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IBM EGA Card Memory Expansion Boards

romanon

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Good job, I suppose that many geeks here welcome this replacement when it will be for good price.
 

mikey99

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Has anyone found a reasonable price on the (24) 4416 memory chips needed for this board ?

I've always wondered if it would be possible to modify the card slightly to use
fewer and cheaper memory chips (ex one bank of 256K chips)

I think it depends on how the memory is configured on the card, just seen as
192K or does the card access each bank separately.
 

modem7

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Has anyone found a reasonable price on the (24) 4416 memory chips needed for this board ?
There is a compatibility table at the bottom of [here].

You could win eBay auction 392596996728 really cheaply. 400 pieces of M5M4416P-15. Current bid: US $3.99. Put aside 24 plus some spares, then use the remainder as Christmas tree decorations (although, probably more appropriate as b-tree decorations).

eBay item 174023679712 (buy-it-now) is for 40 pieces of MB81416. That corresponds to about 50 US cents (plus postage) for each chip, and includes enough spares to last you until the death of the planet due of climate change.
 

mikey99

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Thanks modem7 ! Your eBay search skills are better than mine :)
Picked up one of the 40 chip lots, that's a great price.
 

SunSpotter

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I'd be very interested as well. Also curious how much it cost to have this printed, and what the cost of components were?
 

ab0tj

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I don't mind sharing the design files for this. You can download KiCad and Gerber files here
I'd recommend using the longest pin header you can find for the connector. The most expensive part of the build is the memory itself. I found a decent deal on UTSource, but some patience watching eBay auctions might work as well. The rest of the parts (sockets, capacitors, etc) total less than $20 from Mouser.

I do also have some spare PCBs due to the minimum order quantity from the board house. Maybe $5 plus shipping? I really just need to open an Etsy shop or something these days :D
 

maxtherabbit

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In preparation for this, I pulled out my IBM EGA and stuck it in my 5150. It works, but checkit is showing memory errors between 0A0000h and 0A001Eh. There appear to only be 8 memory ICs on the EGA, but I don't recognize the part numbers. Also do not know which one would correspond to this range. I've attached a photo. Any thoughts?

20200229_162902.jpg
 

modem7

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In preparation for this, I pulled out my IBM EGA and stuck it in my 5150. It works, but checkit is showing memory errors between 0A0000h and 0A001Eh. There appear to only be 8 memory ICs on the EGA, but I don't recognize the part numbers. Also do not know which one would correspond to this range. I've attached a photo. Any thoughts?
See [here].
 

gslick

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There appear to only be 8 memory ICs on the EGA, but I don't recognize the part numbers.
View attachment 59465

inmos databook 1986

www.bitsavers.org/components/inmos/Inmos_Data_Book_1986.pdf

Page 2-15 (Page 82 of the PDF)
IMS2620 High Performance 16Kx4 Dynamic RAM
DESCRIPTION
The IMS2620 16K x 4 bit dynamic RAM is fabricated
with INMOS' advanced Double Poly N-MOS technology
and utilizes advanced circuit techniqes to achieve high
performance, low power and wide operating margins.
Multiplexed addressing and common data I/O allow the
IMS2620 to be packaged in an 18-pin, 300-mil wide
plastic DIP with JEDEC standard Pinout.
 

maxtherabbit

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inmos databook 1986

www.bitsavers.org/components/inmos/Inmos_Data_Book_1986.pdf

Page 2-15 (Page 82 of the PDF)
IMS2620 High Performance 16Kx4 Dynamic RAM
DESCRIPTION
The IMS2620 16K x 4 bit dynamic RAM is fabricated
with INMOS' advanced Double Poly N-MOS technology
and utilizes advanced circuit techniqes to achieve high
performance, low power and wide operating margins.
Multiplexed addressing and common data I/O allow the
IMS2620 to be packaged in an 18-pin, 300-mil wide
plastic DIP with JEDEC standard Pinout.

Excellent, thanks. Good to know they are JEDEC standard 16kx4 DRAMs in case I ever do have an issue with one
 

modem7

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I'll be damned! So there is no problem at all, good thing I didn't break out the desoldering gun yet.
And CheckIt is reported to do something similar for the IBM PS/2 Display Adapter when a monochrome VGA monitor is connected.

Excellent, thanks. Good to know they are JEDEC standard 16kx4 DRAMs in case I ever do have an issue with one
Some compatible chips shown at the bottom of [here].
 

maxtherabbit

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Yeah I already tagged that eBay listing for 40x MB81416s that you linked earlier in the thread. I'll have plenty of spares after building the expansion card :D
 

maxtherabbit

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