Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!ncar!oddjob!gargoyle!ddsw1!karl From: karl@ddsw1.UUCP (Karl Denninger) Newsgroups: comp.sys.tandy Subject: Re: Model 4P with bad RAM Summary: Tandy is WIERD Message-ID: <1053@ddsw1.UUCP> Date: 10 May 88 14:13:11 GMT References: <4WUwM8y00XcSQ5LUE3@andrew.cmu.edu> Reply-To: karl@ddsw1.UUCP (Karl Denninger) Organization: Macro Computer Solutions, Inc., Mundelein, IL Lines: 45 In article <4WUwM8y00XcSQ5LUE3@andrew.cmu.edu> dp1g+@andrew.cmu.edu (Demetri Patukas) writes: > >I have a Model 4P with a bad ram chip. > >After swapping some chips around I found the offending chip. > >So I thought, "no problem, just stick in a 4164 and off we go" > >Didn't work. > >So... can anyone tell me what the story is on the ram chips in the 4P? >They have the number "8040665" stamped on them with both Motorola and >Tandy logos. I have a friend who used to do upgrades on these who >claims that these should be the same as 4164's, but when I used a 4164 >it always read zero in that bit position. Are these special Tandy >rams? Can I maybe bend some pins and use a 4164? You can use a 4164 IF AND ONLY IF the refesh cycle spec is right. The scoop is this -- some chips require 128 "refresh" cycles, and some require "256". The latter chips do NOT work in Model IVs. This includes nearly ALL of the American parts -- only the Jap stuff works at all. An example of "Known good": Oki 4164 Texas Instruments 4164's, for example, while having the same part number (4164) do not work at all. >Also, although my machine has sockets for a second set of 64K, my >friend tells me that I will need a new PAL chip to get the machine to >recognize it. Where can I get the new PAL? How much should I expect >to pay? If your Model IV is an older model (which tube, non-clustered arrows) then you need the PAL for the second 64K. Good luck finding one now-a-days... If it's a new one (green w/cluster) then you only need to solder a wire or two and put in the chips. Somewhere I may still have the info around -- we used to do these on a regular basis. --- Karl Denninger | Data: +1 312 566-8912 Macro Computer Solutions, Inc. | Voice: +1 312 566-8910 ...ihnp4!ddsw1!karl | "Quality solutions for work or play"