Date: 8 Dec 90 02:39:10 GMT From: noao!ncar!elroy.jpl.nasa.gov!sdd.hp.com!wuarchive!zaphod.mps.ohio-state.edu!magnus.ircc.ohio-state.edu!news@arizona.edu (Frank E. Seipel) Subject: Atari in a PC Case (Hardware Mod.) To: Info-Atari8@naucse.cse.nau.edu This is another text file I had laying around.. If you'd like to see more, please E-Mail me. I think this file is formatted to be output to a printer. ATARI---->PC Conversion Page 1 THE FOLLOWING INFORMATION IS PRESENTED TO ASSIST THOSE INTERESTED IN CREATING A CUSTOM ATARI COMPUTER SYSTEM IN AN IBM 'PC' CASE. IT IS BY NO MEANS MEANT TO SERVE AS A COMPLETE DESCRIPTION OR 'HOW-TO-BOOK' ON THE SUBJECT AND IT IS ASSUMED THAT THE PERSON WHO UNDERTAKES THIS PROJECT IS WELL VERSED IN BUILDING ELECTRONIC PROJECTS. THIS INFORMATION IS PRESENTED BY MICRO SOLUTIONS FOR USE IN THE PUBLIC DOMAIN. >>>SPECIAL NOTE:MICRO SOLUTIONS WILL NOT BE HELD RESPONSIBLE FOR SPONTANEOUS MELTDOWN OF YOUR COMPUTER OR PERIPHERAL EQUIPMENT DUE TO THE UNDERTAKING THIS PROJECT. So you want to put you're ATARI into a 'PC' CASE.... Basically what's needed is: A thorough understanding of basic electrical circuits, soldering skills, some mechanical ability, and of course an IBM style case to your liking. These cases have become quite popular and are offered in numerous configurations. The main thing to remember when selecting one of these is, will your motherboard fit inside it without TOO MUCH modification? (Let's try to keep the SKIL saw in the closet for this project.) Another consideration, is whether or not you wish to have a HardDrive as part of this All-In-One system. Choosing an XL or XE computer makes this a much more viable possibility, because of the parallel expansion buss and the various HardDrive interfaces designed for this buss. Last, but not least, is the very likely addition of a TransKey board to enable the use of an external IBM style keyboard (well.... you know I had to say something about my product in this article). Most of these 'PC' computer cases on the market also come with a fairly beefy switching power supply capable of running the Computer, extra RAM, Disk Drives, and various hardware enhancements. To fully take advantage of this built-in power supply requires some rewiring of many of the stock Atari power plugs and devices. To minimize some of this and to better utilize your storage media, it is recommended that XF551 drives be used in this project. The nice thing about these drives is the fact that they are really IBM type drive mechanisms in disguise, this allows for a simple bolt-in, no modification installation. The power connection on these drives will readly accept the supplied power connectors on the switching supply and the drives will give you 360K storage per disk with a suitable DOS (ie: MYDOS or SPARTADOS). The XF controller (the PCB included with the XF551 drive) will need some slight modifications as follows: 1) After seperating the two halfs of the original XF551 plastic enclosure, unscrew the 4 screws holding the drive in place. 2) Unplug both the 34pin and 4pin connectors from the drive, then lift it out of the enclosure and set it to the side. 3) You will now find a couple of screws holding the PCB to the bottom of the enclosure. Remove these and lift the PCB straight up and ATARI---->PC Conversion Page 2 out. 4) Desolder the 34pin header (w/cable) from the PCB and replace it with an IDC style male header. 5) Clip off the 4pin female molex type power plug while leaving the connection wiring intact. Now replace this with a male 4pin IBM floppy power connector, being sure to matchup the PCB silkscreen designations with the proper pin numbers (pin1=+12vdc pin2=GND pin3=GND pin4=+5vdc). 6) Use a standard IBM drive cable to connect the drive to the controller card. These cables normally have two edge card connectors on one end, the END one is the one to use. 7) Now plug in power connectors from the switching power supply to the Disk Drive and also to the controller. The drive is now ready to use (be sure to set the drive select switches on the controller to the desired SIO #). If you wish to use a 3.5" drive(s) in your system and wish to have them be capable of 720K storage, a complete kit and instructions are available from Innovative Concepts. If you don't require the full capacity, but would still like to use one of these smaller drives then the following instructions are for you. 3.5" Drive Conversion: Using the controller as first modified, connect a 3.5" IBM drive in place of the 5.25" drive (this will usually require adapter plugs that normally come with the drive when purchased). No further modifications required. Dual Media Drives from one Controller: 1) After performing the controller modifications already listed, turn over the PCB and locate pins 10&16 on the 34pin header. You will notice a trace connecting these pins together and another trace leading towards the center of the board from pin16. Cut the trace between pins 10&16 with an XACTO knife or razor blade, being sure to leave the other trace on pin16 intact (this is the drive select line from the floppy controller chip). 2) Solder a wire from pin16 to the center of a SPDT toggle switch. 3) Solder a wire from pin10 to one side of the switch and solder a wire from pin12 to the other side of this same switch. 