How do you use a multi-slot expander (motherboard)?

[moggep]

Threadlift of the Century!

I was forewarned by your post in Forum64.

[...] my major question is about the ROM that is installed. It has a handwritten sticker that says "Screen ROM". Anyone knows what it is, and how to activate it?

Please take a look at the first program, EASYDUMP, in this thread.

The EPROM should be located in BLK5, but may not always be visible, depending on how the DIP-switches (especially 1 and 4) are set. The program stores a memory dump (5 corresponds to the range $A000..$BFFF, where most cartridge ROMs are located) on floppy, or SD-card with a SD2IEC, etc.

If you can provide the ROM image I will take a look at the code.

Thanks Mike, i'll have a look at it tonight when the kids are asleep.

[moggep]

Thanks for a great program.

Attached are the dump-files. There are three files in the archive, with different switch settings.

blk5-00a000 Dipswitch 1 off and 4 off
blk5-01a000 Dipswitch 1 off and 4 on
blk5-11a000 Dipswitch 1 on and 4 on

Hope you can get something out of it.

[Gyro Gearloose]

I plugged 5 VICs to one RAM cartridge once.

It didn't work.

[eslapion]

@moggep
What you have there is a very interesting cartridge. Instead of using multiple 8k x 8 SRAM chips or perhaps a single 32k x 8 SRAM chip, it uses 4 DRAM chips of 16k x 4.

This means it has a built-in system for multiplexing the addresses and a refresh system.

I have a schematic for doing something like that here but I have never tested it and I suspect it may be incomplete.

[Mike]

Attached are the dump-files. There are three files in the archive, with different switch settings.

To my surprise, the files came out with a size of about 47K. Actually they were supposed to be 8K in size.

You made a typo in line 22 of the program: POKE194,S uses the letter "S", not the digit "5". This made the program dump the whole memory from $0500 to $BFFF (including EASYDUMP itself) and thus I could infer what went wrong.

blk5-00a000 Dipswitch 1 off and 4 off
blk5-01a000 Dipswitch 1 off and 4 on
blk5-11a000 Dipswitch 1 on and 4 on

Unfortunately none of these 3 combinations turned up with recognisable ROM code in what the files saved from $A000 to $BFFF. However, the combinations 01 and 11 seem to map RAM into BLK5.

The combination 10 is missing. Maybe this one maps in the ROM.

If possible, please use *.zip instead of *.rar to produce the archive.

[moggep]

To my surprise, the files came out with a size of about 47K. Actually they were supposed to be 8K in size.

You made a typo in line 22 of the program: POKE194,S uses the letter "S", not the digit "5". This made the program dump the whole memory from $0500 to $BFFF (including EASYDUMP itself) and thus I could infer what went wrong.

Of course i did, it's obvious when you say it.

blk5-00a000 Dipswitch 1 off and 4 off
blk5-01a000 Dipswitch 1 off and 4 on
blk5-11a000 Dipswitch 1 on and 4 on
Unfortunately none of these 3 combinations turned up with recognisable ROM code in what the files saved from $A000 to $BFFF. However, the combinations 01 and 11 seem to map RAM into BLK5.

The combination 10 is missing. Maybe this one maps in the ROM.

If possible, please use *.zip instead of *.rar to produce the archive.

I'll give it another try tonight, with 4 files this time. Thanks for your effort.

[Mike]

I'll give it another try tonight, with 4 files this time.

If you just supply the missing combination (1 ON and 4 OFF), that is entirely sufficient.

As I wrote, the first three files already contained a dump of the address range in question (BLK5), even if some more of the memory was saved alongside it.

[moggep]

I'll give it another try tonight, with 4 files this time.

If you just supply the missing combination (1 ON and 4 OFF), that is entirely sufficient.

As I wrote, the first three files already contained a dump of the address range in question (BLK5), even if some more of the memory was saved alongside it.

Here's the missing piece. You were totally right, i made a typo in line 22.

[Mike]

Here's the missing piece. [...]

And Bingo!

A quick peek reveals a toolkit that is mapped into BLK5. The EPROM is only 4K in size, and so the original appears at $A000..$AFFF and is then mirrored to $B000..$BFFF.

SYS 40960 outputs some status/debug info of current BASIC RAM limits, position of screen RAM, and VIC register settings.

I will have to investigate further: this ROM possibly provides a BASIC editor capable of handling another number of columns and rows than the standard 22x23 layout.

[moggep]

Here's the missing piece. [...]

And Bingo!

A quick peek reveals a toolkit that is mapped into BLK5. The EPROM is only 4K in size, and so the original appears at $A000..$AFFF and is then mirrored to $B000..$BFFF.

SYS 40960 outputs some status/debug info of current BASIC RAM limits, position of screen RAM, and VIC register settings.

I will have to investigate further: this ROM possibly provides a BASIC editor capable of handling another number of columns and rows than the standard 22x23 layout.

Nice! And it would be even nicer if it is such BASIC editor.

I noticed a difference in the output if i try sys40960 two times in a row. After the 1st run it seems to occupy some of the RAM. (see pics)