Hello.

Messing around with the Mainboard, the resistor, connected to one of the ram-ic's broke of the mainboard. Anyone have a Photo shoot close up at this area ?

I dont know where to solder the resistor again

Henrik Gilvad who modified this Turbo-R used normal resistors not smd.

-Claus-

no photo but this description on Hans Otten MSX Info pages

512 kB RAM in the Panasonic FS-A1ST MSX turboR


Required

· 2x 44C256 RAM IC's

· 2 SMD-capacitor 100 nF

· 2 SMD-weerstand 100 Ohm

· 1 resistor 10 kOhm

Follow the next steps:
1. Solder the RAM IC's in the empty sockets IC31 and IC33.
2. Solder the SMD capacitors 100 nF on the empty locations C138 and C140.
3. Solder the SMD resistor 100 on the empty location R55.
4. Solder a 10 kOhm resistor on the empty location R41.
5. Solder a SMD resistor 100 Ohm on the empty location R229 on the bottom of the PCB!
6. Start the turboR ST and it should show 512KB!

I knew this, but i think Henrik Gilvad used another way.
Because one of the ram-ics are connected with a wire to a resistor, wich maybe are connected to the PCB.
But i am not sure.

-cb-

Quote:

6. Start the turboR ST and it should show 512KB!

Also, it should run about 2.5% slower.

Huh, why?

Quote:

Huh, why?

Refresh

Crazy Boss : take a photo of your Turbo-r modification and i can hepl you

i have a ST with 512k memory and speed is same ??

i have a GT with 1Mo memory with Simm 30 and speed is same

Is there still someone around who performs such things? I have an ST w/ 256kB RAM, I'd like to have 512kB or 1MB (SIMM solution). But there's the thing, I can't solder SMD...

i can upgrade your ST to 512 or 1024 but i am french

sold SMD "CMS" in french is possible with a little iron solder

i desold resistor to broken drive 1.44 PCB to sold in MSX board

Jipe. I heard its very risky to make the 1024 upgrade in a turbo-r ?

Can you update the A1ST to 1024 too ? or only the GT?

How about 4mb in turbo-r ?

Now first i have to get my mainboard working

By the way about the 2.5% slower i think the meaning is - its slower to boot cause for the extra memory check

The computer should not be slower when performing

-Claus-

for expand to 1Mo added a little board with a LS670 , LS367 , LS00 and LS32 for memory mapper (i can scan the schema)

on GT sold J302 , desold R352 and resold it on R353

on the ST is more dificult because cutting wire under pin 18 of the rR800 is not easy
second difficult sold a wire on pin 18 R800 and don't strap other pin
sold a strap on R229
desold R206
strap R206 near D22 to A14 ( i have the schema)

i can send a mail with schema for ST and GT but info are in french

http://www.passionmsx.org/modules/xcgal/displayimage.php?pid=1232&album=97&pos=8

you can see a 1Mo extend in a ST with Chip directly on support

no Simm no Board and no problem with the keyboard film

in the Simm extend the components destroy the keyboard film

look the CMS resistor near the ram with special position for bank 0 of memory

Quote:

By the way about the 2.5% slower i think the meaning is - its slower to boot cause for the extra memory check

No, the whole system actually slows down since the tR uses DRAM and not SRAM. This means each bit needs to be refreshed periodically; more bits means more refreshing (and less processing).

Note that adding the 1MB SIMM extension doesn't increase this refresh delay. I think because it doesn't use the tR refresh mechanism. Makes me wonder if a GT with a 1MB would actually become faster with 1MB. Or maybe it will if you desolder the extra 256K from the mainboard.

Ok i took a photo of the ram-ic's.

The picture is a bit fussy

Photo here ===> http://mtxworld.dk/ram-a1st.PNG

-CB-