grx1042@uoft02.utoledo.edu (Steve Snodgrass) (07/12/90)
This is a review of the BaseBoard 4 Meg RAM expansion for the A500, by Expansion Systems. I'm in no way connected with the company, blah, blah. Well, I recently bought a BaseBoard 4 Meg RAM board for my A500, with 2 Megs installed. Here's the lowdown: DESIGN: This board is completely internal and uses 256K x 4 120 ns DRAMs. Faster chips will work, of course, but cost more. It occupies the A501 connector, so you cannot use it in tandem with a 501. It's expandable to 4 Megs, giving you a total of 4.5 Megs. INSTALLATION: Not recommended for the faint of heart, but it's really not that difficult. Of course, I'm the adventurous hardware-hacker type. The expansion actually consists of two separate boards - the main RAM board, that plugs into the A501 connector, and a daughterboard that plugs into the socket of the GARY chip and the main RAM board. This means you must remove the GARY chip, plug in the daughterboard, and plug the GARY chip back into the daughterboard. Also, on Rev. 5 motherboards, you either have to ditch the metal RF shield, or just bend or cut off a little part of it. I just cut off the piece, it's not that big. RAM can be added in blocks of 512K (4 chips). COMPATIBILITY: The BaseBoard will work with 1.2 or 1.3 ROMs. However, it says that if you're using 1.2 the board must contain at least 2 Megs. No problem for me, I have 2 Megs on it. The board will work with a Rev. 5 or 6A motherboard, you can check your version by opening up the 500 and looking inside. Apparently, the GARY daughterboard is a different size for these 2 motherboards so be careful if you order one. I didn't know about this but the standard seems to be Rev. 5 so I was OK. The BaseBoard will also work if you have a Fatter Agnus chip, with the quick switch of a few jumpers, giving you a 1 Meg of chip RAM. You might, however, have to reconnect a trace that gets cut on Rev. 5 mb's if your Fat Agnes is already installed. AUTOCONFIG: This differs depending on your setup. For those with the old Fat Agnes, 1.75 Megs of the board will autoconfig, anything more than that can be added with a program that comes with the board called CRam. For me, that means I boot with 2.25 Megs and CRam adds the last 256K. This is no problem - stick CRam in the startup-sequence where needed and forget about it. If you're using a Fatter Agnes, nothing autoconfigs except the 512K of extra chip RAM, so you boot with 1 Meg chip and CRam adds the rest. Also, fast RAM is chopped into 512K blocks for some reason. This won't be a problem unless you need to run a program which for some weird reason requires a huge segment of contiguous RAM. However, Expansion Systems is also offering a special version of the Fatter Agnes that will allow autoconfig of 2 Megs (512K chip, 1.5 Meg fast) and offers contiguous RAM. Fast RAM is contiguous using the old Fat Agnes. SATISFACTION: I'm very happy with my BaseBoard. It offers great internal RAM expansion capabilities for the A500 at a VERY reasonable price, especially since RAM chips are cheap again (I'm only paying $60 per Meg for 256K x 4 120 ns DRAMs). I don't know how much the board lists for but I got mine for about $120 mail order from Abel's Supply. It was preconfigured to 2 Megs, so you don't have to bother plugging in the chips. So for only $240 you can have a 2.5 Meg A500. FINAL NOTE: Forgot to mention that it DOES have an A501 compatible clock, so no worries there. Same old SetClock command will work. Steve Snodgrass - Ph'ran |SUBTEC - Student Union Board Technical Services| Green Rider of Telgar Weyr|Turbosound - the only way to fly. TMS-4 | --------------------------|-----------------------------------------------| GRX1042@uoft02.utoledo.edu|"It had limited capability, with a mere hundred| GRX1042@uoft02.BITNET | thousand gigabytes of RAM" -Jack L. Chalker | "Who explains the dreams we know/Carry us through from day to day" -me