Lambda 8300 ROM disassembly

Post Reply
User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Lambda 8300 ROM disassembly

Post by stefano » Thu Jul 23, 2015 2:48 pm

I'm proud to annonunce I was able to compare the commented ZX81 ROM assembly listing and the Lambda ROM disassembly and to comment a good portion of it.

It is an amazing piece of code, a considerable effort was made to obfuscate the binary fingerprint of the derived ROM, but also several improvements were inserted.

I was impressed by the many smart tricks applied to save code space, I thing that it can be an interesting peek for all the surviving assembly programmers in this list !!

EDIT: 2015/07/31 - updated (BASIC tokens and keyboard codes decoded + improvements and fixes).

EDIT: 2015/08/03 - furtherly updated (sound code, interpreter engine and display driver).

EDIT: 2015/08/11 - more fixes and updates
Attachments
lambda.zip
Lambda 8300 ROM disassembly (Latest update, 2015/08/11)
(59.87 KiB) Downloaded 127 times
Last edited by stefano on Tue Aug 11, 2015 11:16 am, edited 4 times in total.

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Thu Jul 23, 2015 3:13 pm

Last minute correction: please be aware that the comments aside the FP-CALCULATOR opcode tables need a little fix: the opcodes related to the "true binary operations" must be updated with a progressive HEX code.

EDIT: corrections are now applied to the updated file.

sascha2000
Posts: 57
Joined: Fri Jul 22, 2011 2:13 pm

Re: Lambda 8300 ROM disassembly

Post by sascha2000 » Tue Aug 04, 2015 9:12 am

Hello,

very good work. Thank you for the same.

I think the Lambda is such a nice clone, it is worth to work with it.

I have installed the ZX81 compatible ROM on it, except hires graphics, it runs text mode apps very well.

https://www.youtube.com/watch?v=lH8igenBmuY

Regards
Sascha

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Tue Aug 04, 2015 9:31 am

Thankyou,
I used it as a cross-reference to prepare the z88dk support, now at an half-working stage.
A lot of the experience coming from the ZX81 work can be reused !
I have prepared a compiled prototype (in attachment) and I'd like to know if it works.
The game barely runs because of the lack of a complete text driver (the display does not scroll and some character should be mapped differently), but it can be played.

I need to know whether the picture is stable on the real hardware (PAL and NTSC) and if the WAV format is valid for the LAMBDA. Can anybody help ?
Attachments
lambda-adva-prototype.zip
(235.56 KiB) Downloaded 86 times

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Fri Aug 07, 2015 10:17 pm

The new Lambda 8300 target port is almost ready in the z88dk CVS tree. Hopefully the first nightly compiled release will be available tomorrow morning ;)

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Sat Aug 08, 2015 10:08 pm

Ok.. actually something went wrong, let's hope for tomorrow :S

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Tue Aug 11, 2015 11:23 am

First nightly releases are coming out.
Whatch out ! A couple of bugs are still creeping in but most of the zx81 functionalities are already present and working: (SLOW mode support, blocky graphics, CHROMA81-style APIs, interfacing to BASIC program and variables, ultra compact ROM based Floating Point library but a faster z88dk provided option available..)

sascha2000
Posts: 57
Joined: Fri Jul 22, 2011 2:13 pm

Re: Lambda 8300 ROM disassembly

Post by sascha2000 » Tue Aug 11, 2015 4:29 pm

Hello Stefano,

sorry I was ill and so I did not read your thread.

>I have prepared a compiled prototype (in attachment) and I'd like to know if it works.

I will try to run it on my lambda. This may take some days .... please be patient ...

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Tue Aug 11, 2015 4:58 pm

Please don't apologise !!
I appreciate any kind of feedback, the past experiences taught me not to fully trust the emulators :mrgreen:

User avatar
stefano
Posts: 378
Joined: Tue Dec 11, 2012 9:24 am
Contact:

Re: Lambda 8300 ROM disassembly

Post by stefano » Tue Aug 11, 2015 5:00 pm

Forgot to say that there is a couple of entries in the "games" section you might prefer :P

Post Reply