 bombs - address error.

tzok wrote: 09 Oct 2021 10:34 Correct settings for 27C010 are:
W102: 1+2
W103: 2+3
W104: 1+2

I also attach split ROM image files.

I wrote etos256uk_HI.bin and etos256uk_Lo.bin from that zip file and it works! Thank you :D

So the SPLIT_IT.PRG I was using is defective. Now I need to find a working 256KB hi lo rom file splitter.

use rommix from the pinatubo package ...

https://www.schwingen.org/atari/atari-software/

# Puffergr”že setzen
bufsize 256k
# Directory setzen
chdir c:\rommix\

load etos256.img 0 256k all -> 0 all
save ee.img 128k <- 0 even
save e0.img 128k <- 0 odd

You also have ROMSPLIT that I have used and works.

After some googling I found I could use WinHex to properly split a TOS .img file into two hi lo 128KB files for writing to eprom. Unregistered version of WinHex allows up to file sizes of 200KB to be saved which is not a problem for splitting a 256KB file and saving it in two 128KB parts. The first saved file is the hi one and the second is the lo file.


Now I have working TOS 2.06.

Without any googling, I may tell you, that you can do the same with the MiniPro/XGPro software ;) You only have to remember that "low byte" will be high ROM, and "high byte" will be low ROM, and it is due to the different endianness of the Intel and Motorola CPUs.