exxos's Atari, Amiga & retro forum

I have recently got the pre-assembled STE DUALTOS UBE 1.62 & 206 module and ROM from the Exxos Shop for my 1040STe but with it installed I get a white screen the same as if it tries to boot with no ROMS inserted, but working fine with original 1.62 ROMS.

Machine details:

• MainBoard CA401177
• 1Mb RAM (4 x 256kB SIMMS)
• PSU: DVE DSP-508A

Install details (hopefully) as per https://www.exxosforum.co.uk/atari/last/tos/

• Board installed with flat (un-notched) flush to left hand edge by decoupling caps C113/C114
• Reset line to pin 23 on the YM chip
• ROM jumpers set as: W102 (2&3) W103 (2&3) W104 (2&3)

The pins are all making contact from what I can see as I push it into the sockets so have I missed something here or just doing something stupid? :)

When you turn on your STE, press the reset button, does it then boot ?

Nope, get some vertical lines on screen briefly and then back to white.

Sounds more like you have a RAM fault.

The lines are only momentary as it resets, plus the machine works fine with original ROMS.

I've just swapped the 1Mb SIMMS for the 4Mb SIMM kit I got from you instead and it's the same (both sets of RAM are tested fine on old ROM too)

I'm going to check continuity on all the ROM pins top to bottom just in case.

Continuity from bottom of PCB to top of ROM board checks out.

Can I suggest you disable the UBE switcher element and see if it works normally?

In other words disconnect the line to the YM, and desolder the jumper (TS) that enables the UBE Switch.

By doing this you will have just a standard DualTOS adapter. You can then either leave the TOS select jumper open or closed and see if it boots ok.

If it works then you can then take another look at the UBE Switch side of things.

rubber_jonnie wrote: 08 Dec 2019 15:40 Can I suggest you disable the UBE switcher element and see if it works normally?

Removed reset connection and cleared bridge for UBE and no change :(

Just to double check, is the ROM correctly oriented to pin 1 of the socket?

Yup, Pin 1 arrow in socket matches to Pin 1 dimple on top, as does the chamfered corner :)

Incidentally, if this was one of my chips and given the behaviour of the machine with the switcher chip in matches that of having no chips in at all I'd normally be looking to see if I'd actually programmed the bugger in the first place but my MiniPro doesn't list the AT27C4096 PLCC version as a supported chip so I won't be able to read it and check it.