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ITXPlus: A ITX Sized Macintosh Plus Logicboard Reproduction

Builder68 said:
An Octopart search for AS4C1M16E5-60JC shows it to be abundantly available brand new from several distributors. I bought mine on Aliexpress (brand new), but they can also be found on Amazon. Indeed, this chip could replace the onboard memory, thereby updating the LB replicas for the LC and Plus models. Could it be just leftover stock, perhaps?

AS4C1M16E5-60JC ALLIANCE Original supply, US $ 1.63-1.96 , Memory, [ALLIANCE] Alliance Semiconductor Corporation - SeekIC.com

AS4C1M16E5-60JC ALLIANCE, AS4C1M16E5-60JC Selling Leads, Price: 1.63-1.96 USD, MFG: [ALLIANCE] Alliance Semiconductor Corporation, Category: Memory, Summary: AS4C1M16E5-60JC, CMOS Dynamic Random Access Memory, -1.0V to 7.0V, 50mA, 1W, SOJ
kwlhk.en.seekic.com

BTW, this chip is the same used by Garrett’s Workshop in its 3MB RAM expansion board for the Classic.
Click to expand...
Those are 16MBit chips (hence, I guess AS4C1M16E5-60JC), meaning 1MB x 16-bit. They're 2MB each. So, 2x DIY SIMMs with 2 chips each would provide another 8MB of DRAM, taking my LC II to 10MB (assuming fixing it is as easy as a recap?).
 
Port PCB's arrived (which I totally hadn't forgotten to order....) and the board has been fully tested and works just fine :)
IMG_4396.jpg

I guess now I need to tidy up the schematic, after all I did leave this note in it :ROFLMAO:
1749333658915.png
 
When these are ready count me in for buying a couple off you (if you're still doing that). Have some ideas for this.

Great work!
 
For anyone interested, I've made a daughterboard for the ITXPlus that allows the addition of an IWM or SWIM chip in DIP-28 form. It mates with the 2x12 header on the ITXPlus and provides a pair of floppy headers, ready for your Floppy Emu, TashTwenty, or even actual floppy drive! Also made an adapter board (pictured below) in case you have a SWIM in PLCC-44 form that you want to adapt to DIP-28.

1765635590485.png

The .brd files and gerbers (see releases) are available on Github:

github.com

GitHub - lampmerchant/misc-mac-pcbs: Miscellaneous PCBs for Macintosh retrocomputing.

Miscellaneous PCBs for Macintosh retrocomputing. Contribute to lampmerchant/misc-mac-pcbs development by creating an account on GitHub.
github.com github.com
 
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