4) Plug the other unused 34pin edge card connector on the floppy drive cable into the 3.5" IBM drive (this may require an adapter). ATARI---->PC Conversion Page 3 Also, plug in a power connector from the switching power supply (this may require an adapter as well). 5) The SPDT toggle switch will now select which drive will respond off of this controller (either the 5.25" or the 3.5"). Pin10=Drive 1 Select, Pin12=Drive 2 Select, 34pin edge card END connector=Drive 1, middle connector=Drive 2. With this setup you will be able to use either the 5.25" or 3.5" drive with but one controller. Both drives will be capable of 360K of storage. Only one drive is usable at any given time from the one controller (Disk duplication and/or copying between the two drives is not possible). A second controller and drive will still be needed for disk duplication and/or copying. Computer Power Connection: For simplicity, a 600/800XL or XE are the computers of choice in this situation. The reason; only a single +5vdc supply is needed, where as the earlier 400/800 models and the 1200XL required either 9vac or if bypassed; +5vdc, +12vdc, -5vdc. The +5 and +12vdc is readly available off of the IBM switching supply, but the -5vdc or 9vac isn't. You could of course kludge up some sort of supply to handle this, but in the long run, the XL/XE's are better for other reasons as well (parallel buss & built-in BASIC to name a few). The 600/800XL and XE's use the same power connection plug, this is a 7pin DIN (an 8pin DIN can be subsituted by removing it's center pin). On this plug pins 1,4,6=+5vdc and pins 2,3,5,7=GND. Either cut off one of the provided power connectors on the switching power supply and subsitute a DIN plug or better yet, make up a 4 pin male floppy power pigtail with a DIN on the other end. Only +5vdc and GND are required on this connection. Hard Drive Installation: To install a HardDrive with high speed access will require an XL or XE computer having the External Parallel Buss (often times called PBI or ECI). It is through this parallel buss that a special drive controller will be connected, offering an industry standard HardDrive interface referred to as SASI or SCSI. To the best of my knowledge there are currently three such devices available, the CSS Black Box, ICD's MIO, and Supra's Hard Disk Interface. Any of these is suitable for putting a HardDrive in your system, merely requiring the appropriate SASI or SCSI controller and drive. If you're willing to sacrifice speed and if you can find it, there is an SIO connectable device that will give you HardDrive interfacing. It was called the ATR8000, actually a complete computer on it's own, which used the Atari as a terminal link. With the right ATARI---->PC Conversion Page 4 options, this Co-Processor board was capable of accessing HardDrives. Even without extra options, the ATR8000 would allow for connection of up to 4 IBM style Floppy disk drives, looking for the most part, as 4 Atari drives on the SIO port. It is also my understanding that higher capacity drives were possible through special configuration, allowing up to 1.2 MEG with the proper drive and DOS. There will be some problems with this interface, such as not 100% compatibility with all Boot Disks and/or DOS'es and very slow HardDrive access, otherwise it is a good alternative for 400/800 users especially. Some of the other advantages to the parallel buss devices, is that they usually do more than just allow for HardDrive connection. To name a few; extra expansion RAM usable as a RAMDISK, RAM for Print Spooling, RS232 Port, Parallel Printer Port, and built-in Machine Language Monitor. Not all features are offered or are all available from any one device. The CSS Black Box is slated for a floppy drive interface enhancement, possibly similar in nature to the ATR8000,s floppy interface. This would give you an all in one drive controller that's also fast. Most of the parallel interfaces will require some relocation in order to fit inside your 'PC' case. This amounts to fabrication of ribbon cable extensions in some cases, which may be as simple as using crimp-on connectors or as difficult as point-to-point wiring depending on the interface and computer choosen. My actual experience was with a Black Box and a 800XL computer. This was relatively simple, amounting to building a cable from one 50pin edgecard connector, one 50pin female IDC plug, and about 12" of ribbon cable. Both connectors were of the crimp-on variety, making for a no solder installation. When making your own cables, be sure to always line-up the pin#1's on both sides. With the flexability of the interconnecting ribbon cable, you should be able to fit both the computer motherboard and the parallel interface board into most any 'PC' case. A little imagination is most useful in this task and good mechanical know how is imperative. Boards can be stood on end or stacked, just depends on the particular situation and alot on what you perfer to do. Find yourself a good supplier of mechanical spacers, fasteners, and PCB guides, because you'll be knee deep in them before your'e done with this project. Power for your parallel interface can most likely be derived from one of the floppy power connectors on your 'PC' switching power supply. Once again it will require some rewiring of connectors and some good