Hehe, I doubt someone caries the same 150ns (or whatever was hot back in 1988)

But due to sheer amount of hardware that needs maintenace, I am sure someone does produce pin-compatible modern ICs with fater access time (like 60ns or so...)

This is why I am asking for true and tried IC models with a known online vendor. I might end up getting in touch with usuario, if I can not get ICs cheaper anywhere else

Normally if you search for an IC number of a discontinued product you'll be automatically referred to its newer counterpart. If you look at whatever datasheet is has it'll also say that it replaces XX IC. That or just ask any good electronic-parts vendor.

Just look on the existing two IC's to see which type they are. If you post them here maybe someone knows a suitable replacement.

Yeah, I'm doing my research now... Once I gathered enough information, I'll create a new dedicated post with all the clues, links to pictures (I already disassembled WSX) and theories

Here is an e-mail, but I think it's in Portugese and av.com doesn't give meaningful translation... If someone could please summarize what folks from MSXBR list are talking about, I'll be very grateful!


[MSXBR-L] RE:Chips de memoria-complemento
Kim Daniel bitcomputer@hotmail.com
Wed, 11 Sep 2002 00:45:44 -0300

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--------------------------------------------------------------------------------

>From: badmsxboy@ig.com.br
>To: msxbr-l@listas.unesp.br
>Subject: [MSXBR-L] RE:Chips de memoria-complemento
>Date: Wed, 11 Sep 2002 00:28:05 -0300

Oi,

>Vou dar uma pesquisada na Rua Aurora amanha, ver se consigo encontrar la
os
>chips!
>Vou tentar esse mesmo q vc indicou os ICM44256-60 . Qual a marca desse CI
vc
>sabe Norikuni? ai facilitava um pouko mais, mas acho q ja consigo.
>Vou aumentar pra 256k, ai ja da pra rodar Sd-snacther, Dos2, Game master2
>com execrom(ja q nem a rom da funet do gmaster1 funcionou, so da Wrong
File
>Type com /g1), snatcher em portugues, Game Colletion do nemesis , e outras
>coisas mais. Eu acho q seria interessante talves no futuro instalar os
512k
>mais por poucas coisas, mas igualmente boas como metal gear2 eng/port e o
>shalom portugues c/512k tb. Se eu tivesse megaram c/ 512k ou 768k talves
nem
>eskentasse a cabeca mais. Quem sabe se o Carchano tiver como vender-me uma
>dessas!

Legal. Boa aventura e boa sorte.. Tome cuidado com ferro de solda.
Saiba que o Execrom funciona apenas com megaram. Game Master 2 com memory
mapper.
Existe uma versao em disco para Metal Gear 2 com Memory Mapper, tanto para
256kb ou 512kb. R-Type tambem e Hydlide 3. Nao precisa tanto de
512kbytes...
So' vale a pena com comando chamado call ramdisk.. assim voce copia disco
para RAM e vice-versa..

>O WX e um micro MSX 2+ completissimo, tem kanji rom, fm-sound, disk-drive
3
>1/2, saida p/ cassete tb q usa em alguns jogos, e etc, de forma q agora c/
>256k so uso os slots para uma megaram e um scc e esta completinho tudo!
>Pretendo adaptar um encaixe para facilitar o uso do datacorder tanto com o
>WX e com o DDplus 1.1.Tb queria saber, ja peguei a pinagem da saida de
>cassete do WX, e tenho a pinagem do cabo de datacorder da gradiente.
>Pretendo ligar assim pra usar nos dois:
>Datacorder>cabo macho datacorder do expert>encaixe femea cpu
>expert>adaptacao de pinagem das 2 cpus>encaixe macho 8 pinos WX>encaixe
>femea traseira do WX.

Com WX ou WSX, tem um comando do BASIC especial para habilitar 7mhz. Por
isso, vale a pena com isso. Parabens pelo seu FSA1WX.

>Assim eu posso rapidamente retirar de 1 para o outro micro facil.
>Tenho uma cpu queimada do expert cinza, vou retirar o saida femea desse,
pra
>plugar o cabo do datacorder nele. Preciso achar algum encaixe desse de 8
>pinos, sera q por la na aurora tb teria ? Ou alguem sabe qual aparelho
teria
>esse encaixe para eu poder canibalizar de algum aparelho estragado?
>Obrigado mais uma vez

Vixe.. uma loja que vende o plugue de 8 pinos na esquina de rua vitoria com
parede laranja e ter manual sobre esse cabo para saber como soldar..
No manual que veio juntos com Expert tem sobre isso..
Boa sorte..
xau...

Quote:

I expand Panasonic WX/WSX to 256kB for 40 euros and 512kB for 55. send me a e-mail: usuario_msx2@yahoo.es best regards

Yo-yo man, I've sent you an e-mail. Please read it. Basicly I want you to sell me the chips and consult me by e-mail on installation. Shipping WSX to and back from Spain will kill me

Here are some pictures of Panasonic WSX motherboard:

Full motherboard picture: tht.net/~aoboroc/msx/a1wsx01.jpg
Please refer to this picture to see where particular shot was taken from.

Lower left corner:
tht.net/~aoboroc/msx/a1wsx02.jpg
Four chips on the left from Z80B with marking:
LH2464-12
SHARP Japan
8934 7 S
I think it's 4 x 32KByte = 128KBytes of VRAM


Next:
tht.net/~aoboroc/msx/a1wsx03.jpg
On the left from Z0H is an empty socket to solder 28 or 32 pin chip. The markings are:
IC15 - 1M/512K
I guess this is a place for extra ROMs, for stuff like CP/M or Yamaha Painter or may be MSXDOS 2.20 ROM

Next to the empty socket:
tht.net/~aoboroc/msx/a1wsx04.jpg
tht.net/~aoboroc/msx/a1wsx05.jpg
3 x 32 pin chips (IC16, IC17 and IC18) and 2 x 28 pin chips, I guess this is all the ROM firmware.

