I posted the following historical/technical information about the SuperMac Enhance memory upgrade for the Mac 512Ke on 68kmla.org and am also posting it here to ensure that it survives in more than one location. Also, @JDW did some of the original sleuthing to find an answer. So, here it is, with some edits.
The Enhance board was a great upgrade product for the Macintosh 512Ke computer with the exception that the Killy/Chabin Clip that hooked to the Mac's 68000 had frequent failures. The later Chabin clip was a little better, but still had issues. The Enhance shipped with a special plastic tool for installing the clip. It was a plastic frame that folded over and hooked on to both long edges of the clip so that it could be evenly flexed into place. But, in practical terms, the clip had a very low insertion count and tended to fail when it was over-flexed at installation (or maybe when someone sneezed), resulting in poor spring force contact with the processor pins.
(The clips might still be findable on AliExpress - I would have to check the part number.)
With Enhance, if you happened to get a working clip and did a proper install (minimal flexing and install attempts) great! You might never have a problem. However, the only reliable way to connect the clip to the 68K was to solder it to the pins (and that solution remains true today in a retro context). In the '80s and '90s, some people needed multiple replacement clips (which may have been because of over-flexing the clip on initial install -- hard to say). After SuperMac was acquired by Radius, if you called in with an Enhance clip problem, you just returned your old Machine/Enhance and they sent you a MacPlus for free! The users loved that solution (even though it was technically slower than an 512Ke wiith an Enhance board).
Anyway, as above, by default, Enhance adds 1.5Mb of RAM (6 x 256K SIMMs -- for a total of 2Mb) and a SCSI port to the Mac 512. It also has an on-board 68000 that let it run about 30% faster than a MacPlus. The reason for the speed-up was that the main motherboard 68000 CPU could manage the screen buffer while the Enhance 68000 managed application accesses to its expansion RAM. So, a Mac512+Enhance had an advantage over a single processor MacPlus that had to alternately manage screen updates and other RAM accesses. Also, I will have to check, but I think the Enhance 68000 runs at 12Mhz vs. 8Mhz on the Mac 512Ke.
Upgrading the Enhance:
Enhance could also use 1MB SIMMs for a total of 4Mb on board (plus the 512K on the Mac). However, in order for this expanded config to work, the board had to be a Rev 3 board and needed a PAL upgrade. The PAL upgrade part number was E6000 (E4000 was installed with 1.5Mb on board). So, if you find a Rev 3 Enhance board that has an E6000 PAL installed, that is a great find! It means that it can be upgraded to the max config. If it has an E4000 PAL, then it is stuck at the lower 1.5Mb RAM config. See the picture below.
Also, with a Rev 3, E6000 board, the 4 1Mb SIMMs had to be installed in sockets 1, 2, 4 and 5 (dark sockets indicated below), skipping sockets 3 and 6.
When users wanted to upgrade beyond 1.5Mb and had an old rev board, SuperMac would exchange the board for Rev 3 with an E6000 PAL installed. Otherwise, if they had a Rev 3 board with an E4000 PAL, SuperMac would simply send out a replacement E6000 PAL.
The original SuperMac part number for Enhance was STD 4110.
The power consumption, including the Mac motherboard was 6.25W. (1.25A @ 5V)
SCSI Compatibility: should work fine with contemporary SCSI devices. The interface chip is an NCR 5380. The SCSI port and attachment cable fed through the battery port on the back of the Mac512K
The Chabin Clip was part #930059-I (or 6-931645-004)
The Enhance board shipped with a modified power cable in order to connect the fan and main board power
The Enhance board came with a fan. If you find/use one of these Enhance boards, make sure you install it with a fan. It may get warm/hot. There are many newer/better options today. You could also put a fan on the upper air vents of the Mac. There are many options. The fan went in the upper air vent of the Mac 512. I also used to advise users to tape over the underside of the vent on the opposite side to ensure better cooling/draw across the entire case.
Basic Troubleshooting:
1. If you see black bars, that is a classic indication of Killy/Chabin Clip failure -- not making good processor contact.
2. If you see a Happy Mac on a black screen, that is because you have the wrong RAM config for the installed PAL. Use E4000 for 1.5Mb on board and E6000 for 4Mb on board (slots 1,2,4,5).
3. If you have software compatibility issues with software that relies on the explicit CPU timing of the Mac 512Ke, there could be issues because of the fact that the Enhance board makes the Mac run faster than expected (by about 30%, as above) --and also runs at 12Mhz (I think -- will check when I find my board).
4. If the Mac bombs at startup, it is because you have the old 64K ROMs. The Enhance board requires a Mac 512 with either the 1st or 2nd version of the 128K ROMs. It did not work with the original 64K ROMs. To see the ROM version, hit the interrupt switch or enter Macsbug and type "DM 400000". Then, look for $EExx (128K v1) or $EAxx (128K v2) in the 3rd column of the top row of the hex dump. It used to crash on the original 64K ROMs (a not-so-subtle clue) and required a motherboard swap to a newer version in order to use the Enhance. For best SCSI performance/behavior on the Mac 512ke, the 128K v2 ROMs were required.
I hope this info is helpful to someone...but here it is for posterity. You never know -- an Enhance board could fall out of outer space tomorrow and land on my head at terminal velocity, which, I suppose, would still be 30% faster than a Mac Plus
. But now, thanks to the miracle of the Internet, this technical info is safe from falling objects or other hazards. And, you now know as much as a SuperMac dealer did in 1988...and maybe even more!
