Path: qucdn!ccs-server.QueensU.CA!news-server.csri.toronto.edu! rpi!zaphod.mps.ohio-state.edu!malgudi.oar.net!ucunix.san.uc.edu!uccba!ucqais.uc.edu!ggibeau From: ggibeau@ucqais.uc.edu (AMOEBOID) Newsgroups: comp.sys.amiga.hardware Subject: Amiga 2.04 ROM in modified A1000 Keywords: AmigaDOS 2.04, Amiga 1000 Message-ID: <1991Nov20.042727.2489@ucqais.uc.edu> Date: 20 Nov 91 04:27:27 GMT Distribution: usa Organization: U.C. Dept. of Biology Here is an article (I posted it last year some time) that we had published in Amazing. With the advent of 2.04, we thought there might be some more interest in using Kickstart ROMs in your A1000. Here is a slightly modified version of the article that was published in the May, 1990 edition of Amazing Computing. With the advent of AmigaDOS 2.04 ROMs, we thought it might be of interest to folks as this is an inexpensive way to have the ability to use 2.04 ROM in your Amiga 1000. Duplication of this article without express written permission of the authors will probably result in your not winning the Publishers Clearing House sweepstakes (and you thought you were going to meet Ed himself :-)). ---------------------------------clip here-------------------------- How to turn your A1000 into a ROM based machine by Dwight Blubaugh and George Gibeau, Jr. Ohio Valley Amiga Users Group (OVAUG) WARNING - This hardware modification will VOID your warranty (GRIN). It requires some electrical component assembly experience, such as soldering and desoldering printed circuit boards. Do not try it if you do not feel comfortable disassembling your computer and working inside your machine. Please read this entire article before actually starting any of the described work. Are you tired of spending extra time looking for that misplaced Kickstart disk in order to get your A1000 up and running? Do you want to run a BBS but don't want to deal with the infamous Kickstart "hand" screen after a power outage? Would you like to get rid of the daughterboard and eliminate a potential source of GURU visits? If you answered yes to any of the above questions, then this hardware modification will be of interest to you. With a little bit of work and the following information, you can make your A1000 a ROM based machine. The first choice you have to make is to decide which version of the Amiga ROM you want to use. When deciding which ROM version to run, carefully consider whether you will be running an autoboot hard drive or not. If you are not going to run an autoboot harddrive, then you can probably go down to your friendly local dealer and talk them out of a 1.2 ROM that they acquired during an upgrade to 1.3 for a 500/2000 owner. If you will be running an autoboot hard drive, then you can buy the 1.3 ROM for about $35. [ed. 2.04 kits are about $99] You will need to gather the following tools before you begin: 25 watt soldering iron, desolderer (vacuum type - piston, not bulb - works best), thin electronic solder, small pair of wire snips, small needle nose pliers, Phillips screwdriver, flathead screwdriver,and a good volt/ohm meter. parts list QTY PART TYPE 2 74F257 2 74LS244 2 20 pin IC machine socket 1 40 pin IC machine socket 1 piece 30-22 gauge wire 1 1.2 or 1.3 ROM (or 1.4 - grin) [ed. or 2.04] 36 gold posts (use the ones removed from the motherboard). 1 16L8 PAL (CAS) 1 16L8 PAL (EN) (for engineers, we can supply JED file for these, or the PAL equations - *** The CA A1000 docs have wrong equations!! The TTL's can be obtained from any electronics supply house such as Digi-Key Corp.. PALs can be obtained from several different sources; Commodore, Spirit, or if needed, we can supply them. If possible, order 15ns PALs instead of the 25ns, as these will perform better. Disassembly of the machine. Find a large, clean work area with plenty of light and electrical outlets. Cover the work area with some sort of static-proof material to keep from damaging the parts. Unplug the power cord to your machine and disconnect all external devices from the computer (drives, monitor, mouse, etc..). Turn the computer upside down and remove the 5 Phillips screws holding the top and bottom parts of the case together (it will greatly facilitate reassembly if you organize the screws into groups based on their origin within the machine as you remove them). Carefully turn the computer back to its normal position and remove the front 256K memory cartridge (if installed) and then the entire front faceplate. Next, GENTLY separate the case halves (if you start on one side at a time, and pry the top away from the bottom, you will get better results). The case is connected by 2 small hooks on each side, be careful not to pry too hard or you will break them. Set the top of the case off to the side where it will not get in the way. Next, remove the metal RF shield which is held in place by 14 screws and 2 metal tabs (tabs can be straightened with a small pair of needle nose pliers). Remove the screws and posts securing the disk drive and remove the drive, including power and data cables. The floppy LED must be removed from the front panel or disconnected at in-line coupling, depending on the model. Disconnect the power supply cable (a screwdriver may be needed to get the plastic tab to unhinge enough) as well as the power LED. You should now have just the mother and daughter boards remaining. To remove the daughterboard, unscrew the 3 small screws holding the board down. The daughterboard is now held in place by numerous gold posts. In order to separate the daughterboard, begin on one side and gently pry up while moving around the board (do not apply too much pressure as you do not want to break the board). After removing