The markings are:

(IC16 - 32 pin)
Japan (c) MEI 1989
MB834000A-20
4D3 AA 8941 T00

(IC17 - 32 pin)
Japan (c) MEI 1989
MB834000A-20
4B0 AA 8935 R10

(IC18 - 32 pin)
Japan (c) MEI 1989
MB834000A-20
4D4 AA 8945 T00

(IC19 and IC20 - 28 pin)
Japan
8464A-15L
8852 T56 L

Above the gap between IC18 and IC19 where is a place for unmarked 16 pin chip. I am afraid it could be the place for the mapper chip... I need help finding out if I do have a mapper. I remember seing a nice PEEK/POKE basic test to check if mapper is present...

HERE IS PROBABLY THE MOST IMPORTANT PART
tht.net/~aoboroc/msx/a1wsx06.jpg
Motherboard has four sockets for (I guess) 20-pin DRAM chips: IC21, IC22, IC23 and IC24

IC21 and IC24 are empty and the marking on the board says "1M", which I guess means 1MBit, i.e. 256KByte, so two chips should
give us 512KBytes of RAM! Brazilian e-mail above hints that I should try to buy ICM44256-60 chips and corresponding capacitors... Is that correct?

IC22 and IC23 have same type of chips as in VRAM corner:
LH2464-12
SHARP Japan
8934 7 S
I think it's 2 x 32KByte = 64KBytes of RAM
If my guess about IC21 and IC23 is right, then can I also desolder IC22 and IC23 and solder two more ICM44256-60 chips to get 1MByte of RAM? Because that would be fantastic

On the right from RAM chips there are three more empty sockets for 14-pin chips, marked IC27, IC25 and IC26:
tht.net/~aoboroc/msx/a1wsx07.jpg
I don't have a clue what they might be used for...


Another thing: this motherboard is so solid and is constructed to simple, that it looks like an ideal candidate for move to PC AT case It will be 100 times easier to fit it, and not the boards from Philips NMS 8250...

Thank you all for your help!

OKI 20-pin plastic DIP chip MSM514256CL (the slow low power consumption version)
262144-words x 4-bit == 256KBytes?

Will this chip work in Panasonic A1 WSX?

Document from OKI: www.oki.com/semi/datadocs/doc-eng/msm514256c.pdf

Yeah, it looks like the chips I am looking for are commonly reffered as 44256, and as such are awailable from many sources. Most cheap way is to scavenge them from an old 286 or early 386 computer...

44256, 44258
44256, 44258
256kx4 DRAM.

     +---+  +---+
  D0 |1  +--+ 20| GND
  D1 |2       19| D3
 /WE |3       18| D2
/RAS |4       17| /CAS
     |5 44256 16| /OE
  A0 |6 44258 15| A8
  A1 |7       14| A7
  A2 |8       13| A6
  A3 |9       12| A5
 VCC |10      11| A4
     +----------+

Yeah, I found mistake in my previous assumptions:

One 44256 chip holds 256 Kilowords, each of 4 bits. It's actually 128KBytes, not 256... So even if I unsolder two existing 2464 chips and add 4 x 44256, this will give me 512KBytes and not 1MByte

Still 512KBytes is a lot for MSX2+. I can only see the need for more then 512KB for Uzix...

Uhm... I think it is also possible to use a 4256 chips like TMS4256-15N (150ns)

They are in DIP-16 form-factor, so they won't fit in existing places, but I think it is possible to use short wires to solder them in...

Too bad I'm so incompetent in electronics

Quote:

I need help finding out if I do have a mapper. I remember seing a nice PEEK/POKE basic test to check if mapper is present...

10 PRINT"HELLO WORLD"
OUT (&HFE),4
LIST

if this does not list the '10 PRINT"HELLO WORLD"' then you do have a mapper.

OUT (&HFE),3
LIST

now your program should be back.

Some weeks ago I upgraded my A1-WX to 512K. Doing the same for WSX is pretty similar
I used these old PC chips: HYB514256A-70, but any 44256 memory 4 bit*256K (DIP type) should work. Just check they are not too slow.

I'll try to explain later how to do it.

BTW: WSX has mapper

Quote:

OUT (&HFE),3 LIST now your program should be back.

Shouldn't it be OUT &HFE,1?

Some notes about the memory expansion:

- Remove IC22 and IC23 chips and capacitors (you can use that chips to upgrade your VRAM to 192K)
- Put that capacitors and 44256 chips in IC21 and IC24
- Solder over those chips another 44256 chips (so you have 4 in total), but leave pins 17 unsoldered. Raise that pins to avoid contacts, and fix both with a wire.

(In the other side of the mainboard)
- Search for the MSX engine T9769.
- Next to it you can find printed on board (J3) and (J2)
- Remove the resistor in (J2)
- Solder a sort wire in (J3), so you get +5V in pin 52(T9769)
- Unsolder T9769 pin51, raise it a bit, an connect it to +5V (i.e.: to pin 52)
- Fix T9769 pin50 with 44256 pin17.

I think it is not so difficult, but be very careful when desoldering pin51 of T9769.

DISCLAIMER: made it at your own risk