Tom and Lisa's Weird Web Page
DOS Card Madness !
Apple's DOS cards are really kind of geeky-neat. Ranging from 486 DX/25 to P166 CPUs these cards allowed a complete integration between the Mac side and the PC side. Orange PC also puts out some faster cards ($$$).
Before I go further I should point out that Apples drivers are not 32
bit compliant. 32 bit drivers can be bought from
I have 2 DOS cards, a 486 DX2/66 and a P-100 card I recently bought on
Ebay for about $35, including the cables.
Replacing the CPU in a DX2/66 card: I was wondering if it was possible to upgrade the CPU on this card and after some research its turns out several people have tried this (for example: www.ph.utexas.edu/~tai/586upgrade.html). You need to find a 5V CPU or a CPU with a voltage regulator. I found a Cyrix 5x86-100GP processor and regulator on Ebay for about $15 total (The 100 GP is common, the 133 GP is a little harder to find)
The CPU in the DX2/66 card is a PGA and can be removed using an extraction tool or a dull knife if you are brave. Be careful not to bend any pins or stress the CPU itself. Go slow.
After removing the CPU this is the card and the Cyrix CPU on the left and the old DX2/66 CPU on the right (for this pic I took off the SoundBlaster sound module):
A picture of the Cyrix CPU alone.
You notice the small white dot near the Cyrix logo ? This indicates the unique corner on the CPU. All CPUs must be inserted in the socket in one particular direction.
To put the new CPU in, just gently push it in the empty socket, making sure the CPU is oriented correctly. Also make sure all of the pins are going in.
After putting the CPU in (the metal item up top is the CPU removal tool, it works on both 486 and 68040 PGA chips):
Now that the CPU is in, time to test it out ! I am testing the CPU in a Centris 650:
Notice how the card doesn't reach all the way back to the port opening ? Occasionally I see DOS cards for sale that have extenders so the video port pokes out of the back of the computer. I need to find one or make one.
Fire up the computer and:
It works ! As soon as I get my parts in for another project ("44
Special") I will go through and load W95 onto it. For some reason, no
matter if I use any of 3 different CPUs or 3 different card, or 3
different computers, the machine always boots with 3 beeps. Is this
Pentium 100 DOS Card Fun: I got one of these pretty cheap, and it works ok. You can even run some old games on this without much trouble.
#1 is the CPU
Notice the 2 sockets (#5)? Those are for adding more VRAM (the card starts with 512 K of VRAM and you can upgrade it to 1 meg total). The VRAM modules can be bought from www.jameco.com, part #148435 (you need 2).
Now take a look at the ribbon cable.
The ribbon cable is designed to go from the card to the DAV slot on some macs (7200/7500/PowerCenter/PowerCurve). Using this connector allows you to not have to use the external video adapter.
The video cable is used if you don't have or cant use the DAV cable:
The CPU is soldered on, and I don't think there is an easy way to upgrade it (supposedly the speed of the CPU is set to 3x PCI bus speed).
I am also looking for a way to get the card in my B&W G3, but the audio
cables don't match up (that and I need another video adapter).
Installing Windows 95 on the DOS card:
Once you have the card installed, install the PC setup software from apple
(version 1.6.4 is the latest). Once done, start the PC Setup control
panel and select or make a drive container for the PC. Now boot the
PC, and switch over. Start loading DOS and/or Windows exactly as you
would a real PC. That's all you have to do.
Adding a Socketed CPU to an Apple DOS card: If you are prepared to do a bit of work, it is possible to remove the CPU from an Apple DOS card (either the P100 or P166 card, and it probably works for the Cyrix 166 version, too). Removing the CPU is the hard part. The CPU is mounted in a pins-through type, and has some ~300 pins. Here is a pic of the top of the CPU, after removing the heatsink:
- hacking the CPU off
Hacking the CPU off is incredibly tough. The ceramic casing requires a diamond dremel bit to cut through. Forget normal steel bits. In my second attempt to remove a CPU (more on that later) I hacked off about 1/4 of the CPU, but it took me 2 hours or so and is dangerous in that it is easy to damage the card.
Chip Quik (http://www.chipquik.com/) is a bismuth based alloy that you melt into each pin on the back, and this lowers the melting point of the resulting alloy so you can use a heat gun to melt all the solder at once. You can get Chip Quik at Digikey. I think, from my experiences, you must use Chip Quik.
