upgrading A500 to 8MB fast ram

[kamiga]

I have an A500 with a VXL-30 accelerator with 2mb of 32-bit fast ram.  It also has the 512K chip expansion module, and a DataFlyer 500 IDE controller on the expansion port.

Finding 1m x 4-bit memory chips has been a real PITA, but I finally found a source for them.  The problem is that the memory chips are 26/20-SOJ.  They are surface mount, and have a weird package, where the 20-pins are spread out across 20-legs, but with center 6 pins not being used at all.  In any event, the accelerator's ram card has 20-pin DIP sockets.

Soooo, I found an adapter, which of course would require me to solder each IC onto the adapter.

http://www.accutekmicro.com/pdf/16%5F24%5FPin%5FDip%5FAdapters%2Epdf

namely part number AK20D300-SOJ.

AccutekMicro wants $5 each.  There are 16 chips, so $80+shipping minimum.


I'll spend the money if necessary but don't want to do so frivolously.

Is there any easier way to expand my A500 to 8mb of 32-bit fast ram given my configuration?

I seem to remember 15 years ago when I bought the Dataflyer 500, it had a memory option too, which somehow conflicted with my accelerator card --- I ended up returning the dataflyer ram and getting the accelerator card's ram.

I really don't mind soldering the memory chips onto the adapters --- I've got a nice ESD digital-controlled solder station, and I would like the practice with surface mount stuff.  So don't consider the "work" an issue.....

Thanks

Keith

[rkauer]

 I think is better to source those regular 514400-60ns DIP chips instead.

 You can find them in old ISA video cards, like Trident and others. Also findable NOS in several electronic sellers around the 'net.;-)

[kamiga]

rkauer wrote:
 I think is better to source those regular 514400-60ns DIP chips instead.

Well heck yeah.  But I can't find those chips any place.  And I've emailed and posted and searched and searched.

 You can find them in old ISA video cards, like Trident and others.

Can you be more specific?  Any specific make/model of Trident cards? Would I be looking for like 4mb and 8mb cards?  How would I narrow them down enough to know they use 514400 or similar?

 Also findable NOS in several electronic sellers around the 'net.;-)

Like who?  I've checked a variety of different places. Newark. Digi-key. Mouser. Jameco. Jdr. Memory ten. and others.

The only places that _claim_ to have them are the "chips4less4u.com" places that have large minimum orders -- and many of them are pulls.

Thanks
Keith

[rkauer]

 For your information: those chips are (electrically) pretty identical to the ZIP versions (used in a variety of old Amiga expansions) with the exact same code, albeit the different form factor.

 I don't remember the exact VGA card name right now, but I'm sure someone will point it.

 Those cards are from the 286/386 era, so expect to find them in 256 and 512kb VGA ISA cards, in peecee junkyards.

[kamiga]

I managed to get ahold of some SMT chips that are electrically compatible with the the DIPs too.

They are IBM 014400MT1D-70's.

But adapting them will be expensive and time-consuming, as mentioned.

256 or 512kb?  Assume I'm bad at math.  How many ISA video cards would I need to get to 8mb??

Thanks

Keith

[rkauer]

 Each chip is 256k x 4bits (444256 or 514256), so expect to use 8 chips for a humble Mb!

[kamiga]

rkauer wrote:
 Each chip is 256k x 4bits (444256 or 514256), so expect to use 8 chips for a humble Mb!

You mean each chip is 1M x 4-bits, right?  Those are the ones I need.  16 * 4megabit chips = 64 megabits = 8mb.  The 14400's.

I currently have the 514256's, 16 * 1megabit(256k * 4) chips = 16 megabits = 2mb.

Now do the video cards you are talking about have the 14400's or the i-already-have smaller 514256's?

I'm confused.

Keith

[Chain]

cross reference doc
http://www.hypertechnologyinc.com/pdf/crossref.pdf

$2.50 each http://cgi.ebay.com/4C4001-MT4C4001JDJ-6-MT4C4001JDJ-MT4C4001-DRAM_W0QQitemZ140070812144QQihZ004QQcategoryZ4663QQrdZ1QQssPageNameZWD1VQQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247

[kamiga]

Thanks for the post, but I don't believe those are DIPs.

Even if they are DIPs, the form is wrong.

See http://www.amiga-hardware.com/download_photos/vxl30_4_big.jpg

Notice there is no gap between the center pins.  All 10 pins in a row on each side, with equal spacing.  Probably .1 on center.

Thanks

Keith

[rkauer]

kamiga wrote:

You mean each chip is 1M x 4-bits, right?  Those are the ones I need.  16 * 4megabit chips = 64 megabits = 8mb.  The 14400's.

I currently have the 514256's, 16 * 1megabit(256k * 4) chips = 16 megabits = 2mb.

Now do the video cards you are talking about have the 14400's or the i-already-have smaller 514256's?

I'm confused.

Keith

 Look for old peecee 286s too, they use the chips also.

 For better explanation: those 514256 and 44256 are 256k x 4bits (= 8 chips to achieve 1Mb). The 514400 is 1Mbit x 4bits (=2 chips per Mb).

 Look for VGA boards from Orchid, Trident and some Vesa boards too. Prefer those who have 60ns chips on it.