Re: Two ROM 01s?

[Rubywand <rubywand@swbell.net>]

Adam Myrow wrote:
> 
> A quick way to crash my ROM 01 is this.  Type "CALL -1184" from BASIC, then
> press openapple-CTRL-ESC and watch the system puke.  This doesn't happen on a
> ROM 03.
> 
> The reason I'm curious about this apparent bug is that my ROM 01 gives me a
> lot of trouble when trying to use any utility by Tom Larson that includes the
> Browsking Minibrowser.

> ....  Recently, I saw a post about two
> versions of the ROM 01.  It was in regards to a certain mouse that only worked
> with the later version. .... Any idea how to tell which ROM 01 I have ....


     It sounds like you are talking about the ADB Controller IC mod which Apple 
introduced in its later-1987 ROM-01 GS. (Too many of the earlier ADB Controller 
IC's turned out to be glitchy over a range of room temperatures.) This was a 
hardware mod. (I do not know whether a corresponding firmware/ROM mod was done.)

     The ADB Controller changeover is not mentioned in the early version of the 
IIgs Harware Reference Manual (1987).  According to the manual, the GS uses an 
M50740 ADB IC. In a later edition of the manual, the ADB IC for the "256kb GS" 
(ROM-01) is still the M50740; for the "1MB GS" (ROM-03) it is shown as the 
M50741.

     Meanwhile, the ADB IC on our Woz edition GS is labeled (on the IC and 
motherboard) as "344S0048-A". Our machine has the ROM-01 Upgrade; but, since the 
IC is soldered to the motherboard, the upgrade did not include an ADB IC 
swap-in.

     Could ADB IC differences explain problems with a piece of software? 
Certainly, In the case of the Kensington TurboMouse ADB trackball, the 
difference between the older and newer ROM-01 ADB IC's was significant-- so, TM 
will not work satisfactorily on older ROM-01 machines.

     Very few pieces of software communicate directly with the ADB Controller. 
Software which does and which expects to find an M50740 or M50741 ADB Controller 
might well be expected to work incorrectly on a machine with the older 
controller whether or not there are any differences in ROM code.  


Rubywand