From merk!kosmos.wcc.govt.nz!sheppard_r Tue Oct 27 06:58:40 1992 Received: by harvee.billerica.ma.us (HERMES RMAIL 1.04 Rev. Sep 5 1992) id <0BWRN9S@harvee.billerica.ma.us>; 27 Oct 92 06:58 -0400 Received: by merk.merk.com (/\==/\ Smail3.1.25.1 #25.17) id ; Tue, 27 Oct 92 04:36 EST Received: by kosmos.wcc.govt.nz (MX V3.1C) id 8461; Tue, 27 Oct 1992 21:32:54 +1200 Date: Tue, 27 Oct 1992 20:34:34 +1200 From: sheppard_r@kosmos.wcc.govt.nz To: esj@harvee.billerica.ma.us Message-ID: <00962BBF.AD431140.8461@kosmos.wcc.govt.nz> Subject: Re: D.I.Y. 4 Meg upgrade??? One of the ultimate ironies of the Atari ST system is that the computer is not upgradeable. I'm sure that many people from other computer platforms would be very quick to agree. Many others, such as Dave Small, and probably the people at ICD INC would take some small exception to this idea. I too would have to take a minor exception. Because of the relatively closed architecture of the ST this computer system has become a hackers heaven. It is with this in mind that I have written this recount of my experiences using SIMMs to upgrade STs to 2 1/2 megs. It seems like each time I read an article about upgrades there is a long warning about warranties and technical competence. Why should I care if you ruin your computer? As far as your warranty goes, if you remove the screws on the bottom your warranty is void. My upgrade will cause your warranty to explode and possibly ruin your computer desk in the process. There is the small reminder that since the warranty is only 90 days in the first place, the odds of your warranty being valid at this time are nill. One small consolation, if you do ruin your computer while attempting this upgrade you can always buy an STe and use the SIMMs there. The reasons I developed this particular style of upgrade are two fold. The first is that I just wanted to see if I could do it. The second has to do with my personal feelings about sockets that plug into existing chip sockets and cause permanent damage. There are a couple of advantages to my upgrade techniques. 1} I use SIMMs, which are noted for their reliability. 2} All connections are soldered which means no sockets to ruin and if properly done provides extremely reliable long term operation. Since you are probably going to try this anyway, you should go ahead and get yourself a pair of 1 meg x 8 SIMMs. If you should happen to get the 1 meg x 9 SIMMs, that is ok too. The speed isn't that important, but it is hard to find a set of SIMMs these days slower than 100ns anyway. While you are in the getting mode, get yourself a few feet of 28 gauge Kevlar wire such is used for wire wrapping, a few bits 8" of 7 stranded hookup wire, a 1/8 w 33 ohm resistor, double sided mounting tape, a hot glue gun, plus a Fluke Model 73-77 digital meter, plus a good solder sucker. You will also need a decent temperature controlled soldering iron running between 750 and 800 degrees. Take your 25 watt Radio Shack type iron and throw it away while you are at it. Those small and unregulated irons are a good source of just the right types of static known for killing CMOS circuitry dead. I should also mention the fact that the longer a soldering iron remains on the circuit board, the greater the chances are that you will begin destroying the foil patterns. The major problem I have encountered while upgrading STs is the numerous version revisions. There are no fewer than 6 different styles of mother boards and many of them use different circuit symbols for the various components. For this reason I will not be referring to any of the components by their circuit symbols. All references will be by component name, such as the MMU, or the upper and lower RAM banks. I simply have to assume you know what your are doing. I begin the upgrade by removing the mother board from the computer and placing in on an anti-static workbench. Depending on the model of computer, the upper or lower bank of ram chips must be removed. By upper bank I mean the row of chips connected to the CAS1, and RAS1 lines from the MMU chip. You may verify this by measuring from pins 18, 21, and 22 of the MMU chip. CAS1 H = 22, CAS1 L = 21, and RAS1 = 18. The corresponding locations of the CAS and RAS lines on the ram chips are pins 15 for CAS and 4 for RAS. NOTE: ** RS. The banks that you use does not matter..