_________________________________________________________________________ | ATARI 7800 DEVELOPMENT SYSTEM | | | | - PAL CONSOLE MODIFICATION | | - VARIOUS NTSC/PAL DEVELOPMENT CARTRIDGE MODIFICATIONS | |_________________________________________________________________________| AUTHOR: Graham.J.Percy EMAIL: gjp57@yahoo.com PHONE: + (61) 03 5978 7198 FAQ Version 1.19, 3rd September, 2001. Copyright (c) 2001 Graham.J.Percy All rights reserved. This document may be reproduced, in whole or in part, provided the copyright notice remains intact and no fee is charged. The data contained herein is provided for informational purposes only. No warranty is made with regards to the accuracy of the information. *************************************************************************** ________________ | | | INTRODUCTION | |________________| This document has been written as a supplement to instructions for making the Atari 7800 Development System and cart dumper by John Saeger and Eckhard Stolberg. For the most recent version of the system mod instructions refer to:- http://buerger.metropolis.de/estolberg/tools/ Or search for "7800 development system" First in this document is a description of how a PAL 7800 console was fitted with a DevOS BIOS rom chip. The console was originally purchased in Australia (with the built in game Asteroids). Secondly, a number of development cartridge modifications are described. For the most part they require a common cartridge PCB like that found in Choplifter (PAL). The simplest 48K dev cart requires only two jumpers. *************************************************************************** _____________________________ | | | MODIFYING THE PAL CONSOLE | |_____________________________| CONSOLE:- Atari Model No.7800 PAL B Made in China S/No. A1(084)5029749 Motherboard P/No. C300633-001 Rev C DevOS BIOS CHIP:- The following Eproms have been used successfully for console conversion:- 24-pin 4K (2732) 28-pin 8K, 16K, & 32K (DevOS copied to last 4K of chip). INSTALLING THE DevOS BIOS CHIP:- 1/ Remove component W6 and install at location W5. (W6 is in the front-right corner of the motherboard). 2/ For a 24-pin eprom only, remove component W2 and install at location W3. (W2 is located to the left of the socketed BIOS chip). 3/ Remove the original BIOS chip (P/No. C300558-001) from it's socket. Insert the new BIOS chip with the same orientation. For a 24-pin eprom, install at the extreme right of the socket. BTW, the built in game is not supported by the DevOS BIOS. *************************************************************************** ____________________________________ | | | PARTS REQUIRED FOR DEV CART MODS | |____________________________________| 1/ A suitable Atari 7800 game cartridge. Except for the "Pokey" Dev Cart which requires a Ballblazer cartridge, all modifications detailed in this FAQ are based on the Printed Circuit Board (PCB) part No.C300565-XXX. An Atari 7800 PAL game cartridge "Choplifter" was used for original modifications, game size 48K. Other PAL games which have been seen with this PCB are:- Alien Brigade Barnyard Blaster Crossbow Desert Falcon Donkey Kong Donkey Kong Jnr Food Fight Galaga Hat Trick * Impossible Mission * Jinks ? Joust Mario Bros. One On One Super Huey * Tower Toppler Xevious NTSC games which are known to use this PCB:- Barnyard Blaster Crack'ed Dark Chambers * Jinks * Tower Toppler * Winter Games (ntsc) * Note: Cartridge includes built in RAM. 2/ 32Kx8, 64Kx8 or 128Kx8 Static Random Access Memory (SRAM). In original modifications, cache and cmos memory from 486 and Pentium motherboards was used. Every type tried was found to work fine, although I did come across a couple of dud chips. The following types were used successfully (32K unless noted):- MANUFACTURER PART No. Alliance AS7C256-20PC AT & T ATT7C199P-20 EtronTech Em51256C-15PL Integrated Device Technology IDT71256-S25TP ISSI IS61C256A-20N Matra MHS HM3-65756F-5 Micron MT5C2568-20 Mosel MS62256A-25NC Motorola MCM6206DP20 Toshiba TC55328AP-20 United Microelectronics Corp. UM61256K-15 Winbond (32K 28-pin) W24257AK-15 Winbond (64K 32-pin) W24512AK-20 3/ Other parts as required. See below:- *************************************************************************** ___________________________________________ | | | 32K OR 48K DEV CART USING ONE SRAM CHIP | |___________________________________________| MODIFYING THE GAME CARTRIDGE:- 1/ If present, remove U1 (game rom) and U5 (74LS374) by filing through chip pins next to the chip body. 2/ Note that jumpers W1 through W6 have no affect on this modification so can be either on or off. 3/ This modification requires a 74LS02 logic chip at U3 and a 74LS00 logic chip at U4. If they are not already present then suck the solder out of U3 or U4 pin holes and fit the required chip(s). 