ZXPAND and Lambda 8300?

[Paul]

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)

[sirmorris]

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

[mrtinb]

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

https://k1.spdns.de/Vintage/Sinclair/80 ... 0180°).gif

[mrtinb]

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"

[mrtinb]

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.

[mrtinb]

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

This is a picture of the ZXpand Commander.

[olofsen]

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]

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...

[dr beep]

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.

[mrtinb]

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.