the daughterboard, grasp the motherboard near the side where the mouse and joystick plug in, slightly pulling the side of the case away from the board, and remove it from the case. It will come away with the bottom RF shield attached. To remove this, straighten out the remaining metal tabs securing the shield to the board. Finally, remove the 3 plastic stand-offs that support the daughterboard, they are secured from the bottom of the motherboard by 3 small screws. You should now have nothing in front of you but the motherboard. Now comes the fun part :-), this will go faster if you have a friend handy, but it can be done by one person. You will need to desolder and remove ALL of the gold posts. This is best accomplished by sucking the solder from the holes first, then gently pulling on the post with the needlenose pliers from the component side while heating it up from the solder side. Try not to bend the gold posts during removal as they will be used later. Also, do not apply too much pressure so as to damage the plate though holes. There are a total of 124 gold posts to remove, so take your time, and be careful not to gouge into the board with the soldering iron or you may inadvertently cut traces. After all posts have been removed, you will need to clean the old solder from the holes. This can best be done with a vacuum type desolderer. To facilitate solder removal, fill the holes with new solder, then heat up the solder and suck it out. This works better than trying to remove the old solder by itself. A final cleaning of the area around the holes can be done with the aid of solder wick, this will help remove any splashes or flakes of solder that may cause problems. Next, carefully desolder the capacitor located at C137 and save this, it will be used later. Solder the 4 TTL chips into the following locations (machine pin sockets are optional): the 74F257's into U2I and U2J (**NOTE** the board is silk screened at these spots with the label S257, however F series chips are used on the daughterboard. The F series is a better chip than the S series), the 74LS244's into U3G and U3I. The 20 pin IC sockets go into U5L and U5M, these will be where the PALs go. Remove the 2 socketed ROMS (but leave sockets for now) located at U5N and U5P and keep these as a memento of your prehistoric machine days. Next you will have to cut 2 traces and solder 2 jumpers on the motherboard, this will vary depending on which board revision you have. If you look on the motherboard under the floppy drive you should be able to determine the board revision. It will be one of the following, either Revision 6 or Revision A. Cut the appropriate traces and add appropriate jumpers (a small piece of 30/24 gauge copper wire, bent over, makes a perfect jumper) dependant upon the motherboard revision: (for correct directions on which cuts to make, send lots of small, unmarked bills... :-), actually I will put together a IFF file of the diagram and send it up. If you do buy the board, it will come with complete directions and pictures). You are finished with the motherboard for the moment, set it aside and concentrate on the Kickstart ROM adapter board. Kickstart ROM Adapter Board The following instructions are for a printed circuit card available from us, if you wish to wire wrap one or etch your own, then it is assumed that you know what you are doing and will be able to follow the provided pin list. Refer to Figure 5 for components and locations described in the following steps. Using the gold posts previously removed from the motherboard, place them into the proper holes, extending just above the surface of the board. This works easier if you seat them from the bottom. Once in place, press down on the card (top side down) to ensure that the pins are flush with the top of the card. When you are sure all pins are even, solder them in place. Next, place the 40 pin socket in the card making sure that all pins are aligned into the proper holes, as well as proper orientation (pin 1 of socket in pin 1 hole), then solder it in place. The last item to solder is the capacitor that was removed from the motherboard (orientation of capacitor is not important). Provisions have been made on the card for a 512K ROM if CBM ever uses this part. This is accomplished by a trace cut on the adapter board and a jumper to A18 on the motherboard. This signal is NOT available on the ROM sockets in a stock A1000. [ed. I guess Hell finally froze over - it is here!! :-)] Trouble Shooting Before powering up your machine, it is a good idea to check for potential errors. One of the first items to check is the adapter board. Visually inspect it for any solder bridges (solder making a connection between two spots where it should not be) or solder flakes that may have occurred during the assembly process. If you find any, carefully scrape them away ensuring that you do not do any damage to the card in the process. Next, test the ROM chip for shorts using a volt/ohm meter. Place 1 probe on pin 1 and run the 2nd probe along the rest of the pins, then move the 1st probe to pin 2 and repeat. Continue this until all pins have been checked. The only pins that should be connected are pins 10, 11, 30, and 31 (all of them are ground). If you find any shorts, you will have to determine where the problem originates. This may take a bit of work, but if you were careful during the initial assembly this should not be necessary. Another potential source of error can be caused by heat damage causing the separation of pads and/or traces from the motherboard during the desoldering process. You will need to both visually and electronically test the circuitry. Start testing the