4/ Ensure that R1 and C2 are fitted. If you plan on fitting a 32 pin SRAM (64Kx8 or 128Kx8) then locate R1 and C2 on the back of the PCB. Remove all other Resistors and capacitors. A black banded "resistor" or a wire jumper can be used at R1. Install a 0.1uF capacitor (labelled "104") at C2 if required. 5A/ 32K (USING 32Kx8 SRAM) ---------------------- a) Take a 28 pin, 32K SRAM chip and bend all the pins out to approximately 45 deg so that pin ends match hole positions of U2. Bend pin 20 (CS-) and pin 22 (OE-) up to horizontal and trim the narrow part of these pins leaving a small flap. Install the chip in the location reserved for U2. b) Jumper SRAM pin 20 (CS-) to 74LS02 pin 13. c) Jumper SRAM pin 22 (OE-) to 74LS00 pin 13. 5B/ 48K (USING 64Kx8 OR 128Kx8 SRAM) -------------------------------- a) Take a 32 pin, 64K or 128K SRAM chip and bend all the pins out to approximately 45 deg so that pin ends match hole positions of U2. Bend pins 1 (NC), 2 (A16), 22 (CS-), 24 (OE-), 31 (A15) and 32 (Vcc) up to horizontal and trim the narrow part of these pins leaving a small flap. Install the chip in the location reserved for U2 with pin 3 in hole 1. b) Jumper SRAM pin 22 (CS-) to 74LS02 pin 13. c) Jumper SRAM pin 24 (OE-) to 74LS00 pin 13. d) Jumper SRAM pin 30 to SRAM pin 32 (Vcc). e) Jumper SRAM pin 31 (A15) to 74LS00 pin 5 (A15). f) If you are using a 128Kx8 SRAM then Jumper SRAM pin 2 (A16) to SRAM pin 16 (GND). *************************************************************************** _____________________________________ | | | 48K DEV CART USING TWO SRAM CHIPS | |_____________________________________| MODIFYING THE GAME CARTRIDGE:- 1/ If present, remove U1 (game rom) and U5 (74LS374) by filing through chip pins next to the chip body. 2/ Note that jumpers W1 through W6 have no affect on this modification so can be either on or off. 3/ This modification requires a 74LS02 logic chip at U3 and a 74LS00 logic chip at U4. If they are not already present then suck the solder out of U3 or U4 pin holes and fit the required chip(s). 4/ Ensure that R1 and C2 are fitted. A black banded "resistor" or a wire jumper can be used at R1. Install a 0.1uF capacitor (labelled "104") at C2 if required. Remove all other Resistors and capacitors. 5/ Take a 28 pin, 32K SRAM chip and bend all the pins out to approximately 45 deg so that pin ends match hole positions of U2. Bend pin 22 (OE-) up to horizontal and trim the narrow part of this pin leaving a small flap. Install the chip in the location reserved for U2. 6/ Take a (second) 28 pin, 32K SRAM chip and bend the very ends (the last 2mm) of all the pins out to approximately 45 deg. This chip is to sit piggy-backed over the first 32K SRAM chip installed at U2 (per step #5). Bend pin 20 (CS-) up to horizontal and trim the narrow part of this pin leaving a small flap. Bend pin 22 (OE-) so that it meets pin 22 (OE-) on the first sram chip when the two chips are placed together. Install the second chip directly on top of the first. All but pin 22 (CS-) are to be soldered to matching pins on the first chip. NOTE:- Route the following jumpers around the ends of the SRAM chips to allow clearance for the piggy-backed chips inside the cartridge case. 7/ Jumper U2(Top) pin 20 (CS-) to U3 pin 4 (A15-). 8/ Jumper U2(Top) and U2(Bottom) pin 22 (OE-) to U4 pin 13 (R/W-). *************************************************************************** ________________________________________ | | | MAKING USE OF BUILT-IN CARTRIDGE RAM | |________________________________________| A few of Atari's 7800 game cartridges come with a RAM chip already fitted in U2. (eg. Jinks, Tower Toppler, Winter Games). It is possible to make use of this RAM chip. Start by completing steps 1 through 4 of either the one-SRAM or two-SRAM dev cart modifications detailed above. Finally, complete steps detailed below for either a 32K or 48K devcart:- 32k DEV CART USING EXISTING RAM CHIP:- RAM pin 20 (CS-) is connected by a single trace to U4 pin 3. (This is the only trace connecting to U4 pin 3). Locate this trace on the back of the PCB in the vicinity of U4 and cut or file it through. Jumper RAM pin 20 (CS-) to U3 pin 13. The size of the dev cart will depend on the size of the original RAM chip fitted to the board. In all likelihood the installed chip will be 32K (eg. CXK58256P-12L) in which case you will have a 32K dev cart. 48K DEV CART USING EXISTING RAM CHIP PLUS 32K SRAM:- Take a 28 pin, 32K SRAM chip and bend the pins out almost to horizontal so that they rest against the edge of the existing RAM chip when placed piggy-back over it. Bend pin 20 (CS-) and pin 22 (OE-) up to horizontal and trim the narrow part of these pins leaving a small flap. With the SRAM chip piggy-back over the existing RAM chip bend the very ends of all remaining pins over the edge of the RAM chip to touch it's pins. Install the