Sharp PC-G850VS Reflashing?

[toml_12953]

The ROM of the VS model (not the V model) is in Flash memory which means it can be changed through software. Does anyone know how? My goal is to translate the STAT and BASE-N menus to English. This should be doable as long as the computer doesn't do a checksum calculation on the ROM. I just need to know how to get the code out of ROM and rewrite it after I change it. If I can do it, I'll make the ROM image available to anyone who wants it.

[Zaphod]

(09-21-2018 05:54 PM)toml_12953 Wrote:  The ROM of the VS model (not the V model) is in Flash memory which means it can be changed through software. Does anyone know how? My goal is to translate the STAT and BASE-N menus to English. This should be doable as long as the computer doesn't do a checksum calculation on the ROM. I just need to know how to get the code out of ROM and rewrite it after I change it. If I can do it, I'll make the ROM image available to anyone who wants it.

I was literally thinking about this last night, I was gonna rip my spare 850 open and see what’s knocking about inside.
(I.e. what hardware is actually in there)
There might even be an opportunity to up the memory , I’ve not studied the memory map too closely yet though as to what’s already been apportioned to what.

One may be able to read the ROM with the built in MON at least.

And indeed, as long as it doesn’t checksum itself then it should be easy peasy.

[Zaphod]

The Flash ROM is an EN29F040A-70TCP (512Kbit x8)

There are two COB devices close to the LCD (One is much larger than the other, but both linked to display area.)
Another COB virtually next to the Flash ROM (potentially the user-program RAM ?)
The Flash ROM and the S1L50752 (35.7k ASIC Gate array) are the only non-COB devices

Datasheet for the Flash:
http://pdf.datasheetcatalog.com/datashee...9938_1.pdf

Datasheet for the ASIC:
https://global.epson.com/products_and_dr...000473.pdf

That's all for now, I've got various pics of the board too

By the way, discovered the built-in MONitor is blocked from accessing certain areas of the map (for obvious reasons)

So we'll have to go in via the 40way system bus connector
I'm hoping this is universal for the sharp's ?
I thought I'd seen the pin out in the English manual, but I can't find it right now
I found a pin out for the PC-E220 which is probably the same
http://wwwhomes.uni-bielefeld.de/achim/p...on-bus.txt

[toml_12953]

(09-21-2018 06:00 PM)Zaphod Wrote:  

(09-21-2018 05:54 PM)toml_12953 Wrote:  The ROM of the VS model (not the V model) is in Flash memory which means it can be changed through software. Does anyone know how? My goal is to translate the STAT and BASE-N menus to English. This should be doable as long as the computer doesn't do a checksum calculation on the ROM. I just need to know how to get the code out of ROM and rewrite it after I change it. If I can do it, I'll make the ROM image available to anyone who wants it.

I was literally thinking about this last night, I was gonna rip my spare 850 open and see what’s knocking about inside.
(I.e. what hardware is actually in there)
There might even be an opportunity to up the memory , I’ve not studied the memory map too closely yet though as to what’s already been apportioned to what.

One may be able to read the ROM with the built in MON at least.

And indeed, as long as it doesn’t checksum itself then it should be easy peasy.

I had a thought (I occasionally do!) The author of the Sharp calculator emulator must have been able to get the ROM out somehow.

http://pockemul.free.fr/

Tom L

[Zaphod]

Quote:I had a thought (I occasionally do!) The author of the Sharp calculator emulator must have been able to get the ROM out somehow.

Interesting.

One could always pull it out (and back in again) from that system connector, or if needs be (would be a fair bit of work) direct from around the chip, solder in fly leads to the various via’s and then jury-rig those into a Batupo’s socket (which I’ve got)

[toml_12953]

(09-22-2018 08:48 AM)Zaphod Wrote:  

Quote:I had a thought (I occasionally do!) The author of the Sharp calculator emulator must have been able to get the ROM out somehow.

Interesting.

One could always pull it out (and back in again) from that system connector, or if needs be (would be a fair bit of work) direct from around the chip, solder in fly leads to the various via’s and then jury-rig those into a Batupo’s socket (which I’ve got)

No need (at least for version 1.02) Here it is:

https://www.dropbox.com/s/k4xhqraha4l9qb....zip?raw=1

[Zaphod]

Strange they're in 16k blocks , as the chip has eight 64k blocks

So 5.5 of the 8 blocks are used , plenty of space for other stuff

I'm tempted to buy a TSOP to DIL adaptor (£28) and remove the chip on my spare one....

[toml_12953]

(09-22-2018 10:51 AM)Zaphod Wrote:  Strange they're in 16k blocks , as the chip has eight 64k blocks

So 5.5 of the 8 blocks are used , plenty of space for other stuff

I'm tempted to buy a TSOP to DIL adaptor (£28) and remove the chip on my spare one....

I find it strange that Sharp moved ROM to Flash but didn't put in any way to flash the chip in place.

[Zaphod]

(09-22-2018 02:04 PM)toml_12953 Wrote:  I find it strange that Sharp moved ROM to Flash but didn't put in any way to flash the chip in place.

But there is !, all the address lines (and bank select's), and data lines are available on the 40p system connector.

OK, it will need some software and hardware to drive it..... but it's there.

Albeit they probably flashed the ROMs en-masse prior to fitting , but the ability to re-flash after build is still there.
I'm still struggling finding a 40way edge connector that will accept a thin 1mm-ish PCB, so if I gonna read/write I'll probably tack in flying leads around the ROM (whilst in place)

[Zaphod]

[foroplus]

I don't know if this gonna help, but you have a G850V emulator here. Maybe you can use an hexadecimal editor and test some changes on the PC before trying to do it on a real calculator.
http://basic.hopto.org/basic/emula.php

[Zaphod]

This is where you can attach a piezo buzzer:
(I saw it on some website the other day)

Looks like you can attach a backup battery just to the east of these two pads .....

[Zaphod]

(09-22-2018 05:28 PM)foroplus Wrote:  I don't know if this gonna help, but you have a G850V emulator here. Maybe you can use an hexadecimal editor and test some changes on the PC before trying to do it on a real calculator.
http://basic.hopto.org/basic/emula.php

Good idea