tnt23 Posted August 18, 2009 Share Posted August 18, 2009 Hello all, I've got a Mega ST4 with German TOS in it (6 ROM chips). I would like to replace it with English version. Sysinfo says it is version 1.02, and I've thought about upgrading to 2.06. I have ordered a couple of 27C010 chips, and now am slightly confused as these are 32-pin DIP chips, and ROM sockets on ST4 take 28-pin DIP ones. I understand I will have to switch some wire jumpers (W2, W3 and W4) and possibly install U12 chip which is missing on my motherboard. Could anyone please give me directions on how to wire 2 32-pin chips for this setup? Thanks! Quote Link to comment Share on other sites More sharing options...
simonsunnyboy Posted August 18, 2009 Share Posted August 18, 2009 TOS 2.06 requires an entirely different address range than 1.x. Apart from physical problems fitting the chips, you will need additional decoder logic to run TOS 2.06 in a Mega ST. Quote Link to comment Share on other sites More sharing options...
tnt23 Posted August 18, 2009 Author Share Posted August 18, 2009 TOS 2.06 requires an entirely different address range than 1.x. Apart from physical problems fitting the chips, you will need additional decoder logic to run TOS 2.06 in a Mega ST. Well, I won't mind running English 1.04 Are those GAL chips in IDE interface for Mega STs about this additional decoding? Quote Link to comment Share on other sites More sharing options...
tjlazer Posted August 18, 2009 Share Posted August 18, 2009 Hello all, I've got a Mega ST4 with German TOS in it (6 ROM chips). I would like to replace it with English version. Sysinfo says it is version 1.02, and I've thought about upgrading to 2.06. I have ordered a couple of 27C010 chips, and now am slightly confused as these are 32-pin DIP chips, and ROM sockets on ST4 take 28-pin DIP ones. I understand I will have to switch some wire jumpers (W2, W3 and W4) and possibly install U12 chip which is missing on my motherboard. Could anyone please give me directions on how to wire 2 32-pin chips for this setup? Thanks! I have a set of TOS 1.4 for the Mega ST 6 chip for sale, are you interested? $30 shipped. Quote Link to comment Share on other sites More sharing options...
tnt23 Posted August 18, 2009 Author Share Posted August 18, 2009 (edited) I have a set of TOS 1.4 for the Mega ST 6 chip for sale, are you interested? $30 shipped. Thanks tjlazer, I'll first try to use those 27C010 chips I've already ordered Edited August 19, 2009 by Tempest Quote Link to comment Share on other sites More sharing options...
simonsunnyboy Posted August 19, 2009 Share Posted August 19, 2009 TOS 2.06 requires an entirely different address range than 1.x. Apart from physical problems fitting the chips, you will need additional decoder logic to run TOS 2.06 in a Mega ST. Well, I won't mind running English 1.04 Are those GAL chips in IDE interface for Mega STs about this additional decoding? Depends..some might incldue support for TOS 2.06 right away because TOS 2 is needed to boot froma n IDE drive. But absically it shoudld ecode onyl the IDE address range Quote Link to comment Share on other sites More sharing options...
tnt23 Posted August 20, 2009 Author Share Posted August 20, 2009 OK, what is this additional decoding logic needed for 2.06 to be put into MegaST? While waiting for my 1M chips to arrive, I've dug out a bunch of old 512K chips to try with English TOS 1.02. As these are twice as big as original 256K ones, there probably could be a way to use 4 of them instead of 6. The W2/W3/W4 table from the service manual only mentions 256K and 1M chips. Looking at the schematics I can see that W3 and W2 are responsible for A15 and A16 address lines, respectively. For 512K chips I guess only W3 can be switched to 2-3 position? Quote Link to comment Share on other sites More sharing options...
Thorsten Günther Posted August 22, 2009 Share Posted August 22, 2009 I found full instructions here: http://atari4ever.free.fr/hardware/zip/tos206up.zip Other than the uRL, the instructions are not in French (but I hope you won't mind them being wrtitten in English anyway). Thorsten Quote Link to comment Share on other sites More sharing options...
tnt23 Posted August 22, 2009 Author Share Posted August 22, 2009 I found full instructions here: http://atari4ever.free.fr/hardware/zip/tos206up.zip Other than the uRL, the instructions are not in French (but I hope you won't mind them being wrtitten in English anyway). Thorsten Great piece of knowledge, thanks! Quote Link to comment Share on other sites More sharing options...
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