Recent content by David Cook

Here you go

Also noteworthy, the IIvx using a different system enabler than the Performa 600. Make sure you have both enabler 001 and enabler 304. https://www.macintoshrepository.org/505-macintosh-system-enablers So, if the cache is being enabled in that code (likely), it is critical that the System...

I notice R146 is different between the two board images. It exists on yours but not on @Fizzbinn's board.

Using TechTool or a similar utility, what machine ID does your computer now think it is? The IIvi, IIvx, and IIvm/Performa 600 all have different IDs and thus might be executing different ROM/OS code to enable the cache.

Thank you. BTW, I based my 5126 analysis largely on the PowerBook 100 schematic that appears on your macdat.net link. I then compared it to my 5126 motherboard to be sure. The 5120 recreated hybrid schematic largely reflects the 5126 analysis. Input voltage (6.3B or 7.5V) comes in through RC3...

Let's talk through this using @techknight's video as an example. What could have caused this particular board to be destroyed? It is a 5126 (backlight) with bluing of the power transistors and holes blown in the AC logic chips. (We will assume this is non-abuse unintentional damage. That is...

Thank you!

It looks like the jumpers follow a predictable binary pattern EO=+1MB E1=+2MB E2=+4MB E3=+8MB E4=unknown So, to get +8MB (9 in total with motherboard 1MB), pull jumper E3. To get +7MB (8 in total), keep E3 but pull E2+E1+E0. This explains why the board with 2 megabytes already soldered to it...

That's wonderful news! Congratulations. Your persistence paid off.

Yes. For 8 MB, I moved E3 to E1. So, all jumpers populated except E3. I will play with it further to figure out how to make it 7 MB for use in the 5126. I believe the RAM slot is limited to 4 MB (recent recreations use an extra wire to provide more). Additionally, the system provides the...

As a workaround, adding a >=1MB RAM disk in the Portable control panel seems to prevent crashing. The error is a memory manager error. That's suggests a bug or limit in System 6 beyond 8 MB. I tried using System 6.0.8L without success. I wonder whether a Macintosh LC with > 8MB will crash. I'm...

I have soldered on all the RAM. It works great in System 7.1 on a 5120 Portable. It shows 9MB total and passes all the memory test applications. However, in System 6.0.8, it crashes when doing something as simple as displaying the About box in the Finder. I recall reading about a solution for...

I just bought a Dynamic Engineering Macintosh Portable RAM card with 2 MB of RAM installed. I also purchased new old-stock Toshiba TC 518512FL-80 PSRAM chips to bring the card up to 8 megabytes. My plan is to use this on a 5120 (non-backlight) Portable. The jumpers on the 2MB card are all...

From your expression of concern at the start of this thread, I related to how you felt about being the possible cause of damage. We've all been there. The logical side of us knows that these old things are going to break once in a while, and that we fix more than we harm, and that it is better...

Holy moly! Check out that second picture from @Oelmuvun. I did not expect so much grime/tarnish.