info-mac@uw-beaver (12/27/84)
From: <OTHB@SRI-KL.ARPA> I just picked up a copy of Doctor Dobbs (Jan 84 issue) and it does indeed have instructions and pictures showing how to do your own Mac upgrade. They claim all the parts (incliding 16 256K chips) can be had for under $300, but of the memory vendors listed in the article with 800 numbers, none of them had chips for $15 ea (some said they didn't have them at all). My questions? - Has anyone tried this upgrade yet? Did it go smoothly? - Where is the cheapest place to get 256K bit DRAMS? -Jon Spear -------
info-mac@uw-beaver (12/31/84)
From: dlc@LANL (Dale Carstensen) > - Has anyone tried this upgrade yet? Did it go smoothly? Yes. Mostly. The first hard part was getting a Torx T-15 screwdriver with a long enough shaft. I took a Master Mechanic magnetic-interchangeable-tip model, modified the T-15 tip with part of a magnetic extender and part of a 1/4-inch bolt with a welder to make the T-15 tip about 4 inches long. The second hard part was discovering (I had read it earlier, I'm sure, but forgotten) the fifth screw is in the battery case. The third hard part was getting a cutter that will go between the pins on the 64K memory chips. I did some grinding on a cutter I had, but good precision diagonal cutters would be better. I had some strip socket pins I put in, so I was able to get by without taking all the old pins out, but if I did it again, I would do it the DDJ way. I also had the A.P.P.L.E. instuctions, and the logic is the same, but the DDJ method of modifying a socket to piggy-back the current 74AS253 is better, I believe (my opinion). I also installed a slide switch over the "tosh" silk- screening by the reset switch so I can switch back to 128K (good thing, the September Softworks C doesn't work with 512K). It's an SPST switch with common to E3-2, 128K side to E3-1, and 512K side to the 47K ohm resistor to F3-7. A 74LS253 worked where a 74AS253 or 74F253 was recommended, by the way. There is an error in the DDJ article, but you will notice it because it is inconsistent with the illustrations -- p. 20, first bullet after (9), it says "bend out all the pins except 2, 7, 14, and 16." The "7" should be "8". This single article saved me about 15 years' worth of DDJ subscription cost! Of course, Apple is partly to blame, and I don't get MacDraw and MacProject. If they are as buggy as MacWrite and MacPaint, I'm not sure I'd want them. > - Where is the cheapest place to get 256K bit DRAMS? Microprocessors Unlimited, 24000 S. Peoria Av., Beggs OK 74421 (Tulsa suburb) (918) 267-4961 open 6 1/2 days a week They gave me terrific service. A sheet included with the shipment stated they would soon add 3% to credit card orders, with an alternative of the customer sending a check the same day the order is made, also providing a credit card, and mu P infinity (don't have Greek letters or lazy 8 in ASCII) would turn in the credit card charge with the 3% added if the check didn't show up in 7 days. They prefer telephone orders to mail, so they can discuss alternate vendors if your preference is out of stock. About a month ago 150 ns. 256K RAMs were $14.47, when I ordered two weeks ago, they were back up to $14.99 (Fujitsu). 120 ns. and Hitachi were a little higher. I don't think they stock the 74AS253 necessary for the Rev. C board, but you could ask. Note the Rev. F board does not require any chip, and the modification description is on p. 4 of the January DDJ.