ITXPlus: A ITX Sized Macintosh Plus Logicboard Reproduction

[mg.man]

V1.1 boards have arrived and passed a basic power on test with no bodges

 

[Snial]

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.

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?).

 

[cheesestraws]

This is great stuff, Max.

 

[max1zzz]

Port PCB's arrived (which I totally hadn't forgotten to order....) and the board has been fully tested and works just fine


I guess now I need to tidy up the schematic, after all I did leave this note in it

 

[ldicker83]

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!

 

[mst3k]

Ditto what he said...
When/if you intend to sell, please add my name to the list.
Thanks!

 

[max1zzz]

I will indeed have a few for sale soon

 

[ldicker83]

Nice, looking forward to it!

 

[DrewyNucci]

I will indeed have a few for sale soon

Shut up and take my money! Lol!! Amazing work! Congrats on doing something truly spectacular!!! Count me in for whenever there is something available!!

 

[max1zzz]

Things have been moving a little slowly lately but I'm finally getting things sorted out
For those that wish to purchase boards: https://68kmla.org/bb/index.php?threads/fs-itxplus-pcbs-kits-and-assembled-boards.50166/
And for those that wish to build their own from scratch: https://github.com/max234252/ITXPlus

 

[Tashtari]

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.



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

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

 

[defor]

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.

View attachment 93276

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

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

Just got my ITXPlus board in today (really excited, but probably won't have time to fire it up for a few weeks as I'm moving)... regarding the SWIM adapter.. any thoughts to making it in a formfactor such that it can just plug over top of the motherboard header and then exposes the floppy plug upwards or forwards?

 

[Tashtari]

any thoughts to making it in a formfactor such that it can just plug over top of the motherboard header and then exposes the floppy plug upwards or forwards?

I think that's what this board does, unless by "the floppy plug", you mean a 19-pin D-sub. That's what I would have reached for at first, but as far as I know they're unobtanium...

 

[defor]

i meant like the board would have to be designed with the male plugs on opposite sides of the board so one can plug into the board and the other one wouldn't be sandwiched in the middle...

 

[defor]

...Also IIRC BMOW had a whole lot of 19-pins made a while back and was looking to unload some... MAYBE?