qarl@wucs1.wustl.edu (Karl Stiefvater) (10/08/90)
Hi. I posted this once before, and received no response. :(. Anyone have any ideas? Montgomery Grant strikes again. A friend of mine ordered his new Agnus chip through them, after being assured that he would receive full instructions on how to install it... Guess what. So, if anyone on the net has any idea what jumpers to jump, or traces to cut, or anything at all, we'd greatly appreciate the help. Thanks much in advance, Anonther victim of Mongomery Grant.
jeremym@brahms.udel.edu (Jeremy A Moskowitz) (10/08/90)
In article <1990Oct7.183737.9058@cec1.wustl.edu> qarl@wucs1.wustl.edu (Karl Stiefvater) writes: >Hi. I posted this once before, and received no response. :(. Anyone >have any ideas? > > Montgomery Grant strikes again. A friend of mine ordered his new Agnus > chip through them, after being assured that he would receive full > instructions on how to install it... Guess what. > > So, if anyone on the net has any idea what jumpers to jump, or traces to > cut, or anything at all, we'd greatly appreciate the help. > > >Thanks much in advance, >Anonther victim of Mongomery Grant. Unbelievable! The file finder on my hard drive worked! And ... I found this file! <disclaimer: just because it's on my hard drive, doesn't mean squat!> The new Fatter Agnus chip from CBM is an exciting upgrade to our already amazing Amigas. The chip allows owners of Amiga 500s or 2000s to use one megabyte of memory for chip ram, instead of the previous limit of 512K. The new machines are shipping with the Fatter Agnus installed, but the chip is available for retrofitting existing machines. I use my 500 mostly for desktop video. When I heard about the new Fatter Agnus, I immediately order it. When it arrived, I opened my Amiga and installed the new chip. When I powered up the machine, much to my dismay nothing had changed! The chip had not come with any instructions, and I could find nothing on the bulliten boards. Also, there are no Amiga dealers within 150 miles. I finally got the info from W. Howe online. Here is the method for putting the Fatter Agnus into an Amiga 500. WARNING: This is not a mod for the faint of heart or technically untrained!!! Opening the Amiga will void your warranty, and the mod described below could kill your computer if not properly done! This mod requires chip-level soldering. If you are not comfortable with this -- get someone to do it who is. A dealer is still your best bet, although a good electronics repair shop could do it. Now that that's out of the way, here goes. You need the following More [Y,n]? to do this mod: Amiga 500 with 512K expansion installed (add'l external fast RAM suggested as well) Kickstart 1.3 Rom Fatter Agnus Chip (p/n 318069-02 , a.k.a. 8372A) Grounded, low-wattage soldering iron Ass't tools, light-gauge wire, etc. (A chip-puller is helpful, and can be rented or bought from Safe Harbor.) Still here? O.K. First, open the Amiga, remove the keyboard and the RF shield. You should be looking at a nicely laid-out circuit board. Before you touch anything, be sure you ground any static out of your body by touching a pipe or lamp or use a ground strap. The components you are dealing with are VERY sensitive to static, and can literally be destroyed with a touch. If you haven't already installed the Kickstart 1.3 ROM, this is the time to do it. Look at the 1.3 ROM in you hand, and locate the old ROM toward the left side of the motherboard. The ROM is labeled on the motherboard, and its p/n is very similar to the new one. Carefully pull the old ROM out of its socket, and gently insert the 1.3 ROM in its place. More [Y,n]? Be sure that the notch on one end of the chip is at the end of the socket that has the notch. The chip should seat evenly and easily. Check to make sure none of the pins got bent. Now, locate the old Fat Agnus chip. It is near the center and looks just like the Fatter Agnus. It too is labeled on the motherboard. The trick here is to pull the old chip without damaging the socket. If you have a chip puller, locate the slits on either corner of the socket and put the prongs of the puller in them. Use a gentle rocking motion to loosen the chip and remove it from the socket. If you do not have a chip puller, find a small, flat-blade jewelers screwdriver. Using the slits in the socket, gently pry first one side, then the other until the chip comes loose. Be very careful with this socket -- having it replaced will cost big $$$!!! Next, look for a dot in the center of one side of the socket. This dot will line up with the dot on the side of the Fatter Agnus. Align these dots, and gently press the new Agnus into place. It, too, should seat evenly and easily. Now the fun starts. You need to make two small modifications to the motherboard. First, locate the 68000 chip near the left edge of the board. Just to the right of this chip are three solder pads More [Y,n]? marked JP2. The two bottom pads are connected together. With a sharp knife, carefully cut the trace between the bottom two pads. Be sure not to cut any other traces. You now need to connect the top two pads together. You should be able to put a "blob" of solder between them. The final modification is made to the Gary chip. Pin 32 of the chip controls the 512k internal RAM expansion. This pin must be disconnected from the EXRAM line and tied to +5 volts. The easiest way to do this is to remove the Gary chip from the socket. With the notch at the left end of the chip, the lower left pin is pin #1. Going counter-clockwise around the chip count up to pin 32. When you are certain you have found pin 32, gently bend it straight out from the chip with a pliers. Line up the notch with the socket and gently insert the chip. Pin 32 should be sticking out from the side of the chip. Locate a source of +5 volts on the board. I used the three small solder pads located on the motherboard just to the left of pin 32 of the Gary chip. The schematics in your manual can help you. I used a piece of 30 gauge Kynar wire-wrap wire to connect pin 32 to the solder pads. Any similar wire will work. Solder one end of the wire to the solder pads using as little heat as possible. Work quickly. More [Y,n]? Connect the other end of the wire to pin 32, and solder. Again, use as little heat as possible. Now you can put the RF shield, keyboard and cover back together. If you have been using FastMemFirst in your startup sequence, you should delete it. Be sure to use "SetPatch r" if you are using RAD:. When you boot the machine, type "Avail" from the CLI. There is the result of your time and money -- one megabyte of chip RAM!!! Congrats! Chris J. Prudhomme, Duluth, MN, USA Plink = Vid-chris Genie = C.Prudhomme CServ = 75756,2670 Again, what you do hacking up you 'Amy... is your business.. you asked for help, my son, and you hath received! IN ABUNDANCE! Now! If someone wants to give me a hack to get PAL/NTSC hardwire switch for the 500/2000 I would be a most happy camper! jeremym@brahms.udel.edu -Come and take a ride on the Scheme train...