Non Dragon ROM 1-1

[WilkoUK]

Hi Folks,
Whilst I was inside the Dragon tweaking its video output I noticed that the second ROM chip isn't a Dragon 1-1 stamped ROM.
Any ideas what this new ROM is? An upgrade? How can I find out a list of commands available in the ROM (I used to know all of this stuff but 34 years is a long time ago)

[pser1]

Hello,
maybe you could try first just that
EXEC 48000 and see what happens
If the cursor turns blue instead of standard, it could be possibly a ROM chip programmed with the same alternate Basic.
You could verify memory with
PRINT MEM

cheers
pere

[robcfg]

If you could CSAVEM the rom area to a wav file and post it here, we could verify the rom contents.

The command would be CSAVEM"ROM",49152,65279,49152

[pser1]

Hello,

just wanted to tell you that the CSAVEM should be done after the EXEC or EXEC48000
In the contrary case you will send to the tape the DOS ROM assuming it was attached.
I am sure you knew it ... but

cheers
pere

[WilkoUK]

Hmm interesting.

When I EXEC 48000 it sort of boots and sort of doesn't..

Screen shot attached (apologies, I cut off the left hand side)

[pser1]

Well,
that means something ...
when executing 48000 the system switches to map1 (all RAM) and then copies the alternate ROM into RAM from $C000 on, after doing that it jumps to $C000 or to $C003 upon being a cold or warm start.
Looking at that garbage, for sure something is wrong.
Maybe the EPROM is wrong or simply it has not the alternate Basic.
Another possibility is that the RAM is not working alright (maybe faulty RAM). Is the machine a Dragon 64 or an upgraded Dragon 32?
By the picture it seems that you have a (possibly updated) Dragon32, the board is a Mark II and the RAM layout is clearly, to me, the D32 standard
You will tell us more on that machine ...

cheers
pere

[WilkoUK]

The machine doesn't hang or lock up, so I doubt its a RAM fault.

I wrote a debugging/dis-asm tool for the Dragon when I was about 14 years old. Wish I still had it now, I'd be able to read the assembly language code in the rom from 48000. Is there such a tool available now?

Unfortunately, I don't really know much history about the machine, I bought it about 5 or 6 years ago from eBay (I used to have one as a teenager, the Mk 1 that had the twin deck RAM).

If I can find or remember how I wrote the original basic program I'll dis-assemble the ROM and see what's inside it.

Quite Interesting!

[pser1]

You will find some Assembler programs in the archive ... Encoder09, Dream between them
If you look at this page:
http://archive.worldofdragon.org/index. ... d_Pictures
you will find all of the known used motherboards for Dragon 32 and Dragon 64
Try to find yours in that page and then we could talk about it.
If it were a Dragon 32 motherboard with the half-good RAM chips, and it had undergone the few changes needed to access the whole 64K
this would set a scenario, but I think that first thing is discover what hardware you have really inside your computer

cheers
pere

[tormod]

Hi, these 24-pin PROMs are 8KB, and this looks like a normal Dragon 32. The 1-0 PROM covers 8000-9FFF and the 1-1 PROM covers A000-BFFF. So there is no reason to exec 48000 on this machine. EXEC by itself should return FC ERROR by default on a normal Dragon 32 BASIC. At 48000 there is nothing (empty cartridge slot) so the garbage you get is normal.

Just save the "1-1" PROM with

Code: Select all

CSAVEM"ROM1-1",&HA000,&HBFFF,&H8B8D

and we can compare it to the standard ROM.

Of course, I would recommend swapping that 1-1 PROM with a DWLOAD EPROM

[Alastair]

As you can see below, the ROMs in my Dragon 32 do not have Dragon stamped on them but have the same markings as the highlighted chip, so the highlighted chip is likely to be normal.

D32_ROMs.jpg (40.56 KiB) Viewed 3822 times

Why some chips are stamped Dragon and others are not I cannot say, but I guess that when assembling the computers Dragon Data used whatever ROM chips were to hand.