traces as they leave the ROM sockets and make sure they are making the proper connections. The big moment :-) Your computer should now be ready to test. Temporarily replace the motherboard in the case, hook up the power supply, disk drive (can fit in loose) and the monitor. The card that you just finished assembling will fit into the existing sockets (U5N and U5P). Make sure it is oriented in the proper manner (Figure 6). Press it into place, making sure that all pins are in the proper receptacles. Making sure nothing else is loose on the motherboard, turn on the power. If all went well, you should see the familiar gray to white cycle and in a few seconds the assuring "Insert Workbench" screen [ed. or the new animated disk insertion screen if using 2.04 ROM]. If this is what you see, then congratulations are in order, you have successfully completed this project, if not, then some additional error checking has to be performed. To explain fully what additional checking has to be performed is beyond the scope of this article, but basically obtain an A1000 schematic and verify connections to all new chips. If your computer is properly functioning, turn off the power, disconnect all external devices, and remove the adapter board. Remove the motherboard from the case and unsolder the sockets at U5N and U5P and clean the holes as before. The sockets must be removed and the board soldered in place to ensure the proper fitting of the floppy disk drive. If the adapter board is too high off the motherboard, it will interfere with the floppy chassis. Insert the adapter board into the proper location (maintain proper hole alignment) and solder it in place. After you are finished soldering, trim the gold posts even with the solder. Reassembly Since you already have the computer apart, you may as well take this opportunity to clean it. For optimal results use Flux-off{tm} or alcohol to clean off the solder side of the board, if nothing else, blow the dust off all the components with a clean source of air and make sure all chips are seated securely on the motherboard. Now you are ready to reassemble your machine. Replace the RF shield on the bottom of the motherboard and secure it in place with the metal tabs that are not used to hold down the top shield (a half twist with the pliers will do the job). Next, place the motherboard back into the bottom of the plastic case and replace the 2 screws that will be under the drive. Reconnect the power supply cable, power LED, floppy drive ribbon cable, and floppy drive power cable. Re-seat the floppy drive into its appropriate place (make sure the ribbon cable does not come off the drive) and refasten the screws and posts that hold it to the motherboard. Replace the top RF shield and secure it with the screws (make sure the correct screws go back into the proper locations). Next, replace the backplate and the faceplate, be careful not to break them (the backplate can be bent, but do not overbend). After the front and back plates are in location, replace the top of the case and ensure that it latches into place, secure it with the 5 screws from the bottom. After replacing the front memory module (if present) as well as the small front cover, your machine should now be ready for normal operation. You will have a few parts left over after reassembly. They will include; 1 daughterboard, 3 plastic standoffs, 2 ROMS, and 6 small screws. These parts should be saved just in case you have need of them in the future, besides, the daughterboard is a valuable commodity as CBM does not sell them as spare parts. This project has been successfully tested with the following combinations of system configurations; Spirit Technologies IN1000 memory card with 1.5 megs installed, the Palomax hard drive interface kit, a Ronin Hurricane Accelerator card (with and without memory card), and an ASDG memory box. For those of you who do not feel comfortable etching or wire wrapping your own boards, we have a printed circuit cards, PALs and the other components available. The bare card is $15, set of PALs is $15. For JED file or PAL equations, send SASE. Inquire about user club quantity discounts. You can order from: George Gibeau, Jr. Dept. of Biology - ML06 University of Cincinnati Cincinnati, Ohio 45221-0006 UseNet ggibeau@ucqais.uc.edu Parts sources: Digi-Key Corporation P.O. Box 677 Thief River Falls, MN 56701-9988 1-(800) 344-4539 Kickstart, Amiga, and A1000 are trademarks of Commodore Business Machines Flux-Off is a trademark of Chemtronics Palomax is a trademark of Mr. Jack Koehler of Palomax, INC. PIN LIST FROM ROMS ON ADAPTER BOARD TO SOCKETS ON MOTHERBOARD. ROM PIN U5P PIN U5N PIN SIGNAL 1 14 or 14 GND (A18* for future 512K ROMs) 2 3 or 3 A8 3 4 or 4 A7 4 5 or 5 A6 5 6 or 6 A5 6 7 or 7 A4 7 8 or 8 A3 8 9 or 9 A2 9 10 or 10 A1 10 14 or 14 GND 11 14 or 14 GND 12 22 or 22 ROM* 13 11 -- D0 14 -- 11 D8 15 12 -- D1 16 -- 12 D9 17 13 -- D2 18 -- 13 D10 19 15 -- D3 20 -- 15 D11 21 28 or 28 +5 VOLTS 22 16 -- D4 23 -- 16 D12 24 17 -- D5 25 -- 17 D13 26 18 -- D6 27 -- 18 D14 28 19 -- D7 29 -- 19 D15 30 14 or 14 GND 31 14 or 14 GND (A18* for future 512K ROMs) 32 20 or 20 A17 33 1 or 1 A16 34 27 or 27 A15 35 26 or 26 A14 36 2 or 2 A13 37 23 or 23 A12 38 21 or 21 A11 39 24 or 24 A10 40 25 or 25 A9 ------------------------------------------------------------------------- Hopefully this will make using your A1000 a tad bit easier, it is always good to give something back to the Amiga community. Regards, George -- UUCP: ucqais.uc.edu!ggibeau BBS: (513) 721-3016 Expert Services - the Rejuvenator people - (606) 371-9690 President of the Ohio Valley Amiga Users Group (Amigas - We DON'T have to do windows!)