Analogic STE ROM Switcher

[JezC]

Hi,

While trying to sort out some of my STE's, I finally pulled apart one of my oldest (external blitter) & found that it contains an Analogic ROM switcher (with TOS 1.06 & 2.06 installed, both EPROM versions).

I'd noticed before that it worked fine with the 1.06 TOS enabled but rebooted or froze after a few minutes if TOS 2.06 was selected.

Does anybody know if I can just remove the EPROMs from this board & fit them directly into the motherboard ROM sockets?
I suspect that I may need to fettle the contacts in the ROM sockets a bit first as the switcher board appears to have pretty wide pins...

[alexh]

It depends which EPROMs they are and what the motherboard jumpers are set to.

Probably will work.

[JezC]

Thanks @alexh - I'll check on EPROM versions plus motherboard settings & post back later today (time permitting).

[alexh]

The jumpers are not fitted. They are just solder bridges. Meaning you can't change them without soldering. Which is why I normally use 27C1000 EPROMs because they match the default jumper setting

[JezC]

They're AMD 27C010 EPROMs...the TOS 2.06 are 155 speed while the 1.06 are 200.

W103 had no short but both W102 &. W104 have 2 bridged to 3.

Not sure if it matters but E0-E7 are not bridged either.

I'll upload a photo later

Edit: photo attached...

STE_ROM_jumpers.PNG

[alexh]

Your motherboard seems to be wired for the 27C1000? This is not surprising as this is the setting they came out of the factory for mask ROMs.

W102 = W103 = W104 = position 2-3

STETOS.gif

I believe that means you can't plug the EPROMS in directly. You'd have to solder the jumpers to the correct setting for 32-oin 27C010

[JezC]

Thanks @alexh.

Given how loose the EPROMs feel in the original motherboard sockets, I will have to swap those for new versions before I can completely ditch the switcher...and I'd rather get a bit more practice honing my skills before I tackle that!

So, as a temporary solution, I've swapped the TOS 2.06 EPROMs over to the positions previously used for the TOS 1.06 & re-fitted the board.

That now seems to allow me to run the TOS 2.06 for a much longer period (it ran OK for 90 minutes earlier this morning, currently testing how long the 1.06 ROMS will work for in the other sockets...)

I'll bookmark this info for when I feel prepared to replace those sockets though!

:thanksblue: