Can't say I ever tried to create my own 1MB COAST Module.

I do remember having a couple of Amptron motherboards and finding 512KB COAST Modules, they worked fine.

I think these boards are made by PC Chips Parent company too.

Hah, I wish! 😜

I have an M919, and apart from the whole "no cache" bizzo I quite like it. In fact, I have an Amiga 2000 case here (the mobo died a battery acid death), I was thinking about modding in a PC motherboard, and the M919 was a candidate.

I will watch this thread with interest.

Let us know how that case mod works out, you do realize however that it's sacralige to mod anything PC into an Amiga Case don't you 😜

I think I have a couple of A500's that are stored away as hanger queens for parts and such.

Still have some working ones too.

Like I said, the mobo died acid death, so if I don't do this mod, the case would just go to the tip.

My "in use" Amiga is an A1200HD, complete with still-working 1084S monitor and 4MB Fast-RAM. It's sex. 😁

@BigBodZod

Was it a socket 3, 486 Amptron? It is not a typical COAST module. This 486 M919 uses Asynchronous SRAM, same as the DIP-28 style pieces found on other socketed 486 motherboards. I have tried half a dozen COAST modules, neither work, though they fit in the slot. You need the 'special' M919 module. Pipeline burst modules will not work.

The SRAM chips on the module are the same as that of the skinny DIP-28, but of a different package. 8 pieces, 28 pins each, 1 tag. I may have seen this style of SRAM package still in production recently when searching on newark for a project at work.

I'd be curious if anyone has had any luck with this. I'm putting it on my hobbyist to-do list, though it is of lower priority. What I don't quite understand is that if the motherboard supports 256, 512, 1024 KB cache modules, why aren't there jumper settings for these? Could it be that the BIOS can auto detect the amount of cache? I've never seen that on a 486.

@SquallStrife
You can sometimes fix acid death motherboards by rewiring the PCB traces.

feipoa wrote:

@SquallStrife
You can sometimes fix acid death motherboards by rewiring the PCB traces.

Usually yeah, but this sucker was pretty well gone. The corroded area was a few inches wide, and the legs of the ICs had actually started to rust. It was a real shame.

feipoa wrote:

@BigBodZod […]
Show full quote

@BigBodZod

Was it a socket 3, 486 Amptron? It is not a typical COAST module. This 486 M919 uses Asynchronous SRAM, same as the DIP-28 style pieces found on other socketed 486 motherboards. I have tried half a dozen COAST modules, neither work, though they fit in the slot. You need the 'special' M919 module. Pipeline burst modules will not work.

The SRAM chips on the module are the same as that of the skinny DIP-28, but of a different package. 8 pieces, 28 pins each, 1 tag. I may have seen this style of SRAM package still in production recently when searching on newark for a project at work.

I'd be curious if anyone has had any luck with this. I'm putting it on my hobbyist to-do list, though it is of lower priority. What I don't quite understand is that if the motherboard supports 256, 512, 1024 KB cache modules, why aren't there jumper settings for these? Could it be that the BIOS can auto detect the amount of cache? I've never seen that on a 486.

@SquallStrife
You can sometimes fix acid death motherboards by rewiring the PCB traces.

Since I no longer have the board nor COAST modules, I can't really recall for sure. I just remember purchasing it at the same time as the motherboard from the same vendor, paid a pretty penny for it too.

I wonder if it was a BIOS or hardware specialty module ?!?

I will check it out and see if I can locate that model, I just really remember the Red and White colored box it came in.

EDIT:

Found it, it was a later mobo, I remember that it came bundled with the Cyrix 6x86-166/200 or 233 and the Intel 430VX chipset, a Socket 7 board and it was an Asynchronous COAST module too.

http://www.motherboards.org/mobot/motherboard … mptron/PM-9000/

feipoa wrote:

Anyone with a PC Chips M919 v3.2 or v3.4 try to upgrade the cache on the COAST-like SRAM cache module? The manual claims that it will accept up to 1024 KB Asyn SRAM, but only the 256KB modules were ever produced from what I can tell.

This project would entail desoldering the current 9 chips, sourcing new ones, and soldering the new ones on.

I'm trying to source one myself but all the information I am finding on them says that they are NOT the same as a COAST module. They look like a COAST module and have the same number of pins, but they are not electrically compatible. Plugging a COAST module in could damage the motherboard or PSU. You need modules that are clearly marked for use with the M919 only. Most of the modules that were sold were also purchased at the same time as the motherboard not loose, so finding one separate from the motherboard it came with is not going to be easy.

Correct, it is not a COAST, it is COAST-like.

There is nothing fancy about the module, it contains SRAM pieces, a few capacitors, and a few resistors. The project would be to desoldier an existing M919 module, known to work, that has 256 KB SRAM and replace the 9 SRAM pieces with 1024Kbit SRAM pieces.

feipoa wrote:

Correct, it is not a COAST, it is COAST-like.

There is nothing fancy about the module, it contains SRAM pieces, a few capacitors, and a few resistors. The project would be to desoldier an existing M919 module, known to work, that has 256 KB SRAM and replace the 9 SRAM pieces with 1024Kbit SRAM pieces.

The 1024kb SRAM chips have more metal legs though, you might be out of luck

The skinny DIP-32 1024's have more legs, 4 more, but I am not sure about this other SRAM package style that is on the module. But you are right, I've never seen a 28-pin DIP style 1024K form factor. Let's hope this doesn't hold true of the other package.

To follow-up on this, and to scratch an item off the list, I couldn't find any 28-pin 512Kbit or 1024Kbit SRAM pieces at 5V, SOJ-28. So if you want more cache in your M919, you'd have to send out a custom PCB drawing for the DIP-32 package to a company that does PCB printing.

On the other hand, the cache that is in existing 256 KB modules still exists new for purchase, but you'd still have to send out a custom PCB.

Otherwise, if you want to upgrade your existing M919 from 15 ns cache to 12 ns cache, options are available for purchase, but it would require a lot of soldering for marginal to zero improvement.

ISSI
IS61C256AL-12JLI
$1.36 each x 9 = $12.24

ALLIANCE
AS7C256A-12JIN
$2.65 each x 9 = $23.85

Since its on the topic, look at this link for a good laugh, a PC Chips M919 V3.X, not even 3.4 B/F (latest), selling on eBay for $349.99! Its not even from wiredforservice this time.

He must have seen your post, because he's just reduced the price!

retro games 100 wrote:

He must have seen your post, because he's just reduced the price!

I wouldn't pay that much for it even if it came with the cache module.

retro games 100 wrote:

He must have seen your post, because he's just reduced the price!

Hmmm....is that some oxidized contacts I see over there in that 3rd ISA slot?¿?.....(waits for price to collapse again 😁)