SP-2-ZX81, the new ZX81-emulator for the 48K ZX Spectrum

[loftcat]

This is the official release of my NEW ZX81 EMULATOR for the 48K ZX Spectrum.
Fully software and much faster than my emulator from 1997.
The old emulator is also included.
https://www.mediafire.com/file/oiejfzmj ... X.zip/file

Late to this... but just wanted to say thanks, just what I've been looking for dr beep!

[dr beep]

This is the official release of my NEW ZX81 EMULATOR for the 48K ZX Spectrum.
Fully software and much faster than my emulator from 1997.
The old emulator is also included.
https://www.mediafire.com/file/oiejfzmj ... X.zip/file

Late to this... but just wanted to say thanks, just what I've been looking for dr beep!

Thanks,

better be sure to have the lastest version then.... v2.15

[loftcat]

Sure, but where can I find the latest version? The last version I can find on this thread is v2.13.

[dr beep]

Here is the TAP-file

Latest version has POP IX added to make games like MAYHEM run too.
Also a remaning address after LOAD taken from the stack.

Cbanges from 2.13

; v2.15
; SP-repair after LOADING (1 RET remained on stack)
; POP IX added as option to load start of intrupt
; MAYHEM from Revival Studios now working

; v2.14
; Bugfix JP PO,NN

sp2zx81v215.zip

(13.92 KiB) Downloaded 223 times

[dr beep]

Late to this... but just wanted to say thanks, just what I've been looking for dr beep!

Were you looking a long time?
Were you familiar with the first emulator?

Like to hear the story behind your search.

[loftcat]

Well I've not been looking for that long actually, in the back of my mind I knew there was at least one ZX81 emulator available for the Spectrum but hadn't investigated it. Recently I've been painfully trying to get my original cassettes to load (I say painfully because I have various modern easier methods of loading games and things, but I like the old tapes!). I suddenly remembered emulators and thought "what if I can turn a +2 into an ZX81 and try to load ZX81 tapes that way?". I have a +2 on the way with reconditioned datacorder, so my idea was whether I could make something work.

I've not had a chance to read through everything that you've provided yet dr beep, but it looks like ZX81 files need converting to Spectrum files for handling the different baud rate. If that's the case I'm noy sure about loading real ZX81 cassettes but I'm going to read through everything.

This looks like a nice emulator, when I've tried it out I'm keen see what it's capable of!

[dr beep]

Well I've not been looking for that long actually, in the back of my mind I knew there was at least one ZX81 emulator available for the Spectrum but hadn't investigated it. Recently I've been painfully trying to get my original cassettes to load (I say painfully because I have various modern easier methods of loading games and things, but I like the old tapes!). I suddenly remembered emulators and thought "what if I can turn a +2 into an ZX81 and try to load ZX81 tapes that way?". I have a +2 on the way with reconditioned datacorder, so my idea was whether I could make something work.

I've not had a chance to read through everything that you've provided yet dr beep, but it looks like ZX81 files need converting to Spectrum files for handling the different baud rate. If that's the case I'm noy sure about loading real ZX81 cassettes but I'm going to read through everything.

This looks like a nice emulator, when I've tried it out I'm keen see what it's capable of!

On a +2 you can add hardware and make the 128 run as a ZX81.

My emulator has a program to load ZX81 games and then saves them in ZX Spectrum speed.
I could have coded it to load at 300 baud, but then you keep loading at low speed.
Other advantage... I can use ZX Spectrum BASIC to add multiple devices to load from.

[dr beep]

I ran CLKFRQ.P on SP-2-ZX81

This program is a benchmark to test how good an emulator matches the real ZX81.

It counts the number of frames used for a fixed program.
When the emulator updates each screen the speed is 9.5%
However when the emulator updates each 2nd screen the speed is already 54.8%
1:4 updates set the speed to 76.1%
When 1:20 screen updates are done (max value) the speed goes to 94.5%

Now this is partly BASIC and the ROM is sped up to do that.
Not accounted for is the fact that the emulator is faster when a screen is shortened with JP (HL).
A game with unused screenlines can run faster when you do a TIMER DELAY FINDER.

The author also stated when he wrote this program that in many games with BASIC you could take out delays.
That is always possible.

[butchi]

Hi,
SP-2-ZX81 TAP fails to open on this 48K ZX Spectrum emulator:
link
. . . please confirm

[dr beep]

Hi,
SP-2-ZX81 TAP fails to open on this 48K ZX Spectrum emulator:
link
. . . please confirm

If it loads on other emulators it is not a SP-2-ZX81 problem.