Different ROMs for Lambda 8300

User avatar
mrtinb
Posts: 1906
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Different ROMs for Lambda 8300

Post by mrtinb »

There seems to be quite a few ROMs that works with the Lambda 8300:
  • Lambda 8300
  • Marathon 32 (includes color keywords)
  • ZX81 ROM
  • Modified ZX81 for Lambda 8300
Can we get an overview on what features are in which ROMs?

What does the "ZX81 modified ROM for Lambda" give me, that the "ZX81 ROM" does not?
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
User avatar
mrtinb
Posts: 1906
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Lambda 8300 with ZX81 ROM (I think)

Post by mrtinb »

Lambda 8300 with ZX81 ROM (I think).

I inserted a ZX81 ROM, but that does not work. Maybe the Lambda insists on a modified ZX81 ROM.

https://youtu.be/Eyz3EM5ADJY
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
User avatar
gammaray
Posts: 590
Joined: Sun Apr 17, 2016 2:44 am
Location: Texas

Re: Different ROMs for Lambda 8300

Post by gammaray »

Your Lambda is probably PAL?... and your ZX81 does PAL or NTSC based on... what is it PIN22 of the ULA? Using R30 pullup resistor?

Lambda probably doesn't have that type of ULA...hmmm. ROM code changes on that maybe?

https://k1.spdns.de/Vintage/Sinclair/80 ... Kong/ROMs/

What about comparing schematic of US Futura 8300 and Lambda 8300?

https://en.wikipedia.org/wiki/Lambda_8300
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
User avatar
mrtinb
Posts: 1906
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Re: Different ROMs for Lambda 8300

Post by mrtinb »

Ah...

Lambda has different port for detecting PAL. That’s why I need a modified ZX81 ROM.


PC8300 I/O PORTS

I/O:NNFEh.R ;read keyboard (A8..A15=row) (and CAS.IN) (and JOYSTICK)
;(but no PAL/NTSC bit here, unlike ZX81)
I/O:FF7Eh.R ;read PAL/NTSC flag (A7=row) (via diode from A7 to KEYB.0)
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
User avatar
1024MAK
Posts: 5101
Joined: Mon Sep 26, 2011 10:56 am
Location: Looking forward to summer in Somerset, UK...

Re: Different ROMs for Lambda 8300

Post by 1024MAK »

The other difference I believe, is the character dot matrix data is in ROM on the ZX81, but in the "ULA" on the Lambda...

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Different ROMs for Lambda 8300

Post by Andy Rea »

1024MAK wrote: Tue Apr 03, 2018 11:46 pm The other difference I believe, is the character dot matrix data is in ROM on the ZX81, but in the "ULA" on the Lambda...

Mark
With this lambda talk lately i was looking at the schematics wondering how on earth the display was generated... That explains it... Cheers
what's that Smell.... smells like fresh flux and solder fumes...
User avatar
mrtinb
Posts: 1906
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Re: Different ROMs for Lambda 8300

Post by mrtinb »

So the half shade chars are replaced with diagonal triangles and a gaming “racing cars” char.

The £ char is replaced by a gaming “spider”.

The weird thing is that “:” and “?” chars are replaced with gaming chars as well. Here we have gaming “summer bird” and gaming “ghost”.
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
User avatar
mrtinb
Posts: 1906
Joined: Fri Nov 06, 2015 5:44 pm
Location: Denmark
Contact:

Re: Different ROMs for Lambda 8300

Post by mrtinb »

mrtinb wrote: Tue Apr 03, 2018 11:27 pm Lambda has different port for detecting PAL. That’s why I need a modified ZX81 ROM.
Unfortunately http://problemkaputt.de/zxdocs.htm#lambda830 states that the modified ZX81 ROM for Lambda is hard coded to 60 Hz. That will not work with my European tv. :cry:
Martin
https://zx.rtin.be
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube
User avatar
XavSnap
Posts: 1940
Joined: Sat May 10, 2008 4:23 pm
Location: 'Zx81 France' Fb group.

Re: Different ROMs for Lambda 8300

Post by XavSnap »

Lambda8300.jpg
Lambda8300.jpg (39.19 KiB) Viewed 16880 times
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
User avatar
gammaray
Posts: 590
Joined: Sun Apr 17, 2016 2:44 am
Location: Texas

Re: Different ROMs for Lambda 8300

Post by gammaray »

Sounds like someone with decent assembler skills would need to go after this one.

Addendum: The Futura 8300 was the unit for the U.S. so maybe it is built into the original ROM code/ULA to switch video?
5-TS1000,UK ZX81<-Sheelagh, US ZX81, 2-TS1500/KDLX , 3-TS2040 printer, 2-TS2020 cassette decks, ZXPAND+AY, ZeddyNET, ZXBlast, UDG, ZX8CCB, AERCO, BUILDS/REPAIRS ZX Spectrum, ZX80 Minstrel, ZXMAX48 v1 v2, 2-TS-2068, ROM, 16kRAM
Post Reply