BFEXTU's "Super" Mac II Revival

BFEXTU

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Jul 15, 2022
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I have been working on my Mac II and it is now up-and-running!

Initial Treatment:
- Thorough cleaning
- Removed the old (non-leaking) Varta batteries
- Installed new battery sockets
- Installed 4Mb
- Put in a SuperMac Spectrum/8 Series III 8-bit video card

Remaining Items:
- Still working on the dual floppies -- need some replacement gears for the rebuild
- Plan to add a built-in BlueSCSI for auto-boot
- I may add an upgraded ROM SIMM at some point so that it is 32-bit clean - it would be nice to have an 8Mb ROM boot disk
- Upgrade to 68882 - I think the Mac II automatically supported this upgrade

During testing and triage, I was jump-starting it with one of the batteries on the white power lead. But, I needed to install the batteries, because the Spectrum/8 III has Round-Robin video configuration on startup for multiple configs. It saves its setup in the slot PRAM. So, without battery backup, it just keeps resetting at startup, of course.

Anyway, it now boots and works very well! I had some initial issues with video, but I needed to change the monitor and cable - it wouldn't sync up or was just too slow. So, I am currently testing it on a 640x480 Apple Monitor (that still seems to work very well) and I can see that it is cycling through all of its configs. It includes 4 onboard oscillators for different video configs and an optional slot for 1 more (usually to support NTSC or PAL).

Spectrum/8 Series III v1.2 supports the following video configurations:
Standard Configs:

19" 1024x768 60Hz -- uses onboard 64Mhz oscillator
19" 1024x768 75Hz -- uses onboard 80Mhz oscillator
16" 832x624 -- uses onboard 55Mhz oscillator
13" 640x480 -- uses onboard 30.24Mhz oscillator

Optional Configs:
15" Portrait 640x870 -- uses optional 57.28 Mhz oscillator
NTSC 640x480 (interlaced) - uses optional 14.32 (14.31818) Mhz oscillator*
PAL 768x576 (interlaced) -- uses optional 17.73 Mhz oscillator*
*NTSC and PAL modes are not perfect "broadcast" standard, but they were good enough for general consumer use, such as showing output on a TV screen or connecting to video recording devices that expected NTSC and PAL signals.

The board also has many other cool features -- virtual desktops, pan and zoom, etc.

There is also some additional space on the board for additional PALs - not sure what those are for. Hmm...

In order to control the board, explicitly set a particular video configuration, and use special features, as noted above, you need to have the SuperVideo cdev installed in the System Folder so that it can run at startup. Otherwise, for general video selection, the slot PRAM had to be clear and users had to use Round Robin. (see below)

Also, I think there is a new ROM -- maybe version 1.3 that includes support for 17" (and maybe 12") monitors, but I don't have it. If anyone has a Spectrum/8 Series III v1.3 ROM image, let me know!


MacIIRevival.jpg


Below is a video of the Round Robin startup configuration for this card that runs whenever the NuBus slot PRAM doesn't have a saved video config. For historical purposes, there were 3 ways to reset the video config and cause Round Robin to run again:
1. Zap the PRAM at startup
2. Remove the card from the slot, turn the machine on and off, then reinstall the card
3. Move the card to a new slot that did not have a card installed at the previous power-on

The 4th way doesn't count!
(4. Have a machine that has a dead PRAM battery and doesn't save anything)

 

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BFEXTU

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Jul 15, 2022
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Next up...it looks like my Mac II's logic board has a fully-populated PMMU socket for a MC68851 Upgrade:
MMUSocket.jpg

Here is the MC68851 Pin Pattern for Comparison:
68851PinPat.jpg

Here is the pin pattern for Apple's 70-pin HMMU. If your Mac II has this pin pattern on the back side of the motherboard for the MMU socket, it can't be upgraded:
HMUSocket.jpg

I will also be replacing the MC68881RC16A with an MC68882RC16A and burning new FDHD ROMs for it using the XGecu T48. Hmm...I may have to get a ROM Eraser. I hope the 27C512's arrive blank -- they should. I only have to erase them if I screw up. :D
 
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retr01

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Wow! I just learned something new. The Mac II uses a Sony CR45 PSU. :) Is that a cousin of the Sony CR44 in the SE and SE/30?

Hmm, I want a Sony PSU for my IIci. I wonder if Sony did better than GE for the PSU in the IIci. Of course, I understand there is no Sony PSU for the IIcx, IIci, etc., right?
 

BFEXTU

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No idea. I never cared too much about Apple's power supply choices and they never really failed for me...ever.
 
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BFEXTU

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On this machine, my 68851 PMMU test was successful. With an MC68851RC16A installed and using the video card in slot $9, I am able to allocate 13Mb of VM and it seems to work great.
 

BFEXTU

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Well...I have added a 68882 to the Mac II, but it doesn't seem to improve performance very much. Have any of your benchmarked your Mac IIs with an '881 vs '882?

MacII68881Bench.jpg


MacII68882Bench.jpg
 
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BFEXTU

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I thought the internal pipelining was supposed to be much faster...but also, I didn't include the FPU-specific tests, which was kind of derpy of me. So, I am going to re-run it and test everything. ^_^
 

BFEXTU

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Regarding PMMUs, I should be receiving more 68851s for testing. So, the Mac II will get a permanent upgrade of its very own.
 

lilliputian

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I was able to get a PMMU for my Mac II for not too much. I don't know about speed increases, but I know it enables more RAM to be available. I believe it's also required for Virtual Memory (not that I plan on using it for that).
 
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BFEXTU

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From full testing, it looks like the MC68882RC16A increases FPU performance by about 25-30% vs. the MC68881RC16A in the Mac II. The numbers vary slightly on multiple test runs, but are more or less consistent. I forgot to show the CPU banner on the '881 run, but not worth doing over. The main things I wanted to see were the FPU results.


Mac II with MC68881 FPU:
(
System 7.1, Extensions Disabled, SpeedTest 3.0.5, Spectrum/8 Series III 640x480)
MacII881BenchFull.jpg



Mac II with MC68882 FPU:
(System 7.1, Extensions Disabled, SpeedTest 3.0.5, Spectrum/8 Series III 640x480)

MacII68882BenchFull.jpg
 
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lilliputian

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Wow! I just learned something new. The Mac II uses a Sony CR45 PSU. :) Is that a cousin of the Sony CR44 in the SE and SE/30?

Hmm, I want a Sony PSU for my IIci. I wonder if Sony did better than GE for the PSU in the IIci. Of course, I understand there is no Sony PSU for the IIcx, IIci, etc., right?
The Mac II/IIx and IIfx can have either a Sony or an Astec PSU. The IIfx PSU is "thermostatically" controlled so that the fan speed varies with temperature, whereas the II & IIx's PSU goes full blast at all times. Otherwise, they are identical I believe.
 
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BFEXTU

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Yeah - the Mac II fan is a nice baby bus engine. The FPU upgrade seems worth it @ min 25% performance gain. I will also be adding an MMU to that machine and upgrading the ROMs, as above. Some day, it may also get a 1.44mb drive if I can find the SWIM for it.
 
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retr01

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The Mac II/IIx and IIfx can have either a Sony or an Astec PSU. The IIfx PSU is "thermostatically" controlled so that the fan speed varies with temperature, whereas the II & IIx's PSU goes full blast at all times. Otherwise, they are identical I believe.

So, three wired fan for the IIfx? The GE PSU in my IIci only has two wires for the fan, meaning the IIci and IIcx do not have thermostatical control and have full blast like the II/IIx (and SE30 lol) PSUs?