The attached ZAKJR executable fixes the off-center screen and the composite colors. The output looks just like the photo I took of the Tandy 1000 SX's composite color output. The RGBI colors look fine too.

Oh, and because I hate having to ask people to hack everything for me, I have attached the executable for Maniac Mansion, which also has this problem and has been fixed for the PCjr. using NRS' hack, the file compare command with the binary switch and a hex editor.

This hacking of Maniac Mansion and Zak has only peripheral relevance to DOSBox and the composite patch, and is better joined to the thread where the hacking was first discussed.

To clarify, none of these hacks are needed for DOSBox (just use the Tandy machine type); and a real PCjr must be upgraded with a memory "sidecar" expansion in order to run the games, hacked or not.

And you will need to run a program like King's Quest I or tdyspkr.com to enable the external sound output, or you will hear nothing from these hacked games on a PCjr.

This leads me to the question: What is the point of setting BIOS mode 4 then doing tens of manual I/O writes when you could just set BIOS mode 8 and be done with it? Silly LucasArts.

Great Hierophant wrote:

And you will need to run a program like King's Quest I or tdyspkr.com to enable the external sound output, or you will hear nothing from these hacked games on a PCjr.

You could use the bypassed Tandy register writes as "patch space" to enable output from the sound chip:

1mov ax,8003h
2int 1ah

or, if you prefer a more direct approach:

1in  al,61h
2or  al,60h
3out 61h,al

I have updated ZAKJR.EXE to incorporate the external sound output enable code.

NewRisingSun wrote:

I have updated ZAKJR.EXE to incorporate the external sound output enable code.

I checked the differences between the current and prior executable, and the changes make sense except why the change of two bytes at 0x12 and 0x13?

I made the appropriate changes to Maniac Mansion, except those bytes, and it Maniac works and enables the external sound. So does your Zak patch. I uploaded this new Maniac modification above.

why the change of two bytes at 0x12 and 0x13?

That field in the EXE header is a checksum of all the non-overlay bytes in the EXE file. It's not terribly important, and most linkers don't set it at all, but Zak's apparently did, so I recalculated it after patching for consistency.

@ OP, and everyone else with the same specific requirement

Offsets for 1993 MANIAC.EXE (non-enhanced & bundled with DOTT) are 751 & 752 (hex). Change BB FF to EB 19 and you're done.
And set tandy=on (true does nothing) in your .conf.

Ty ripsaw for EB 19!