My Mac SE/30 Part IV: Upgrade Plans

In Part III of this series I took out (and cleaned) the motherboard and disk drives of my Macintosh SE/30. At that point, I was stuck waiting for the upgrades I’d ordered to arrive. But what upgrades exactly?

As I’ve mentioned before, the SE/30 is one of, if not the, most popular model of compact mac ever made. That’s largely due to its speed and expandability – the SE/30 is essentially a powerful Macintosh IIx crammed into the smaller Macintosh SE case. Both the SE/30 and the IIx use the Motorola 68030 processor running at 16MHz with a 68882 FPU coprocessor.

However, despite the many hardware similarities, the SE/30 has one decided limitation: its ROM is “32-bit dirty”, while the ROM of the IIx is “32-bit clean”. What does that mean? Well, the ROM in a classic mac is essentially a bit of permanent software on a (ROM) chip that’s responsible for booting the machine and interfacing between the system and with the hardware.

I won’t get into the history, but having a “32-bit dirty” ROM means the system is limited to a maximum 8MB of RAM. So the SE/30 can only use 8MB of RAM, while the identically powered IIx can use up to 128MB. This doesn’t matter much if you’re running System 6 (which itself is “32-bit dirty” and can only use 8MB of RAM), but if you’re running System 7, it’s an annoying limitation.

But there’s good news! As it turns out, while the software in the SE/30’s ROM can not be updated, the chip itself is actually on a small removable SIMM board. Same with the IIx. So it didn’t take long for enterprising mac enthusiasts to trying putting IIx ROM boards into their SE/30s, and voila, it actually works! With the swapped ROM the SE/30 can see up to 128 MB of RAM. From what I understand, it was a very popular upgrade, and a big part of why the SE/30 became so popular.

My SE/30’s RAM

With that, let’s return to me and my SE/30. While I want the machine to look cosmetically as original as possible, I do want to upgrade the internals a bit, especially the RAM.

As I mentioned in the last post, my SE/30 has the max factory configuration: 4MB spread across four 1MB RAM sticks. I also mentioned that the original seller claimed that the other four RAM slots weren’t functional. Right off the bat, it seems that I’m already at the limit for this particular machine.

Now, if I could get my hands on a IIx ROM board, I could swap out my four 1MB sticks for four 16MB sticks, bumping the RAM to 64MB. Not the absolute max of 128MB, but still a very worthy upgrade.

However, if it’s hard and expensive to track down vintage macs in good shape, it’s even harder and more expensive to find upgrade parts, especially for popular upgrades and especially for parts taken from other vintage macs. But there’s more good news – we don’t actually have to track down an original IIx ROM board.

Modern ROM Replacements

Enter modern enterprising mac enthusiasts, who have created new replacement ROM boards. There are two options in the market today: the GGLABS MACSIMM and the BMOW Mac ROM-inator II. Both are relatively cheap ROM boards that can be installed in SE/30s, as well as other compatible models. Furthermore, both provide useful “customization” options for how the ROM works.

One useful thing they do is path the ROM to disable the memory test at boot. While the 68030 processor is a beast for its time, running a full memory test on 16, let alone 64 or 128 MB of RAM at boot can take up to a full minute. (For reference, when rebooting my SE/30, as-is with System 6, the machine is back to the desktop almost before the startup chime finishes.)

Another patch adds HD20 support, which is a useful (but older) protocol for hard drives that connect via the external floppy port. While I don’t plan on getting or using an HD20 hard drive, it’s useful to have because my Floppy Emu can emulate such an HD20 hard drive, giving me an easy way to transfer large files to and from the machine via SD card.

Now, it’s here that the two products take different philosophical approaches. The base MACSIMM model stops with just the two patches – no memory test plus HD20 support. There’s also a “deluxe” model which adds a built-in, bootable “recovery” disk, so even if you have no other disks installed, or none of them are booting properly, you can still boot into a working system to troubleshoot your machine.

The Mac ROM-inator II on the other hand, comes in only one model, which includes the recovery disk functionality, but also a lot of other customizations as well. The startup chime, a classic hallmark of vintage macs, has been replaced with their own custom tune. The “Happy Mac” startup icon is replaced with a custom “Pirate Mac”, and the startup menu displays some info like the amount of RAM installed, how to boot the recovery disk, etc. Price-wise, it’s also cheaper than both models of the MACSIMM.

My SE/30’s ROM

I want to upgrade my SE/30’s RAM to at least 64MB and I want the HD20 support. With the Floppy Emu and the SCSI2SD, I don’t think I really need the recovery disk. Also, in keeping with my desire for the machine to look and feel original, I was actually turned off by all of the Mac ROM-inator II’s customizations.

In the end, despite having to pay a higher price, I went with the MACSIMM. It helped a little that the Mac ROM-inator II was out of stock at the time. Also, when I contacted GGLABS to confirm that the MACSIMM did not include similar “stylistic” customizations, he explained that he too preferred the basic setup, though he’d happily reflash his board with whatever alternate ROM image I gave him.

So I ordered the basic MACSIMM module and started looking for more RAM. Thankfully, unlike with the protracted ordeal I had finding RAM for the Power Mac 8600/200, I found a seller with 16MB sticks of compatible RAM quite quickly, and at a price within my remaining budget. Still, I limited myself to only ordering four sticks – I reasoned that without any guarantees that all eight slots worked, I didn’t want to waste any money up front. Plus, other than it being really cool, I still wasn’t even sure I’d find a way to use 64MB at once, let alone 128MB.

Alright, now that the plan’s in place, stay tuned for Part V, where I start actually upgrading my machine.

/jon

Want to read from the beginning? Start at Part I.