** The ST uses two rows and four columns of ram chips in their memory addressing scheme. The Row Address Strobes ( RAS ) are labeled RAS1 and RAS0, and the Column Address Strobes ( CAS ) are labeled CAS1 H, CAS1 L, CAS0 H, and CAS0 L where the H and L stand for High and Low. All the lines using the 1 are related to the the upper row and the lines labeled with the 0 are used in the lower row. You will probably not find the above mentioned labels printed on your particular mother board. The only time I remember seeing this done was on the 520ST with modulator. Don't expect it. If you are wanting to do this upgrade on the early 520 you should remove the entire set of ram chips. Your final upgrade will be 2 megs instead of 2.5. There is just no clean way to install all the wiring needed to installed chips. Once the ram chips are removed it is time to mount the SIMMs and prepare the wiring. On the machines where the ram chips are mounted under the keyboard, there is a good place to mount the SIMMs right above the upper bank of ram chips. I use strips of double sided adhesive foam which I attach to the back of one of the SIMMs. I then stick this SIMM to the mother board. When the SIMM is mounted it is about 3/4 inch above the spot where the ram chips were removed. I then take another strip of adhesive foam and cut it to a width of 1/4 inch. This strip is placed on the top rear of the SIMM I just mounted on the board. Now I carefully place the second SIMM directly over the first. It is important to line the two SIMMs up so that they match exactly. When completed I have the two SIMMs stuck together, with one on top of the other. From this time on, consider the top SIMM to be the "High" and the bottom SIMM to be the "Low" column. For the STs with the ram under the keyboard, the upper bank of ram chips just happens to be the ones farthest away from the front of the machine. It also happens that the "High" column is o the left and the "Low" column is on the right. To make remembering easier I use a marker and mark the center between the two columns. That make eight on the left and eight on the right side of the mark. If you have one of the STs with the ram under the powersupply, you will need to use the Diode Option of say a Fluke Digital meter 73-77 and verify the locations of the upper and lower banks. While I have looked at one of these beasts I have not done an upgrade on this particular style so I cannot suggest a location for the SIMMs. ** RS. I suggest infront of the power supply, remove the Rams next to the Cartridge socket, the SIMMS were stuck on top of a IC there, with also the use of a Hot Glue Gun to hold the ends of the SIMMS in place.. ** The following pinouts will be critical to your successful upgrade: 1 meg x 8 SIMM 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | V C D A A D A A V D A A D A A D A A N D W V D N D N R V V V C A Q 0 1 Q 2 3 S Q 4 5 Q 6 7 Q 8 9 C Q E S Q C Q C A C C C C S 0 1 S 2 3 4 5 S 6 7 S C C C 256K DRAM Pinout 1> A8 16> VSS 2> Din 15> CAS 3> WE 14> Dout 4> RAS 13> A6 5> A0 12> A3 6> A2 11> A4 7> A1 10> A5 8> VCC 9> A7 If you notice, there is no A9 on the ram chips. This is the new address line and special consideration is required. I will cover this further on. I start by making a check list numbered from 1 to 30 with two columns, one for the upper and one for the lower columns. PIN 1 and 28,29,30 also.. Beginning with pin 1 on the SIMMs take the kevlar wire and strip back about half an inch. The neat thing about the wire is that it fits perfectly into the holes on the SIMMs. Since the Vcc line is common to both SIMMs I insert the wire into the lower SIMM and solder it into place. I then attach the wire to the upper SIMM and solder it. Because the Vcc line is what it is, I now use a slightly larger gauge wire and run it from pin 1 of the SIMM to pin 8 of the nearest vacant ram. In order to keep things neat, I keep the wires as short as possible without any undue stress. Do the same for PIN 30, but also connect PINS 28,29 to PIN 30, on top and bottom SIMMs, so there are 2 Vcc lines from the SIMMs to 2 ic pin 8's. Since I removed the 16 ram chips I have my choice of spots for the placement of the wires run from the SIMMs. The following considerations should be taken into account. The address lines A0 through A8 are common to all the chips. The CAS lines are split so CAS H is common to the upper column of 8 chips and CAS L is common to the lower 8 chips. The RAS line is common to all 16 chips. The DQ lines are separate and require special wiring. PIN 2 The CAS line on pin 2 of the SIMMs needs to be split up. The lower SIMM is wired to any convenient pin 15 of the lower column. The upper SIMM is wired to pin 15 in the upper ram column. PIN 3 DQ0 is split. The lower SIMM is run to the first chip socket of the lower column. This should be the chip closest to the spot previously marked as the center. Both columns run from left to right. The DQ label corresponds to the Din or pin 2 of the ram socket. The upper SIMM is wired to the ram socket