FSA1ST Memory Expansion

By Yngwie

Rookie (19)

Yngwie's picture

05-07-2007, 01:03

Today I've gotten my hands on a Panasonic FS-A1ST. Wasn't sure whether it would run, but was glad to see it worked perfectly. Diskdrive, slots, keyboard, it's all fine. Now for the strange part. When I start the ST it tells me it has 512KB main ram. I was surprised since the previous owner never used it much and thought it was the basic machine. I decided to open it up to see whether it was really 512KB or not. Turns out there are two 44C256 IC's in the previous empty slots (in an IC socket even, so I can take them out if I ever need to.)

According the the http://www.hansotten.com/msxdiy.html website there need to be several modifications to upgrade the ST's memory. A few capacitors and a few resistors. The 2 resistors on R55 and R41 are soldered on. BUT, the C138 and C140 SMD capacitors are not. I didn't check the R229 SMD resistor yet because it's on the bottom of the PCB (and it's getting rather late) Since it's SMD I have a feelings that this resistor is missing also.

Can anyone tell me if this can or will give me problems? All the tests I have done ran without problems, games, megademos, everyone ran perfectly sofar. But because I don't want the ST to stop working I would like to know for sure whether or not this is a potentional problem :) I don't have equipment to solder SMD, so would like to know if it's worth the trouble to have it fixed.

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By Yngwie

Rookie (19)

Yngwie's picture

05-07-2007, 10:38

In the meantime I've gottan a reaction from Hans Otten (see the link in my previous post). He has come across several ST's without those parts soldered on the PCB which work perfectly. His advice: leave it the way it is if there are no problems. So if anyone else comes across this issue, there ya go Wink

By nikodr

Paladin (748)

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05-07-2007, 12:39

Well with 512 kbytes you can play 99% of games,symbos works great with it,you can have many applications open.

I do not know if it is true,but maybe you could get an external memory mapper and an expansion of 4 mbytes and use it as external cartridge?I got one and i am very happy.

Since you will have dos 2 and greater i think the bigger memory mapper is always activated first.

But i am not sure about turbo-r.Maybe some more experianced msx user can inform us?

By Yngwie

Rookie (19)

Yngwie's picture

05-07-2007, 13:31

But i am not sure about turbo-r.Maybe some more experianced msx user can inform us?

The advantages of 512KB are clear, am rather experienced enough to know that already (or should just substitute experienced with old Tongue Smile I just wasn't sure whether the absence of the SMD parts would affect stability or reliability of an ST (before I owned a GT which naturally already has 512KB) Smile

By jltursan

Prophet (2619)

jltursan's picture

05-07-2007, 14:08

So, if I've understood, one can try to upgrade the ST memory just filling sockets IC31 and IC33 with 44C256's?, could it be harmful for the machine to try this without adding the rest of the components?.
I found very strange that the upgrade works on some machines and not on others...Question

By Yngwie

Rookie (19)

Yngwie's picture

05-07-2007, 14:30

So, if I've understood, one can try to upgrade the ST memory just filling sockets IC31 and IC33 with 44C256's?, could it be harmful for the machine to try this without adding the rest of the components?.
I found very strange that the upgrade works on some machines and not on others...Question

Well the 2 regular, non-smd resistors were soldered on the mainboard. More than likely the person that made the modification didn't have the tools or confidence to add the SMD components. And on this ST it works perfectly sofar Smile

By nikodr

Paladin (748)

nikodr's picture

05-07-2007, 14:30

Personally i would never ever do anything to such a machine unless i was very experianced with soldering skills (which i am not).If something goes wrong,it will be very difficult to fix.And turbo-r machines are rather rare.So don't risk it unless you know what you are doing Smile

By Yngwie

Rookie (19)

Yngwie's picture

05-07-2007, 15:03

Well more than likely this modification has been done quite some time ago (when they were still being imported from Japan and not so rare) The person I bought it from hadn't used it in many years. I have a lot of experience soldering and this wouldn't be a problem if I had SMD equipment at home, but I don't Smile The memory chips themselves are the old ones, no SMD, so plenty of room to solder with a regular solder iron Smile

By SaebaMSX

Hero (533)

SaebaMSX's picture

05-07-2007, 16:17

Hi Malmsteen!

My A1ST has 512KB and the chips are not SMD either, no problems so far. I know who upgraded it for me so it seems safe, since he decided to use normal resistors because soldering SMD ones are not "so easy" without the necessary equipment, as you already said.

I hope it helps you. Smile

By CrazyBoss

Master (210)

CrazyBoss's picture

21-07-2007, 19:10

i had a a1st too, actually i still have it some where
in parts, the diskdrive is missing we tried to put a pc-drive inside but it dont work Sad
the keyboard is bad too, cause the soft-silver connections are broken (keyboard plate/pad)
anyway this turbo-r was maybe the first one to hit european soil. It belong to Henrik Gilvad, when he bought a GT turbo-r i bought his A1ST.

He upgraded it with more video memory 192kb i think totaly.

And it have 512 also but 256 are standard. I think it was impossible to build in more than 512kb since Henrik never did that (it might have been impossible cause that man could do anything to a MSX).

I think we spoke about back then to try to discconnect the internal mapper and memory and build a new mapper with more memory, as he did in the SVI738. I have seen SVI738 with 1mb memory, but i think there might be 4mb versions too.

Claus.