Thoughts on Einstien "Stolen" Software?

Include new and ported/converted games, and old games/tools. Subjects about CP/M software goes in the CP/M Forum.
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Crazyboss
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Thoughts on Einstien "Stolen" Software?

Post by Crazyboss » 02 Oct 2018 14:34

Hi.

As most of us know by now some software companies called: "Merlin Software", "Syntax Software" and "Orion Software" - released Memotech Software, mostly under other names for the Tatung Einstein Computer.

I wonder if those people in some way got access to the Source codes. As you might know I have released some "new" Memotech games, converted from other Systems like. Sega SG-1000, MSX, Sord M5 and ColecoVision. Normally it take sometimes, cause you need to create a assembler Source from a binary file, if you have the source code its quite easy. And using 1980s tools I bet it took much longer time to create a usable source code than it takes today.

Since the games they converted back then, both was from Continental Software and MegaStar games, make me wonder, if they used the same persons or companies to make the final product ? - I mean did Continental Software and MegaStar Games send the source to some company which recorded it to tapecopies, and in that case could some one steal a copy of the source and supply those companies with the source ?

They still needed to emulate the Soundchip and the Joystick/keyboard reading, but I noticed mostly they will not emulate the noise channel and some times they dont change the name. As I know EinStein games run at org. 0x100 and most MTX tape games are 0x80FF.

I think Andy Key, told me ones, he was pretty sure he did not supply any one with the sourcecode.

Any Thoughts on this subject ?
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Tony Brewer
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Re: Thoughts on Einstien "Stolen" Software?

Post by Tony Brewer » 03 Oct 2018 15:37

A diskette was sold that allowed some extra Spectrum games to run on the Einstein Speculator which I knew nothing about at the time, despite it being my device.

The Einstein had an interesting hardware "feature" - the VDP /INT pin was not connected to anything! I met the chief designer during a visit to the Tatung factory in Telford. I forget his name now and he must have died quite some time ago.

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Re: Thoughts on Einstien "Stolen" Software?

Post by Crazyboss » 16 Oct 2018 17:05

Tony, maybe it was the same as the ColecoVision. The VDP was connected to NMI instead of INT.
Thats why its harder to port games to the ColecoVision, its much easier with the other systems since they all use INT.

Many of the Memotech titles never used Interrupts. AstroPAC did, but it was not ported to Einstein as I know.
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Tony Brewer
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Re: Thoughts on Einstien "Stolen" Software?

Post by Tony Brewer » 19 Oct 2018 16:17

The Einstein VDP /INT is not connected to Z80 /INT or /NMI or anything else. I couldn't believe it when I found out and therefore converting the Speculator was not as simple as it should have been.

Luckily CTC channels 2 and 3 can be cascaded (ZC2 tied to C/T3) and I programmed channel 2 in timer mode to pulse ZC2 every 9.85 ms (/INT disabled) and channel 3 in counter mode with time constant 2 (/INT enabled). The hardware connected /INT to /NMI and I could generate an /NMI after 19.7 ms.

Before refreshing the display in the NMI routine, I polled the VDP interrupt flag F after saving the registers and other necessary code, then re-programmed the CTC as just described a minimum of 0.15 ms after /NMI went low. I allowed 20 - 19.7 = 0.3 ms overhead to be safe.

I had to use two CTC channels for ~50 Hz interrupts as the ~20 ms period is more than the maximum timer interval of ~16 ms for one channel at 4 MHz. At least I could avoid ~100 Hz interrupts.
Last edited by Tony Brewer on 20 Oct 2018 01:35, edited 1 time in total.

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Re: Thoughts on Einstien "Stolen" Software?

Post by 1024MAK » 19 Oct 2018 16:33

Very clever 8-)

How long did working all this out take?

Mark

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Re: Thoughts on Einstien "Stolen" Software?

Post by Tony Brewer » 27 Oct 2018 14:41

Mark, it was taken aback but once I realised there was a solution it didn't take very long. All done the same day, I think.

Instead of one of C/T0, C/T1 or C/T2 tied to /VDPINT they are all connected to 2 MHz - a strange design decision.

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