electrical sense. Power for the HardDrive and it's associated SASI/SCSI controller, will normally be as simple as plugging straight into one or two of the leftover floppy power connectors (by this time we may have exhausted all the available connectors, have no fear there are 'Y' adapters available). Now comes a problem, most HardDrives need a few seconds to rev-up to full speed when first powered up. During this time they are not accesable from the controller and many times this can result in bootup ATARI---->PC Conversion Page 5 errors. One possible solution would be to provide a seperate power switch on the front panel for the Atari computer, switching it on after the HardDrive was up to speed. Another solution is something I came up with on my system, a computer power delay timer. This consisted of a 555 timer with it's trigger line tied to it's timing capacitors positive side, a 5vdc SPST relay on the output of the 555 with the common of it's coil and switch going to +5vdc, and the entire affair wired in series with the computer power line. Basically what happens is, that upon power-up, the timer's output will immediately go positive, thereby causing the relay to do absolutely nothing. After the timer times out (depends on the RC network used), the output will drop to GND causing power to flow through the relay's coil, pulling the switch closed, and allow power to go to the computer. 555 pin #s +5VDC---[:::]--2-6--+)(---GND 220 47uf K 1--------GND +5VDC----------4 " ----------8 *RELAY* +5VDC--[COIL]--3 *RELAY* *SWITCH* +5VDC----o/o-----[ATARI]--GND +5VDC----[<]---3 1N4004 The idea is to pick an RC network that gives sufficient time for the HardDrive to rev-up, I found 220K for the timing resister and 47uf for the timing capacitor to be quite good for my Seagate drive (this gives about a 15 second delay). Increasing the resister's value will result in a longer time delay and decreasing it, will produce a shorter delay. It is also advisable to use a relay who's contacts are rated for 1.5 amps, and for protection against arcing, solder a .01uf capacitor across the contact connections. Also, to protect the 555 timer from high EMF voltages that may be generated by the relay's coil, solder a 1N4004 diode across the coil with it's cathode (marked with a line) going to the +5vdc side. Another rather nifty feature of this power-up delay timer, is that it offers an easy way to perform a ColdStart Reset for owners of the TransKey board (there I go again). To do this, take the Gray wire from the TransKey board, and instead of attaching it as suggested in it's original instructions, solder it to pin2 of the 555 timer instead. Now everytime you do a RESET from the IBM keyboard (attached to TransKey), you will shutdown the power to the Atari computer for ATARI---->PC Conversion Page 6 the duration of the time delay. This will of course result in a ColdStart Reset, just as if you had reached around back and shut off the computer's power switch and then turned it back on again. The main advantage is that you don't need a special O.S. or software routine to provide this keyboard coldstart reset. Cartridge Port: This is where things get alittle tricky.... How do you get access to the Cartridge Port once your Atari is tucked inside the 'PC' case? Well the best solution I have seen, is something that Bob Woolley from San Leandro Computer Club (SLCC) came up with. Essentially what he did was to take one of those 34pin IDC edge card connectors (yes, the same one used for the IBM floppy drive cables) and with a little filing on the ends, he was able to insert this inside the plastic cartridge shrouding that came with the Atari motherboard (that's right you have to remove it from the board first). He then had a ribbon cable extending from this connector about 10-12 inches connecting to the Atari motherboard via a 34pin connector (this required desoldering the original cartridge socket & replacing it with wirewrap pins extending out the backside of the board). The completed assembly was then meant to be mounted behind a 3.5" drive bezel for insertion of the cartridge from the frontside of the 'PC' case. For more complete information with pictures on this modification, consult the May 1990 issue of the SLCC Journal. ***HINT: keep the ribbon as short as possible for reliable cartridge operation*** Conclusion: There are of course many other things that can be put inside your new 'PC' case, but only you can decide what's best for you. Most importantly, plan out this project carefully before you purchase your 'PC' case and be sure to leave yourself sufficient room for future additions. (This will keep you from having to start all over again... Yuck!) Most of all, have fun with your new ATARI PC and enjoy the looks of approval you'll get from those unsuspecting IBM'ers out there. Sources for Items Mentioned: BLACK BOX Computer Software Services P.O. Box 17660 Rochester,NY 14617 (716)586-5545 MULTI-IO (MIO) ATARI---->PC Conversion Page 7 ICD 1220 Rock Street Rockford,IL 61101 (815)968-2228 SUPRA HARDDRIVE INTERFACE BEST Electronics 2021 The Alameda STE 290 San Jose, CA 95126 (408) 243-6950 XF35 KIT Innovative Concepts 31172 Shawn Drive Warren,MI 48093 (313) 293-0730 TRANSKEY (IBM keyboard interface) Micro Solutions P.O. Box 750396 Petaluma,CA 94975 Genie M.ST.PIERRE1