29.91666666667k memory chips?!

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iamdigitalman's picture
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29.91666666667k memory chips?!

I have been cobbling together a pretty nice ultimate IIgs over the last few months. Rom 3, Woz case, memory board with all populated chips, 3.5" and 5.25" drives, 2 hard drives (need a SCSI card for that, though I have the cables, and software, grr), and original keyboard and mouse.

In my workings, I pulled a fully populated Apple Memory Expansion Board from one of my ROM 01 machines. I got curious as to how large the add on chips are on the board.

I booted the machine from the 6.0.1 floppy, went to "about this Apple IIgs". Under total memory, it read 2126kb of RAM.
The machine s a ROM 3 with 1MB (actually 1.125mb or 1152kb)
2126 less 1152 is 974
there is 256kb in 8x32kb built on to the RAM expander.
974 less 256 is 718.
this leaves the rest in the add on RAM. There are 24 slots, and all 24 are populated.
718 divided by 24 is 29.91666666667.

How is this possible? I thought RAm chips go by 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, etc increments?

or is this kilobyte versus kilobit?

not that it effects operation of my IIgs, just something that snags my curiosity.

btw, all the add on chips are made in USA. If anyone wants I can give the numbers off the chips. 5 have the american flag silkscreened on (very nice touch), and the other 19 simply say "USA" on them.

-digital Wink