Tape to EPROM possible ?

[kolbeck]

One approach to auto run a P file from eprom EAS16K can be found here https://ws-nbg.de/zx81/main.php

[XavSnap]

No autorun on this wiring diagram...
A P file ... is a binary (ASM) ?
The BASIC can't run under a ROM @ $4000 and can't be launch without a ROM SYSTEM hack.
We had to jump to an ASM routine to the "RUN" command or the end of the "LOAD" routine, but in the $0000-$2000 memory segment.

In case of a single byte changed in this segment:
http://zx81.ordi5.free.fr/brico/RAMTOPoMATIC/

[kolbeck]

I haven’t build this, but my understanding is that it allows you to transfer a zx81 tape file to eprom, which is then launched at boot using a special boot loader, that transfer the program to ram and starts it. I would also assume that the boot Rom swaps itself out. The reference to this was more about the concept “tape to eprom”

[XavSnap]

We had to:

1- Patch the BASIC ROM to intercept the end of BASIC ROM loading, before the "K" display (?offset?).
2- Jump to a LDIR routine in the "P" ROM (somewhere in your BASIC program).
3- jump to the end of LOAD Routine (JP $046F)
4- The P file must be saved using a 9990 SAVE "prg" + 9999 RUN (autostart mode using RUN 9990)

[1024MAK]

Alternatively, a micro controller could produce the required keyboard key presses in sequence. That then means there is no need to modify the Sinclair BASIC ROM.

Is this tape file/program a BASIC program, a machine code program or a mix of both? And is it a commercial product or something written by you?

Only, if this is a program written by you, if using the method of modifying the Sinclair BASIC ROM, it’s a bit easier than if it’s a commercial product.

Mark

[kolbeck]

OK, got this up and working - so it's now possible to put a P tape file into an eprom, which is then AUTORUN when your ZX81 is powered on.

What is needed?
- My ZX81 external EPROM interface, that supports 16KiB ROM in the space 0-0x3fff on GitHub (or similiar device that allows custom ROM in 0-16k area)

The EPROM is organized as
- 0-0x1fff, ZX81 ROM with small modification
- 0x2000 - 0x3fff: boot code and P file to run

The ZX81 ROM modification is based on the concept of "ZX81 AUTOBASIC - Wilf Rigter - 1997", as part of this modification the ZX81 jumps to 0x2000 which copies the P file to memory in a LOAD fashion. Hold shift down on powering up to skip to normal operation.

With 16K rom image, there is space for 8K data to contain the boot code and P file - using the smart compression ZX0 it's possible to fit most 16K programs, making this interface a nice "cartridge" like of setup

[kolbeck]

Here is a video of my setup in action - all more or less DIY/homemade

https://youtube.com/shorts/YK3HYUyBtW4? ... R4pPWHy7F0

[mrtinb]

Cool work!

[XavSnap]

AUTOBASIC:
https://quix.us/timex/rigter/AutoBasic.html