ZXPAND and Lambda 8300?

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Paul
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ZXPAND and Lambda 8300?

Post by Paul » Mon Sep 26, 2011 6:34 pm

Hi
has this been tried?
At least the RAM should work or not?
I looked at the BUS description which looks similar to ZX81, but there seem to be some missing connections where it states internaly not connected.
Sir Morris, could you please state which lines are needed? Or have a look at the BUS description and say which missing lines have to be connected internaly.

Has anybody tried any ZX81 Hardware on the PC8300?
I only know the other way, the Lamda color module which works fine on ZX81 (with missing commands beeing made by pokes).

I wonder who has any experiences with Lambda 8300 (or compatibles)
In theory, there is no difference between theory and practice. But, in practice, there is.

sirmorris
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Re: ZXPAND and Lambda 8300?

Post by sirmorris » Mon Sep 26, 2011 8:42 pm

You need /M1 and /RESET connected. I'm surprised the machine could get away without /m1 on the expansion connector...

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mrtinb
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Re: ZXPAND and Lambda 8300?

Post by mrtinb » Thu Mar 22, 2018 8:12 am

According to this documentation it seems neither/M1 nor /RESET is connected.

https://k1.spdns.de/Vintage/Sinclair/80 ... 0180°).gif
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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mrtinb
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Re: ZXPAND and Lambda 8300?

Post by mrtinb » Sun Apr 15, 2018 10:12 pm

I can report that the ZXpand works ok with the Lambda 8300.

Since the Lambda 8300 has a different I/O-port for detection NTSC/PAL, an unmodified ZX81 ROM will assume NTSC and therefor the screen is unreadable. You can work almost in blind and use CONFIG "X" at the end, to change back to Lambda's built in ROM. Here I have only tried with a ZX81-compatible ROM in the Lambda 8300. I have not tried with original Lambda 8300 ROM.

https://youtu.be/N7CpivOsk20

What I type in blind is:

CONFIG "M=H"
LOAD "HI-Z"
N/L
CONFIG "X"
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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mrtinb
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Re: ZXPAND and Lambda 8300?

Post by mrtinb » Wed Apr 25, 2018 10:05 pm

I want to hardcode the ZXpand ROM for PAL, as the Lambda 8300 has a different PAL/NTSC detection.

I changed

Code: Select all

02DF: ADD A,1F
to

Code: Select all

02DF: LD A,37
This makes MARGIN be $37 always which I can read in the disassembled ZX81 ROM is for UK (PAL).

The two statements have the same 7 T-states, so timing should be similar.

Unfortunately this is not enough to hardcode the ROM for PAL.

Any suggestions?

P.S. I know it is not PAL / NTSC as the ZX81 has no color, but you know what I mean.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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mrtinb
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Re: ZXPAND and Lambda 8300?

Post by mrtinb » Thu Apr 26, 2018 8:38 am

As you can see, the picture is difficult to read.

This is a picture of the ZXpand Commander.

Image
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

olofsen
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Re: ZXPAND and Lambda 8300?

Post by olofsen » Sat Apr 28, 2018 10:55 am

Perhaps it is the INT routine? The routine in the ZX81 compatible Lambda ROM is I think slightly different from the normal ZX81 INT routine which the ZXpand is using?

nollkolltroll
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Re: ZXPAND and Lambda 8300?

Post by nollkolltroll » Sat Apr 28, 2018 8:34 pm

I seem to remember something about the Lambda using 208 cycles per line, whereas the ZX81 uses 207. This is strictly a vague feeling, not something to rely on...
/Adam

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Re: ZXPAND and Lambda 8300?

Post by dr beep » Sat Apr 28, 2018 9:22 pm

nollkolltroll wrote:
Sat Apr 28, 2018 8:34 pm
I seem to remember something about the Lambda using 208 cycles per line, whereas the ZX81 uses 207. This is strictly a vague feeling, not something to rely on...
Seeing the screen it looks like that indeed.

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Re: ZXPAND and Lambda 8300?

Post by mrtinb » Sat Apr 28, 2018 11:02 pm

dr beep wrote:
Sat Apr 28, 2018 11:09 am
What picture do you get from loading 1 of my 1K hires games?

This could determine if it is lowres or hirescontrol (timer per line).
The jumping text is what I had too when writing lowres too soon (not enough NL) to the screen.
I've load Humpty 1K in this video with the ZXpand ROM:

https://youtu.be/L0ehypS91Fk

Remember that Lambda 8300 does NOT do Pseudo Hires, WRX or UDG. This is due to the different ULA where charset is inside the ULA.
Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

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