Sinclair ZX80 / ZX81 / Z88 Forums

1024MAK wrote: ↑Thu Oct 05, 2017 6:44 pm

Moggy wrote: ↑Thu Oct 05, 2017 4:40 pm

1024MAK wrote: ↑Thu Oct 05, 2017 4:14 pm It could be that is simply a single ROM chip that is used, replacing the 8k byte BASIC ROM. If so, the start address will likely be 0x0000 so that the CPU executes it at power on.

Mark

I ask in all ignorance and wanting to learn, how does either the 4k 2732 or 2k 2716 inside the unit replace the 8k zeddy ROM?
Does it boot up from either one of them then hand back to the zeddy ROM to handle its housekeeping duties etc?
If so how does the zeddy ROM hand back control to the module?

Sorry, in a rush to finish my post as the train approached the station I was getting off at, I appear to have made a bit of a mess of it

Thankfully Siggi has cleared a way through the fog...

Mark

No worries Mark it happens, I find the idea of the module booting up with a bit of its own ROM then using the rest of the zeddies own ROM a brilliant idea.

Unfortunately I don't have the manual for Word Sinc II.3.

These are the keys I've found thus far:

Shift-1 Main menu
Shift-2 Print mark start/stop
Shift-3 Insert text
Shift-9 Cut text start/stop
Function-Shift-1 '
Function-Shift-2 almost equal to symbol
Function-Shift-3 division
Function-Shift-4 !
Function-Shift-5 arrow left symbol
Function-Shift-6 arrow down symbol
Function-Shift-7 arrow up symbol
Function-Shift-8 arrow right symbol
Function-Shift-9 Print with big font enable/disable
Function-Shift-Q line right
Function-Shift-W line left
Function-Shift-E [
Function-Shift-R ]
Function-Shift-T %
Function-Shift-Y \
Function-Shift-A @
Function-Shift-S line top
Function-Shift-D line bottom
Function-Shift-F pi
Function-Shift-G &
Function-Shift-H #

Notice Word Sinc II.3 does not use regular 32 letter columns with uppercase letters. It uses 40 letter columns with upper AND lowercase letters. See here: http://www.zx81.de/andre/zx91/_frame_e.htm

Moggy wrote: ↑Thu Oct 05, 2017 4:58 pm Thanks for that Siggi that makes sense to me now.

As for the EPROM contents If they were socketed and not soldered I would happily remove them and get the code.

I'm thinking hardware hack here.

If you take two empty sockets and wire them together from top to top. Now sockets are hanging from both sides of the wire, with free legs.

Then one of the sockets is pushed down on top of the eeprom to make physical connection.

The other socket is placed in an eprom reader.

Maybe this way it can be read without desoldering it.

Maybe this adapter is easier to make with sockets for wirewrap since the legs are very long. Then you can avoid soldering the sockets, but just wirewrap wires between the two sockets.

The EPROMS will not be directly usable in an emulator, but I think it will work on real hardware with a ZXblast or ZXmore. Here you can make any memory as ROM or RAM, and load to it before starting the machine at address 0.

However the software will need tape to work, as it uses custom tape routines. I think this can be worked around again with ZXblast which can save any part of memory when you “freeze” the machine and enter ZXblast’s menu. This might not work as the custom keyboard routine might hinder the ZXblast to see the double-shift commands that activate the ZXblast.

(Edit: ZXpand changed to ZXblast)

From the context I see that you write about zxblast, not zxpand.

Paul wrote: ↑Thu Aug 08, 2019 9:53 pm From the context I see that you write about zxblast, not zxpand.

Thank you. My mistake. Of course I meant ZXblast.

mrtinb wrote: ↑Thu Aug 08, 2019 12:46 pm I'm thinking hardware hack here.

If you take two empty sockets and wire them together from top to top. Now sockets are hanging from both sides of the wire, with free legs.

Then one of the sockets is pushed down on top of the eeprom to make physical connection.

The other socket is placed in an eprom reader.

Maybe this way it can be read without desoldering it.

I've made some picture to illustrate the idea.

First picture where two sockets are wired together. Here I have only wired 4 wire for illustration, but all legs should be connected from socket to socket.

Second picture is the first socket pressed down on the chip to read, and the second socket is inserted into an EPROM reader (this is a green chip holder for illustration purpose).

Give me a bit of time Martin and I might be able to dump the EPROM in the same way that I did the assembler EPROM, I shall play with this for a while.