I have the same controller on my A500+, and second the SCSI card reader from Mechware. I also have an external CD-RW connected to mine. It works great. If I am not mistaken, the A500 HD+8 uses the 30 pin simms. I have 8 meg in mine, which is the max, using 4 2 meg simms. I have several 1 meg simms, however, with the 1 meg simms, you can only have 4 meg, as there are only 4 simm slots. The 1 meg simms are pretty common. I bought the ones I have on ebay, they were 4 1meg simms for like $13, so not bad. The 2 meg ones would give you more ram, but are not as common, at least not as I have seen on ebay. Also, If I am not mistaken, the A500+ only has 1 meg of chip ram. Mine has 1 meg, and with the trapdoor 512K module plugged in, has 1.5 meg of chip ram. At least that is how mine is set up.