A Pace station is a combo soldering iron and vacuum pump. This is very handy. I could get all the pins clean using a Pace station, but it is very useful in the cleanup.
First Attempt: My first attempt was on a P100 card that I got for a mere $10. At first, I tried a Pace station to remove all the solder, but there were a number of pins I couldn't get clean. I then decided to Chip Quik every pin. After doing this, I used a heat gun to heat all of the pins, and use a flat head screwdriver to slowly pry the CPU out while the solder was molten (be gentle). After removing the CPU, this is a pic of the front:
After using the Chip Quik there is a lot of alloy you need to clean up and the Pace station is perfect for this. After cleaning up, it was time for the next step.
I ordered several Socket-7 CPU sockets from Digikey (part #916657-1-ND); these cost a few bucks each. Making sure that I had the socket oriented properly (there is only one way to fit the socket in), I gently tried to insert the socket. However, the socket has one extra pin that there is no hole for. The extra pin is on the inside row and you have to snip it off. Before soldering the unit on, make sure _all_ the pins are through the holes and sticking out of the backside. Then, solder away. After finishing the socket, here is a pic of the top :
and the back of the card:
Not too shabby of a job for the first try.
Second Try: My second attempt is with a P166 card. I
decided to remove all the solder I could with a Pace station and Chip Quik
the rest of the pins. I would then use the Pace station on the "quiked"
pins which should allow me to complete the job faster.
OK. I sawed off about 1/4 of the CPU and it took me about 1-2 hours. Damn, that CPU casing is TOUGH ! Considering the damage I could of done, I do NOT recommend using a Dremel. Instead, I Chip Quiked all the pins, and using a heat gun, managed to get the rest of the CPU out. From now on, I will use Chip Quik. The clean up still required a bit of work with some solder wick and a pace station. After clean up, I added the socket (once again making sure to clip the one superfluous pin, and making DAMN SURE all the pins went through).
Boot up was successful, so once again... SCOOOOORRRRRRREEEEE !
Putting the socket in is half the work. You cant just stick any
old Socket-7 CPU into the socket and get it to work. First of all,
different CPUs require different voltages. The P100 and P166 cards
are set to deliver 3.5 V to the CPU and this could fry newer CPUs.
While you could try to re wire and change both of these settings, there is an easier way. Powerleap (www.powerleap.com) sells Socket-7 adapters that modify the incoming voltage and can change the CPU speed. The cheapest one to buy allows the use of Pentium, Pentium MMX, K6, K6-2, Winchip, and 6x86/M2 CPUs (It also works with the K5 and Pentium MMX mobile). It costs $50 and can be directly ordered from them. Here is a pic of the socket adapter with a CPU in it:
The CPU is actually powered through the 4 pin power adapter, so you can use CPUs that would otherwise draw too much power through the PCI bus.
One note: When removing a CPU from the adapter, you really should use a CPU removal tool for best results. Before putting the adapter and CPU into the socket, set the voltage and clock speed for the CPU you are using.
As of this point (8/5/01), I have tried the following CPUs:
In the Apple P-100 card:
Pentium (100, 133)
Only with the Pentium and Pentium MMX (not the mobile) does the card work perfectly. All the other CPUs disable the L2 cache on boot, except the Winchip, which does not boot After some experimentation with numerous cache enabling software, I think this is a BIOS problem. The old BIOS cant recognize most of the CPUs and disables the L2 cache for some reason. Other than that all the CPUs (except the Winchip) work fine (just slow without the L2).
Unless I can find out how to replace or modify the BIOS, I am not sure how to proceed, other than using a 233 MMx CPU (and hopefully overclocking that to 266 MHz).
In the Apple P166 card (the second try):
Pentium (100, 133)
As before, only with the Pentium and Pentium MMX (not the mobile) does the card work perfectly. All the other CPUs disable the L2 cache on boot, except the Winchip, K6 and K6-2, which do not boot at all.
The M2 CPU now leaves the L2 enabled ! I am not sure why the M2 now works in the P166 with the L2 enabled. The P100 and P166 cards Apple put out are supposed to use the same damn BIOS. This result is telling me something, but I am not sure what. As of 8/24/01, I have a 366 MHz M2 CPU on order. I am keeping my fingers crossed.