second chip directly on top of the first. All but pin 20 (CS-) and pin 22 (OE-) are to be soldered to matching pins on the existing RAM chip. NOTE:- Route the following jumpers around the ends of the SRAM chips to allow clearance for the piggy-backed chips inside the cartridge case. Jumper U2(Top) pin 20 (CS-) to U3 pin 4 (A15-). Jumper U2(Top) pin 22 (OE-) to U4 pin 13 (R/W-). *************************************************************************** ____________________________ | | | EEPROM SOCKETED DEV CART | |____________________________| This modification is yet to be tried successfully, but if you want to give it a go yourself here are the details:- The 7800 development system can be used to programme Electrically Erasable and Programmable Read Only Memories of the type 28XXX. This type of memory chip is programmed using a single 5V power source and so is ideally suited for use on the 7800 development system. FEATURES:- 1/ This dev cart uses circuit logic from the original 32K dev cart. EEPROMS must have pin-outs compatible with those shown for the 28-pin SRAM shown in dev_sys4.pdf. The more common compatible types are 2864 (8K x 8) and 28256 (32K x 8). 2/ The EEPROM is mounted in U1 allowing access while the cartridge is inserted in the console. 3/ A large area around U1 has been made clear to allow installation of a Zero Insertion Force (ZIF) socket if required. (Maximum foot print is approximately 26mm x 58mm). MODIFYING THE GAME CARTRIDGE:- 1/ Remove all chips U1 through U5 by filing through chip pins next to chip bodies. Remove all remaining pin legs and suck the solder from holes for U1 and U4. 2/ Ensure that jumpers W2, W4, W5 and W6 are open (Not bridged). On some PCBs the jumpers are bridged by a small trace that is not obvious. If so, then cut or file these traces through. 3/ Ensure that jumpers W1 and W3 are bridged. Add a dolop of solder if required. 4/ Ensure that R2 and C1 are fitted. Locate R2 and C1 on the back of the PCB. Remove all other Resistors and capacitors. A black banded "resistor" or a wire jumper can be used at R2. Install a 0.1uF capacitor (labelled "104") at C1 if required. 5/ Install your 28-pin Dual In line socket at U1. 6/ Take a 74LS00 logic chip, bend pins 8 and 9 up to horizontal then trim off the narrow part of these pins leaving a small flap. Install chip at U4. 7/ Use solder to bridge U4 pin 4 to pin 5 and U4 pin 9 to pin 10. 8/ Jumper U4 pin 6 (A15-) to U3 hole 13 (CS-). 9/ Jumper U4 pin 8 (R/W-) to U4 pin 13 and U5 hole 6 (OE-). 10/ Jumper U4 pin 11 to U5 hole 2 (WE-). 11/ Jumper U5 hole 1 (A14,edge) to U5 hole 5 (A14,EEPROM). *************************************************************************** ________________________ | | | 32K "POKEY" DEV CART | |________________________| This development cartridge supports 7800 programmes that use Atari's multi- purpose Pokey chip. It also supports the same games as a regular 32K dev cart. DESIGN:- 1/ A Ballblazer cartridge is required for this modification, PCB part number C026461. Atari's Pokey chip comes fitted at U3. 2/ The memory size is limited to 32K because the Pokey chip uses the first 16k of the available 48K memory address space. 3/ This design relies on WE- over-riding OE- during write cycles. This works fine with all SRAMs tested to date. (See "Parts Required for Dev Cart Mods"). MODIFYING THE GAME CARTRIDGE:- 1/ Remove U1 (game rom) by filing through chip pins next to the chip body. Remove remaining pin legs. Suck the solder out of holes reserved for U2. 2/ Move the jumper at W1 from [1-2] to [2-3]. Legend:- 3 2 1 +---------------------+ | +---+ | | o o | o | | | +---+ | +---------------------+ 3/ Remove jumpers at W2 and W3. 4/ Take a 28 pin, 32K SRAM chip and bend all the pins out to approximately 45 deg so that pin ends match hole positions of U1. Install the chip in the location reserved for U1. 5/ On a 74LS00 chip, bend pin 2 up to horizontal and trim off the narrow part leaving a small flap. Install in location reserved for U2. (Note:- Orient the chip with pins 1 and 14 at the top end of the PCB). 6/ Jumper U2 pin 8 to W2 hole 2 (WE-). 7/ Jumper U2 pin 9 to U3 (Pokey) pin 7 (CLK2). 8/ Jumper U2 pin 12 to W2 hole 3 (R/W). 9/ Bridge U2 pin 1 to 2, pin 10 to 11 and pin 12 to 13. 10/ On the back of the PCB, bridge U2 hole 2 to pin 3 (CS-). *************************************************************************** ____________________ | | | ACKNOWLEDGEMENTS | |____________________| Thanks to John Saeger and Eckhard Stolberg for their brilliant 7800 Dev System and for their generous support. Thanks to Dan Boris for advice on SRAMs and for 7800 cartridge info (7800cart.txt) Thanks to K.Horton for sparking my interest in Activision's bankswitching chip. (chips.txt) *************************************************************************** FILE:- DEVOSPAL.TXT