1 megabit x 4 DRAM chips for SupraDrive 500xp - where to get them?

[Frimann]

Hi all!

I recently bought a SupraDrive 500xp expansion for my A500. I've fitted an old SCSI HDD in the box and it works fine. I would like to make use of the 16 DRAM slots in the box as well, but I can't find the appropriate RAM-chips anywhere. So I have to ask: Does anyone know where to find "1 megabit x 4 DRAM chips (4 megabit) in a 300mil DIP package"?

If any of you have had any experiences, good or bad, with the SupraDrive 500xp in general, please share them as well =)

[Zetr0]

@Frimann

hello there,

Welcome to the EAB, there plenty of mischief to get up to around here , so once we have this problem sorted, take an opportuinity to enjoy the honey coated retroliciousness that that this board offers

Now, Looking at the picture here http://amiga.resource.cx/photos/supra500 they look like 18 pin DIPS,

now off the top of my head, the best place to get them would be an old graphics card (probably ISA) from the pc. (rob them using a soldering iron), but to make sure of this can you post the detail that written on the chip as i may have some.

[Frimann]

@Zetr0

Thanks for the warm and fuzzy welcome =)

The interior of my 500xp looks somewhat different from the one depicted on Amiga Hardware Database. I've shot these photos:





It looks like 20-pin slots to me, but I'm no expert. Does this make a difference?

[Zetr0]

@Frimann

Ahaaaaa!

oh, i tihnk you will like this....

before i state for the record just make sure by asking some one else.

you should be able to populate this using the 20pin memory chips from A500 0.5mb upgrades (ones that have 4 chips)... these you can get for around £3-6 or cheaper on fleabay

I will check what i have in my cabinet... i may have about 2mb you can have

but like i say, best to double check.

[Zetr0]

BTW....

thanks muchly for the hardware pr0n

[Frimann]

#Zetr0

NP... more will follow when the thing is populated =D

I've found several variations of the A500 0.5mb expansion, but none with only four chips:

• Ebay, 16 chips
  
  
• Ebay, 5 chips (maybe the horizontal chip isn't a ram chip after all?)

• Amigakit, 8 chips

I can't find any proof if these chips work with the 500xp or not, but I'll give it a shot. Now, which ram expansion to buy?

[Zetr0]

@Frimann

okies

• link 1
  Alas no, 16pin dips
  
  512k/16 = 32k arranged as 4bit
  
• link 2
  Aha! this 0.5mb ram over 4 chips (the other one is a logic chip)
  
  512k/4 = 128kb arranged as 4bit words (perfect)
  
• link 3
  its a pity, although these are 20pin DIP there two small in chip size
  
  512k/8 = 64k arranged as 4 bit words

so from the list link 2 is appropriate , however although i am sure it will work, i do suggest that before you attempt it just check with some one else

oh.... you will have to de-solder these from the board.... i also need to check my cabinet... just been so busy for a bank holiday lol

[Frimann]

I chose the four chip ram expansion, but could only get my hands on a single one though. I'll return when I have tried it out =)

[Zetr0]

@Frimann

I have discovered four of these chips (0.5mb), you can have 'em for say £5 which will include postage to Denmark ?

[Frimann]

@Zetr0

That's great! I'm very interested =)

I'll double that for your trouble. If you send your account information to sf@lite.dk I'll make the transfer asap and send a delivery adress back to you.

[Zetr0]

@Frimann

indeedy, when get home i shall send the details

[Frimann]

I have 20 chips at the moment; 12 distributed across three 0.5MB boards and 8 on a single 1.0MB board. To my disarray however, I discovered that the battery on my old 1.0MB expansion had leaked, so I've decided not to desolder the 8 chips from the new one and instead use it as replacement.

Did that make any sense at all?

What it all comes down to, is that I only have 12 chips I can put to use in the SupraDrive 500XP, so I'm still interested in your chips Zetr0. You never sent me any further details though?

By the way - I've removed four 256KB 20-pin chips from my busted 1.0MB expansion if anyone is interested. My SupraDrive 500xp only eats the 128KB ones.

[Zetr0]

@Frimann

sorry my friend, i completely forgot... posting details now...

[Zetr0]

Here are the chips I am about to seen way off into the yonder on Monday


I just love hardware pr0n... dont you you?


The TMS chips are 10ns and the NEC are 70ns, according to the specs of the SupraDrive, as long as there 120ns or faster (lower) then there fine

yes these were reworked from a dead A501 and some i had floating around

[Zetr0]

@Frimann

just 8 more my friend and you have a full deck of 2MB to have fun with.



Have a look on www.AmiBay.com and request to "Recycle Bin" to one of the mods, 0.5mb A501's pop up there from time to time

[Frimann]

@Zetr0

Oh my! Desoldered and all! You're the man

I already got two 0.5MB expansions awaiting my soldering iron, which I will get around to sometime next week. Hardware pr0n will follow in due measure

[Frimann]

Behold the might of my recently populated 500XP and cringe in fear!







It works like a charm, but I've experienced something quite weird. Just for the fun of it, I installed four 256kb chips along with the twelve 128kb ones, and now Workbench suddenly detects 4MB of extra RAM instead of 2MB! How is this possible? It really makes no sense

Screen from WB (512kb of the total extra memory comes from a regular RAM expansion):





The 256mb chips has the following information printed on them:

M5M44256BP
415GE01 -7

[Zetr0]

@Frimann

AWESOME!!!! glad you got this bad boy up and running... and whats even more awesome is the fact the logic can string up 4bit 256k chips!!!

In fact i wonder if this could indeed string up 8MB total?

The 12 128kb chips provide 1.5mb of ram and the other obviously 1mb, I am thinking that the problem is that it could well be that the logic only probes the first chip and then strings the rest up according to that. what do you get when the 1MB is removed?

this really is interesting and an undocumented feature of this card ! well played..

now the trick would be to see if it can write to a full 4/8MB hmmm i may have some 256kb chips... i will hunt later for you

Glad the chips got through!!!

and THANK YOU for the pics its great to see

[Frimann]

@Zetr0

That actually makes a lot of sense. I should probably remove the 256k chips so I don't destroy anything

Can you get any sense out of this passage from the manual?

For 2, 4, or 8MB RAM configurations, the 500XP is designed to accept - directly on the board - 1 Mbit x 4 DRAM chips (4 megabit) in a 300 mil DIP package. At the time this manual was written, however, 1Mbit x 4 DRAMs were mainly available in the ZIP package. These instuctions are provided for a time when these DIP chips become commonly available.

The DIP RAM used for 2MB, 4MB, or 8MB configurations must be 1 megabit x 4 DRAM (DIP) chips, 120 nanosexonds or faster. For 2MB, you'll need 4 chips; for 4MB, you'll need 8 chips; and for 8MB, you'll need 16 chips.

- I kind of asumed that these chips never became "commonly available" xD

[Zetr0]

Thats just awesome, when i get some time i shall dig around and see what i have , should i find anything, you can have it for postage if you want