Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!cica!tut.cis.ohio-state.edu!snorkelwacker!spdcc!merk!alliant!linus!nixbur!nixpbe!andreas From: andreas@nixpbe.uucp Newsgroups: comp.sys.atari.st Subject: Re: Piggiback ROMs (2 TOS versions Message-ID: <24100004@nixpbe> Date: 23 Oct 89 10:39:00 GMT References: <2644@iscuva.ISCS.COM> Lines: 20 Nf-ID: #R:iscuva.ISCS.COM:-264400:nixpbe:24100004:000:1033 Nf-From: nixpbe.uucp!andreas Oct 23 11:39:00 1989 /* Written 3:32 pm Oct 19, 1989 by lawrence@techpub1.UUCP in nixpbe:comp.sys.atari.st */ /* ---------- "Re: Piggiback ROMs (2 TOS versions " ---------- */ In article <3619@netmbx.UUCP> hase@netmbx.UUCP (Hartmut Semken) writes: >In article cmm1@CUNIXA.CC.COLUMBIA.EDU (Christopher M Mauritz) writes: >>PC Ditto v3.01 will NOT work with TOS 1.4. I forget what the error >>says, but I think it was something like: "Does not work with this >>version of TOS" or something to that effect. Too bad there isn't a way >>to piggy back the two versions of ROMs and have a hardware switch >>between them. > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Of course there is a way to switch between two version of TOS ! Use 27512 instead of 27256 and copy the first version from 0000 to 7fff and the second from 8000 to ffff. Now you can switch the two versions by connecting the upper adress line A15 (Pin 1 ?!) of all EPROMS to VCC or ground. It works fine ! CU :-) Andreas