EIGHTYONE PROBLEM

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siggi
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Re: EIGHTYONE PROBLEM

Post by siggi »

Hi Mike,
one more question: what is necessary to run the "spectrum rom" SP81.ROM on EO or on a real ZX81?
Using EO I took a 16K Zeddy, enabled WRX and loaded the SP81 rom. But the "Speddy" did not boot :-(

What is necessary on a real Zeddy? 16 K rom (batt-ram in my case) at the "rom side" of the resistors and >= 16 K ram (hires enabled)?

Siggi
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siggi
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Re: EIGHTYONE PROBLEM

Post by siggi »

Meanwhile I found a description and the source code of SP81 (see attached files). And the SP81 rom works on EO V0.42 :D (but not on newer versions :( ).

I put the SP81 rom into my Laptop-Zeddy (http://forum.tlienhard.com/phpBB3/viewt ... =305#p1642), where I have 2 banks of 16 KB EEPROM at address 0-16K (big enough to hold the SP81 rom). But it did not work :(

The reason is (IMHO), that my Zeddy is equipped with a M1-NOT circuit to run m/c above 32K (it has 64K ram).
But the SP81 rom has its DFILE below 16K (at the end of the unused rom space) and jumps to DFILE+32768 to generate the display (an address in range 32-48K). But there the ULA in my Zeddy does not catch the executed code to make the display (because of the M1-NOT circuit). So the display routines don't work :o

This rom would probably work on a Zeddy without a M1-NOT curcuit. But then m/c above 32K is not possible and Spectrum 48K m/c games won't run above 32K. So the SP81 rom can only be used to emulate a 16K Speccy.

To work on "modern" 64K Zeddies with M1-NOT circuit, the SP81-rom should have the DFILE above 16K (then 48K Spectrum programs with m/c up from 16 up to 48K could be run). But is there any unused space in the Spectrum ram (about 40 byte) to hold a DFILE (e. g. unused printer or other buffers)?

Siggi

Addendum: here is Mike's old description: http://web.archive.org/web/200707310757 ... .com/SP81/
Attachments
sp81.txt
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sp81.asm
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brancorp2000
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Re: EIGHTYONE PROBLEM

Post by brancorp2000 »

People I installed EightyOne v 1.12 and 1.18.
In both versions, when I try open TAPE MANAGER (CTRL+F9) it does not open the window.
whyyyyy????
Fruitcake
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Joined: Wed Sep 01, 2010 10:53 pm

Re: EIGHTYONE PROBLEM

Post by Fruitcake »

brancorp2000 wrote: Sun Oct 18, 2020 4:05 pm when I try open TAPE MANAGER (CTRL+F9) it does not open the window.
Have you tried selecting Gather Windows from the View menu in v1.18?
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