How to id Mac Portable ram- Now the M5126 Project

[Maconthemove]

There are two Apple numbers on it.

820-0662-A 820-0662-01

On the front there is two rows of six PSRAM and the same on the back.

24 chips total. 1990

Could this be a 3 or 4 meg ram card?

 

[equill]

May I suspect, from your signature, that you are writing about PB 1xx RAM? Or are you writing literally about The Portable/Luggable/Herniating?

If your card were for a PB 1xx, with six rows of two on each side, it would be 12MB, which, with the on-board RAM would result in 16MB total, which is 2MB more than the max. of 14MB.

If, however, the card is trapezoid in shape, it is An Horse of A Different Colour. Apple Service Guide, Macintosh Computers Vol. 1 (1993) mentions three expansion RAM cards for the Portable: 1MB PSRAM 661-0614; 3MB PSRAM 661-0613; and 1MB SRAM 661-0480. However, Portable cards have room for two rows of eight chips on each side, rather than six only. Perhaps yours has two vacant pads in each row? One could then hypothesize that you have a 3MB card. I have just looked at three cards, all marked 630-4176 and ©1989, and using Sony (CXK58257M-10LL) or Mitsubishi (HM62256LFP-10T) chips. They have what I presume to be their standard ration of 32 x 8-bit 100ns chips (as on the logic board) for 1MB.

Apple's (Service Source) Memory Guide, January 2001, further mentions expansion cards (presumably third-party) of 1-8MB SRAM as being supported by the Portable, ie up to 9MB total. See whether you can diagnose your chips at Chipmunk, although most of what he lists is DRAM rather than SRAM.

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[Maconthemove]

The computer is a Mac Portable w/

backlite. There is no way that 8 chips could be put across on this card. The chips are Hitachi 658128ALFP-10. The card is 1990

 

[Maconthemove]

Took apart the portable and put it together. It now boots up. The battery is dead,the 9volt battery is dead, the hard drive is dead and the backlite is dead.

The portable has 4megs and the screen works(except for the backlite). There may be a card missing from the rom slot.

Going to pull it apart, and do a really good inspection of the motherboard.

 

[equill]

If those 4MB show with your question card in place, 3MB it must be. Your PSRAM card is shown in the Apple Service Guide, Macintosh Computers Vol. 1 (1993) on p127. It is quite distinctive, in that the rows of six staggered chips follow the oblique upper edge of the card. The 1MB PSRAM card has only four staggered chips. Yours is evidently the later Portable, and you will find that the RAM expansion slot is keyed so that you do not try to insert an SRAM card (rows of eight chips, parallel to the bottom edge of the card), which is incompatible with your Mac.

You need have no concern about the apparent absence of a ROM SIMM. The portable would not have booted without the two ROM chips on the logic board (between the modem slot and the eight soldered-in PSRAM chips). The ROM slot is thus one of the several instances wherein Apple provided a slot 'in case ...' You are more likely to have trouble then if the ROM select jumper is not on its header (near the FDD connectors, and sometimes replaced by a DIP switch).

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[Maconthemove]

Yes there is a cap on the pins