ees@antique.UUCP (Gene Sampieri) (01/11/89)
I am trying to upgrade a Apple II GS memory expansion card from the normal 256k to a full 1 meg (for a machine total of 1.25). The chips on the board are TI TMS4256, and the ones I am using are NEC 41256 or Toshiba 41256. According to the data books these are identical. All are 150ns devices. The system will not boot up when they are installed and the jumpers in place. The control panel willl come up properly and does indicate that there is 1.25 meg total memory. I suspect only the jumpers are being read in this case and the memory is not being tested. Am I doing anything wrong?? Is there something the books that come with the machine (system and memory books) are not telling me?? HELP Gene Sampieri AT&T Bell Labs Holmdel N.J. vax135!ees
rkh@mtune.ATT.COM (Robert Halloran) (01/12/89)
In article <2501@antique.UUCP> ees@antique.UUCP (Gene Sampieri) writes: >I am trying to upgrade a Apple II GS memory expansion card from the normal >256k to a full 1 meg (for a machine total of 1.25). The chips on the board >are TI TMS4256, and the ones I am using are NEC 41256 or Toshiba 41256. Looks as if the canonical list of RAS-before-CAS DRAMs needs to be posted again. Could someone with better memory/archives than me post it again? I know it saved me MUCH grief when I upgraded; it looks as if the next wave of owners needs that help again. Bob Halloran ========================================================================= UUCP: att!mtune!rkh Internet: rkh@mtune.ATT.COM USPS: 17 Lakeland Dr, Port Monmouth NJ 07758 DDD: 201-495-6621 eve ET Disclaimer: If you think AT&T would have ME as a spokesman, you're crazed. Quote: "May: In Baton Rouge, the Rev. Jimmy Swaggart, announcing that he has been forgiven by the Lord, returns to his pulpit, where he receives a warm reception from 300 billion locusts." - Dave Barry's 1988 Year-In-Review
ALBRO@NIEHS.BITNET (01/13/89)
Suppliers of CAS before RAS 256K memory chips for the IIgs: Hitachi HM50256-15 Mitsubishi M5M4256P-15 Fujitsu MB81256-15 OKI MSM41256A-15AS/RS Micron Technologies MT1259-15 Samsung KM41257-15 Toshiba TMM41257-15 Texas Instruments TMS4256-15 but you should still SPECIFY CAS before RAS when you order. This list is from AE, so there may be some additional sources.
Ronald_Sampson.HENR801c@XEROX.COM (01/18/89)
Gene, I have found a number of things about the Apple II GS and the memory expansion board. 1. the 41256 -150 chips must have CAS before RAS during the refresh cycle. This means the Column Address Strobe is refreshed before the Row Address Strobe. 2. The NEC chips, though designed to be CAS before RAS, had a batch that were manufactured incorrectly. These chips were manufactured in the UK and Japan unforturnately I don't have the information that can cull out the bad ones made at these locations. However your local service center should have the information. Finally, I am having the same problem. I am using Samsung chips designated KM41256AP 15, KOREA 832. I called Apple and they said they had approved these chips along with the KM41257 for use in Apple products. I called Samsung and these chips also have the CAS before RAS function. However the chips still don't work in the computer. My assumption is that Samsung has manufactured a defective batch. That is the situation as it stands today. ronald