farthest to the left. PIN 4 A0 should be wired from the lower SIMM to the upper SIMM. It should then be wired to the nearest ram socket pin 5. The only major concern here is neatness. PIN 9 and 22 These are the Vss pins, connect lower to upper with the Kevlar wire, then use the thicker wire from SIMM pin 9 to ram pin 16, also do the same for SIMM pin 22 to another ram pin 16. The rest of the wiring follows the same order listed above. Pin 21 of the SIMM should be jumpered between the two SIMMs and then run to ram pin 3. Pin 27 of the SIMMs is also jumpered between the two SIMMs and then run to ram pin 4. PIN 18 The A9 line is the new address line which is required when 1 meg chips are used. This line should also be jumpered between the two SIMMs. Using the Kevlar wire I run to one of the holes where the ram chips were removed. What I like to do is drop the insulated wire through the hole and run it over near the MMU. The idea here is to run the wire from the SIMMs pin 18 through a 33 ohm 1/8 w resistor (which you need to come up with) to pin 64 of the MMU. I like to use a little shrink tubing over the resistor connections since this is an outboard hookup. Using a couple of convenient holes for wire routing simply makes for a neater job, the hot glue gun can be used to hold this wire in place under the P.C.B.. I follow my check list exactly and mark each connection as it is made. Since the key to a well done job is top quality craftsmanship, I am careful to do the best job I am capable of. This completes the upgrade. If you want to go to 4 megs all you need to do is make a few minor changes. Remove all the ram chips and of course use 2 pairs of SIMMs. Wire one pair into the upper bank position and the second pair into the lower bank position. You do not need to do anything about swapping the CAS and RAS positions. I would like to suggest that you get ahold of some type of memory tester program. There is one in the GEnie library written by Barry Orlando which will do the job nicely. Another program written by Willie Brown does a good job as well. It is also possible to use NeoDesk to look at but not test our memory. With Neo Desk simply click on the desktop info and read the screen. there is a line at the bottom of the screen which identifies free memory. I will admit that once or twice my upgrades did not work at first and required some trouble shooting. If this is the case, you will need to double check your work. Each time I had trouble it was caused either by a faulty solder connection.. There is one other place you may get some trouble. If you are upgrading from 512k and the computer has never had a memory upgrade before, there is a possibility that the MMU chip could be bad. This can occur because the CAS1 and RAS1 lines have never been used or tested. I ran into this problem once. It also doesn't hurt to remove and clean the MMU and its socket. This can pay off on the older machines. Just in case I have inspired you to go out and do this upgrade, let me advise you that it takes me about 6 hours to do this job. Using a good desoldering machine to remove the old ram chips takes about 1 hour. You could also use a fine pair of cutting pliers and clip out the chips. This would be much faster, but I like to save the chips for other projects. The fastest upgrade I did was on a 520STFM where the 1040 mother board was used. There were no ram chips to remove. Now that it is all done, it is time to sit back and enjoy your work. 2.5 megs is a pretty nice upgrade. The cost was fairly reasonable, the SIMMs cost $90 to $110 a pair and 100 feet of Kevlar wire costs about $5 bucks. The only other cost is for the resistors and depending on the computer you will need from 1 to 4 of them. I recommend using 1/8 watt 33 ohms. I hope that this information is of some value to those of you who have read it. You may use this document in your club news letters or magazines provided it is printed in its entirety. You may not remove my byline cause I need some claim to fame. Finally if you should choose to perform this upgrade and kill your computer, you can always buy an STe and sell your dead computer to me, really cheap. Heck, I can always use a few more spare parts. Paul Gittins Portland Atari Club, PAC GEnie id: P.Gittins Rogers bit... MMU Pins. The dimple is located over pin 1.. 43________27 44| |26 61.62.63.64.65.66.67.68.1.2.3.4.5.6.7.8.9 | | G M | MMU | N A | | D D | | 9 60-----*-----10 61 1 9 NOTE: 4. 33 ohm resitor goes on pin 18.. A9.. PINs 28/29 are inputs SIMMs bit 9, I connected them to pin 30. VCC. MMU Pins 6/7 are CAS0 and 21/22 are CAS1 NOTE: MMU Part No. C0100109-001 will not work for 2.5 megs, only 520k, 1 meg, 2 megs, and 4 megs..