The Enhance board was a great upgrade product for the Macintosh 512Ke computer with the exception that the Killy/Chabin Clip that hooked to the Mac's 68000 had frequent failures. The later Chabin clip was a little better, but still had issues. The Enhance shipped with a special plastic tool for installing the clip. It was a plastic frame that folded over and hooked on to both long edges of the clip so that it could be evenly flexed into place. But, in practical terms, the clip had a very low insertion count and tended to fail when it was over-flexed at installation (or maybe when someone sneezed), resulting in poor spring force contact with the processor pins.
(The clips might still be findable on AliExpress - I would have to check the part number.)
With Enhance, if you happened to get a working clip and did a proper install (minimal flexing and install attempts) great! You might never have a problem. However, the only reliable way to connect the clip to the 68K was to solder it to the pins (and that solution remains true today in a retro context). In the '80s and '90s, some people needed multiple replacement clips (which may have been because of over-flexing the clip on initial install -- hard to say). After SuperMac was acquired by Radius, if you called in with an Enhance clip problem, you just returned your old Machine/Enhance and they sent you a MacPlus for free! The users loved that solution (even though it was technically slower than an 512Ke wiith an Enhance board).
Anyway, as above, by default, Enhance adds 1.5Mb of RAM (6 x 256K SIMMs -- for a total of 2Mb) and a SCSI port to the Mac 512. It also has an on-board 68000 that let it run about 30% faster than a MacPlus. The reason for the speed-up was that the main motherboard 68000 CPU could manage the screen buffer while the Enhance 68000 managed application accesses to its expansion RAM. So, a Mac512+Enhance had an advantage over a single processor MacPlus that had to alternately manage screen updates and other RAM accesses. Also, I will have to check, but I think the Enhance 68000 runs at 12Mhz vs. 8Mhz on the Mac 512Ke.
Upgrading the Enhance:
Enhance could also use 1MB SIMMs for a total of 4Mb on board (plus the 512K on the Mac). However, in order for this expanded config to work, the board had to be a Rev 3 board and needed a PAL upgrade. The PAL upgrade part number was E6000 (E4000 was installed with 1.5Mb on board). So, if you find a Rev 3 Enhance board that has an E6000 PAL installed, that is a great find! It means that it can be upgraded to the max config. If it has an E4000 PAL, then it is stuck at the lower 1.5Mb RAM config. See the picture below.
Also, with a Rev 3, E6000 board, the 4 1Mb SIMMs had to be installed in sockets 1, 2, 4 and 5 (dark sockets indicated below), skipping sockets 3 and 6.
When users wanted to upgrade beyond 1.5Mb and had an old rev board, SuperMac would exchange the board for Rev 3 with an E6000 PAL installed. Otherwise, if they had a Rev 3 board with an E4000 PAL, SuperMac would simply send out a replacement E6000 PAL.
The original SuperMac part number for Enhance was STD 4110.
The power consumption, including the Mac motherboard was 6.25W. (1.25A @ 5V)
SCSI Compatibility: should work fine with contemporary SCSI devices. The interface chip is an NCR 5380. The SCSI port and attachment cable fed through the battery port on the back of the Mac512K
The Chabin Clip was part #930059-I (or 6-931645-004)
The Enhance board shipped with a modified power cable in order to connect the fan and main board power
The Enhance board came with a fan. If you find/use one of these Enhance boards, make sure you install it with a fan. It may get warm/hot. There are many newer/better options today. You could also put a fan on the upper air vents of the Mac. There are many options. The fan went in the upper air vent of the Mac 512. I also used to advise users to tape over the underside of the vent on the opposite side to ensure better cooling/draw across the entire case.
Basic Troubleshooting:
1. If you see black bars, that is a classic indication of Killy/Chabin Clip failure -- not making good processor contact.
2. If you see a Happy Mac on a black screen, that is because you have the wrong RAM config for the installed PAL. Use E4000 for 1.5Mb on board and E6000 for 4Mb on board (slots 1,2,4,5).
3. If you have software compatibility issues with software that relies on the explicit CPU timing of the Mac 512Ke, there could be issues because of the fact that the Enhance board makes the Mac run faster than expected (by about 30%, as above) --and also runs at 12Mhz (I think -- will check when I find my board).
4. If the Mac bombs at startup, it is because you have the old 64K ROMs. The Enhance board requires a Mac 512 with either the 1st or 2nd version of the 128K ROMs. It did not work with the original 64K ROMs. To see the ROM version, hit the interrupt switch or enter Macsbug and type "DM 400000". Then, look for $EExx (128K v1) or $EAxx (128K v2) in the 3rd column of the top row of the hex dump. It used to crash on the original 64K ROMs (a not-so-subtle clue) and required a motherboard swap to a newer version in order to use the Enhance. For best SCSI performance/behavior on the Mac 512ke, the 128K v2 ROMs were required.
I hope this info is helpful to someone...but here it is for posterity. You never know -- an Enhance board could fall out of outer space tomorrow and land on my head at terminal velocity, which, I suppose, would still be 30% faster than a Mac Plus
. But now, thanks to the miracle of the Internet, this technical info is safe from falling objects or other hazards. And, you now know as much as a SuperMac dealer did in 1988...and maybe even more!
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