My comments at the bottom. >Date: Sun, 1 Aug 2004 17:46:45 -0700 (PDT) >From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
>I have had diffiuclty finding a IIsi or IIfx rom sim >to place in my SE/30. I have a IIsi, but the rom bank >is blank, so it must be soldered on the motherboard >somewhere. (Why is there is an empty rom slot?) In >the past, I have used a program to "copy" the rom of a >Macplus to use in a game simulator on a PowerMac >(i.e., Macmame). Would it be possible to use this >program to copy the rom from a IIsi and use it in an >SE/30? Could that soft "rom" be copied onto a blank >rom? <Gamba (who seems to have vanished, though his website is still up, <thank goodness) and I did in fact build a ROM SIMM, copying the <contents of the IICI ROM to blank chips and installing them on a ROM <module circuit board. This successfully worked in an SE/30. The <same could be done with a IISI or IIFX <It was a fun experiment, however, we ran into one significant (for <us) obstacle. The ROM SIMM circuit board is ~.050" thick. The <standard thickness on today's circuit boards is .063". So it's <almost impossible to find .050" circuit board. In our case, Gamba <filed the board down to the proper thickness by hand, which was <difficult, time consuming and not anything that he wants to repeat <(nor that I would like to attempt). <<Significant obstacles for other folks would be extracting the ROM <code and getting it programmed into chips properly. In our case, I <desoldered the ROM chips from a IICI board, read their contents on a <chip programmer (a specialized piece of hardware) and then programmed <blank flash memory chips with the contents. I also determined which <data pins on the chips would connect to which pins of a ROM module. <Then I sent the chips to Gamba, and he designed, etched and <fabricated the ROM module board (printed circuit board), soldered <down the chips and tested the assembly in a IICI (using the ROM slot) <and in an SE/30. <We also used a program to copy the ROM code directly to floppy (as <the poster suggests above), which I then compared to what we <extracted directly from the ROM chips. At first, it appeared that <there were differences, putting us in doubt of the usability of the <ROM extracting program. However, a later check seemed to indicate <that the two methods yielded the same code, so perhaps I made a <mistake on the first comparison. I'm still a little dubious about <the ROM extraction program, though, in theory, it should work fine. <Finally, the ROM code is interleaved across four ROM chips. So the <first byte of the ROM code is stored on the first chip, the second <byte on the second byte, etc. then the fifth byte is stored on the <first chip, the sixth on the second chip, etc. <If you extract the ROM contents using software, then you need some <way to spread every fourth byte across chips. Many of the chip <programmers have this ability included in their software, but it <could be an issue. <The primary thing, though, is that you need access to a chip <programmer, to get the code onto blank chips, and you need the <ability to build a circuit board that will plug into the ROM SIMM <socket, hold the programmed memory chips, and connect everything up <properly. <Jeff Walther --------------------------------- Jeff, I was wondering if I could modify a SE/30 ROM to put the chips you programmed on them? What do you think? johnsn -- Compact Macs is sponsored by <http://lowendmac.com/>. Support Low End Mac <http://lowendmac.com/lists/support.html> Compact Macs list info: <http://lowendmac.com/lists/compact.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/compact.macs%40mail.maclaunch.com/> --------------------------------------------------------------- >The Think Different Store http://www.ThinkDifferentStore.com ---------------------------------------------------------------
