Romswitcher help

[breech]

I bought a romswitcher off ebay for my rev 6a A500, apparently tested & new - which is crap because the cables were missing & torn out so I had to clean the through holes replace them. Anyway, I hooked it up as per the instructions here: http://www.frontiernet.net/%7Ejimdrew/kickstartdocs.zip. I cannot get it to switch using left mouse (Odd-CIA pin8). It's not consistently selecting the far socket because no matter where I place the 2.04 rom it will boot from it - and I noticed that removing the other rom, and holding shift would throw up a guru. Both roms are tested and bootable independently. A pic is attached showing the mods & switcher.

Anyone have any ideas whats going on?

Other mods that may be interfering:
Super Denise
Obese Agnus (2MB) 8375
512k + 512k expansion


* I have insulated the underside of the switcher
* The hookup in the pic was incorrect, i will try pin 25 in the keyboard controller. There is 1.9v on Odd-CIA pin 25, I hope that didn't do any damage..

[Fingerlickin_B]

Not much help...but IIRC there is something different about the A600's ROM socket "wiring"?

Hopefully someone else will chime in soon.

PZ.

[breech]

Update: connecting the control cable to p25 of keyboard chip does not switch it.

Attached more pics, rear of pcb & mystery controller
brown ('black') -> pin5
white ('red') -> pin2

[Arnie]

Are you absolutely sure it's keyboard switching and not a switch?

[breech]

The ebay sale pointed to those instructions. I just tried shorting the cables, nothing.

[Loedown]

I personally would have sent it back if it wasn't new because it was probably sold as new when the previous owner clearly knew it was faulty.

The chip(s) with the tops milled off will most likely be bog standard 74 series chips.

[roy bates]

Originally Posted by Loedown

I personally would have sent it back if it wasn't new because it was probably sold as new when the previous owner clearly knew it was faulty.

The chip(s) with the tops milled off will most likely be bog standard 74 series chips.

yes i agree,it might be a 74ls74(being used as a flip flop) variant.considering its connected to pin 2 and 5.although its only a guess so dont read to much into that.


hmm,if it was a 74ls74 or variant theres no way this was a keyboard switcher,it would be on a toggle switch.

connecting it up to pin 25 of the cia would,well probably kill the poor 74 series part.

[breech]

An update..

I dug out an old 1.2 rom and it can switch (using shift during reset) between 1.2 & 1.3. It seems like the switcher doesn't like the (original) 2.04 rom and selected it regardless of which socket it is mounted in. The seller is being helpful so far and asked for more tests, which I just provided. Hopefully he has a solution for me tomorrow.

[Loedown]

Originally Posted by breech

An update..

I dug out an old 1.2 rom and it can switch (using shift during reset) between 1.2 & 1.3. It seems like the switcher doesn't like the (original) 2.04 rom and selected it regardless of which socket it is mounted in. The seller is being helpful so far and asked for more tests, which I just provided. Hopefully he has a solution for me tomorrow.

The 2.04 ROM comes originally with a wire link between two pins and it needs it for A500 operation and without for A2000 or it's the other way around.

[cosmicfrog]

I had to do the wire in my old A2000 4.x mobo

[breech]

I looked into that but apparently rev 6a a500 doesn't need any 2.04 mods, and it works fine in the original socket. The seller says his 2.04 switches properly on his rev6a. He may be using an NTSC rom though, as he's in the states.

For Rev 6A and above, cut or remove any jumpers from the top of the chip. Align the 2.04 ROM with socket U6 and press firmly down into place. Check for bent pins.

Source: Software Hut

[roy bates]

i didnt know there was such a thing as ntsc roms.

[Jope]

Only 1.0 and 1.1 had separate NTSC/PAL releases. 2.04 is the same for all A500s/A2000s.

[breech]

Ah fair enough. Any more ideas?