[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Analysis of Apple IIGS Prototype ROM 03 with excerpts from firmware source
Antoine Vignau wrote:
> From Apple's Tech info library:
>
> What's the difference between ROMs 341-0737/0748 and ROMs 341-0728/0749 on
> the Apple IIGS 1MB logic boards?
>
>
> Aside from some changes in the Toolbox, there weren't many changes to the
> Apple IIGS ROMs. In fact, that's why Apple doesn't have an upgrade path to
> the new ROMs. It wouldn't be cost effective for the customer.
>
> Copyright 1991, Apple Computer, Inc.
> Tech Info Library Article Number:8815
>
In that case it might not be worth doing alot of work to obtain the image but it would still be interesting. I tend to believe what I "see under the hood" more than what I read. So far I have found two bugs noted in the source that remained in the ROM 03 image:
comment in source:
* Fixed a very old coding error after GetOldEditLine; it was checking the low
* word of a value twice instead of checking both words. I don't think this
* had any actual consequences, but I fixed it anyway.
at address FC/8F00:
028AA 0153 A5 1A lda <OldEditControl
028AC 0155 D0 04 028B2 bne DeactivateOld
028AE 0157 A5 1A lda <OldEditControl ;BUG still present in ROM 03
should be this instead:
028AE 0157 A5 1C lda <OldEditControl+2 ;was missing +2 (3-Mar-91 DAL)
028B0 0159 F0 1E 028D0 beq SetNewEditItem
and at address FF/47E0 in 3.5 disk driver:
F47E0 47E0 00FF47E0 @30 EQU *
F47E0 47E0 A5 45 LDA cmdcode
F47E2 47E2 29 BF AND #%10111111
F47E2 47E2 C9 49 CMP #initcmd ;BUG still present in ROM 03
should be this instead:
F47E4 47E4 C9 05 CMP #cmddefid ;fixed 5/29/91 JOA (was initcmd!)
F47E6 47E6 D0 04 F47EC BNE @35
F47E8 47E8 24 48 BIT cmdscode ; allows special INIT command to skip Sens & MountVol!!
Notice these source notes are the same year as the technote bulletin (1991).
These bugs weren't in the Toolbox. Apple knew the problems but didn't recommend
an update. This just continues to fascinate me - Larry