johnmac@fawlty.towers.oz (John MacLean) (10/05/89)
Did ye all know that in ROM version 01 (the second ROM version we got in Aus) there is a routine that checks for the existence of the expanded ROM containing all the extra tools? I cannot remember the vector off hand - its around $E1/00?? and is one of the first or only unused vectors in the original Firmware Reference manual. On a warm boot this vector is JSLed to and a routine in bank $FE checks for the existence of a string "ROMTOOLS" in some other bank (I think it is $F8). If it is there, then a JSL is made to that bank presumeably to start up the ROM tools, and a second JSL is made to the bank to retrieve a version number? If you want to find this code have a look for the string - I think it is in the first few pages of bank $FE but it about a year since I found this. Shoot me down if this is documented, but I have not seen it ... The interesting thing is that this means that the code for expanded ROMs was at least being tested back in 87 (maybe early 88) when we received the ROM 01 update. It also means that an add on ROM card (attachable to an AE card via the connection for eg) could be made to put all the tools into ROM. Such an upgrade might be more cost effective than a motherboard replacement, and would work with no software changes ... John MacLean -- Internet: johnmac@fawlty.towers.oz.au Phone: +61 2 427 2999 UUCP: uunet!fawlty.towers.oz.au!johnmac Fax: +61 2 427 7072 Snail: Tower Technology 31-33 Sirius Rd, Lane Cove, NSW 2066, Australia.
lvirden@pro-tcc.UUCP (Larry Virden) (10/12/89)
Network Comment: to #920 by munnari.oz.au!csc!ccadfa!usage!basser!metro!ipso!fawlty!johnmac@uunet.uu.net
That sure seems like it would be POSSIBLE for use. The problem is that
Apple has never taken the approach of supporting someone else's product.
There USED to be a few memory cards which supported a ROMDISK option on
their card - I think with some sockets. Are these boards still for sale,
and has anyone contacted them to see if they will be coming out with some
roms? Anyone from Apple have any comments about the feasability of providing
even MORE Apple IIgs ROM 03 compatibility thru the use of the ROMDISK?
--
Larry W. Virden ProLine: pro-tcc!lvirden
674 Falls Place Work: lvirden@cas.bitnet
Reynoldsburg, OH 43068-1614 Aline: LVIRDEN
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