Could you put this on a 1xx machine? Or would that not work at all?
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We've made some quality of life improvements to the Trading Post. More info here.
How to: upgrade a 520/540 to a 550c ROM
- Thread starter croissantking
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100% agree. In fact next round I'll probably also switch from an uncompressed disk to FC8b so we can squeeze more stuff into that drive.
They use a different ROM, so it wouldn't work with this particular ROM unfortunately. You'd have to start from scratch with the 160/180 ROM. Also not sure how much space is available for a romdisk on those!
That makes sense! Thanks for satiating my curiosity!
Yeah mostly. Although I've had really bad luck getting EPROMs from eBay, I tend not to really even look at those anymore if I can find an EEPROM brand new.
I got my pair of MX29F1615PC chips off ebay, they're clearly used (despite being advertised as new). I hope they work. Do you have a source for new parts?
BTW, @demik found a prototype boot chime in the Blackbird ROM. It's the same one heard in the training video, here. It's 44.1KHz stereo, so likely specially made for the 500 Series which apparently was the first Mac with 44.1KHz sound output.
Could we try out this chime in our custom ROM @frontein1? It's located between 0xEC000 – 0x137000.
Could we try out this chime in our custom ROM @frontein1? It's located between 0xEC000 – 0x137000.
Hmm, this is an interesting discovery. Yes I bet we could intercept this. It looks like it is in both the 540c and 550c ROMs. I'll look into it
Yep, eBay for me too really. At $20 for a batch of EPROMs, worst case is I file a claim with eBay and will eventually get some sort of refund. But I did get a really nice batch of MC29F1615PC-90s from eBay recently. I specifically went for the 90ns variety as I think that was the fastest available. (Although 10ns probably doesn't really mean anything, especially if the ROM timing is closer to 120ns anyway)
Here are the ones I bought, looks like the seller still has some available:
This is funny, I started up my bench PowerBook today and was no longer booting into the ROM disk automatically. Holding down R seems to work if I do want to boot to ROM.
OK lol interesting, maybe helps reinforce possibly the PRAM flag.
I mostly had the new ROM+DISK image ready to go. I'm looking at changing the hook for the boot chime to point to that hidden one. But I can probably have something ready for you to test later today. It's a pretty big change though, with the new driver, an FC8b disk, and the boot chime change. Do you want to wait until you have your PCB and sockets setup so you don't need to unsolder/resolder?
I mostly had the new ROM+DISK image ready to go. I'm looking at changing the hook for the boot chime to point to that hidden one. But I can probably have something ready for you to test later today. It's a pretty big change though, with the new driver, an FC8b disk, and the boot chime change. Do you want to wait until you have your PCB and sockets setup so you don't need to unsolder/resolder?
No let’s keep going - this is fun.
OK here we go. Definitely would call this a prototype. The driver splash screen should appear at startup, and you can hit R or A. I think I have the logic changed to point to the hidden boot sound. But we will see
OK here we go. Definitely would call this a prototype. The driver splash screen should appear at startup, and you can hit R or A. I think I have the logic changed to point to the hidden boot sound. But we will see
So I can see three ROM images in the archive. What's the difference between the ones ending FC8_ and FC8b?
Just wondering which one to try first.
This is a compression algorithm for the 68K architecture designed by Steve Chamberlin (BMOW). FC8_ is whole disk mode, whereas FC8b is cached by blocks. I tend to prefer FC8b as it requires less RAM. (FYI I think we can go even bigger than a 3MB disk with FC8, but this is just a start for now)
FC8 – Faster 68K Decompression | Big Mess o' Wires
To rule out any FC8 issues, you could try the one labeled DISK first and coming in at 4096KB exactly. That has an uncompressed 2MB disk with System 7.1.2 and the System Enabler.
Yep, I know about FC8 from tinkering with my BMOW Rominator II. I didn't know about whole disk mode vs. block caching mode - this must be the Boot-Time vs. On-The-Fly decompression mentioned on Steve Chambelain's page you linked to.
BTW, both of the FC8 images are about 3.2MB in size - is that right? I guess you didn't fill up the romdisk partition completely and the sizing is dynamic.
Sounds good.
Exactly. I thought about filling the files with 0xFF or 0x00 until they each reached 2048KB. But my EEPROM programmer essentially does this for me on the fly. Each of those FC8 has a 3MB disk, but in compressed mode they each go down to under 2MB.
I created a small app in Automator that lets you drag and drop a complete ROM image over it, and it outputs high and low split binaries. It's attached. You'll need to have srecord installed through either Homebrew or Macports, and you'll need to right click the app and select 'open' rather than double clicking it the first time you run it (because its unsigned and Gatekeeper will flag it as suspect).
I desoldered the ROMs on my test CPU card ready to try one of your new iterations... and realised I left my contact cleaner spray at my parents' yesterday. I was working on their car's ECU harness. So the next test will have to wait a couple of days. The spray is basically essential to get the SOP-44 ZIF socket on my T48 to make good contact with all the pins.
I desoldered the ROMs on my test CPU card ready to try one of your new iterations... and realised I left my contact cleaner spray at my parents' yesterday. I was working on their car's ECU harness. So the next test will have to wait a couple of days. The spray is basically essential to get the SOP-44 ZIF socket on my T48 to make good contact with all the pins.
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I got my chips burned with the new (non-compressed) ROM today and booted up.
- The chime is the same as ever unfortunately
- The Caymac splash screen comes up and you can press R or A as you say. The loading bar is a bit flickery/glitchy, is that normally how it looks?
- It boots into System 7.1.2. fine
- The ROM disk is showing up on the desktop when booted off a hard drive, it should probably be hidden. Is that easy to do?
I noticed the memory control panel under 7.1.2 lets you change to 24-bit mode which I didn't think was possible with the 500 series. The change doesn't seem to stick – maybe it doesn't really work.
Next on my list is to try one of your FC8 ROMs. I also need to try this in a proper PowerBook to verify the backlight is staying on.
- The chime is the same as ever unfortunately
- The Caymac splash screen comes up and you can press R or A as you say. The loading bar is a bit flickery/glitchy, is that normally how it looks?
- It boots into System 7.1.2. fine
- The ROM disk is showing up on the desktop when booted off a hard drive, it should probably be hidden. Is that easy to do?
I noticed the memory control panel under 7.1.2 lets you change to 24-bit mode which I didn't think was possible with the 500 series. The change doesn't seem to stick – maybe it doesn't really work.
Next on my list is to try one of your FC8 ROMs. I also need to try this in a proper PowerBook to verify the backlight is staying on.
OK darn, back to the drawing board on this one.
Yes I think I can clean up that loading bar to make it smoother. I originally designed that on a slower machine.
Good to hear!
Yes we may need to really look at the contents of the System folder. Probably need to clean up the control panels to make it more specific for the PB5XX series.
