The only two LucasArts adventure games that run well on a 4.77 mhz PC/XT 8088 (and probably PC JR) are the low resolution versions of Maniac Mansion and Zak Mckracken. The rule of thumb seems to be games that require a minimum of 256kb RAM and less run at full speed on an 8088. When you start getting into games that require 384kb or 512kb, that's when things start slowing down.

It's also very misleading because game companies put out 8088/8086 requirement on most games until 1990, even though many of them would be barely playable on an 8088 in practice. Playing Secret of Monkey Island on an 8088 is torture, but there it is on the front of the box.

I've been trying to patch a few games for the PCjr to get additional colors. Has anyone had success with Ultima 4? I ran the patch found here and started the game with "ultima t" which I read somewhere starts the game in Tandy mode. When I do that, I do get more colors, but every other "line" on the screen seems to be missing or black. Curious if anyone ever had success with 16 colors on a PCjr for Ultima 4.

It does not appear like there is a repository for patched PCjr games, although I would like to make one.

Ice Cream Jonsey wrote on 2022-09-29, 18:28:

I ran the patch found here and started the game with "ultima t" which I read somewhere starts the game in Tandy mode. When I do that, I do get more colors, but every other "line" on the screen seems to be missing or black.

That is the typical "venetian blinds" effect when trying to convert Tandy graphics to PCjr, the solution to which is to hack the game to use segment 0x1800 instead of 0xB800 f0r the video buffer. The hack can be simple or complicated, it depends on the game code.

motley6 wrote on 2014-09-29, 01:36:

It's also very misleading because game companies put out 8088/8086 requirement on most games until 1990, even though many of them would be barely playable on an 8088 in practice. Playing Secret of Monkey Island on an 8088 is torture, but there it is on the front of the box.

Barely playable was the norm back then, if you think Monkey Island was slow on an 8088

Try playing some of the graphical adventure games on c64, you move from an empty screen, expect 3-5 minutes for the next to load

motley6 wrote on 2014-09-29, 01:36:

Playing Secret of Monkey Island on an 8088 is torture, but there it is on the front of the box.

rmay635703 wrote on 2022-09-29, 23:27:

Barely playable was the norm back then, if you think Monkey Island was slow on an 8088

Secret of Monkey Island is quite playable (albeit a tad sluggish) if you've got a Turbo XT. I sure wouldn't want to play it on an original 4.77mhz PC though!

The game really was intended to run on the 8088, there are extra animations (like the pirate swinging from the chandelier in the bar) which only get enabled if the CPU is fast enough e.g. a 286 or higher.

Fastest "Turbo XT"

People on the net always seem to forget that the 8086/NEC V30 were also around. :)
These were about twice as fast at same clockspeed.

Non-"castrated"* PC compatibles and Turbo XTs also existed.
Amstrad PC1512, Olivetti M24, Tandy 1000 SL etc.

Then, there used to be 80186 PCs around, too.
Siemens PCD-D, BBC Master 512.. All from the early 80s.

They all were rudimentary CGA and BIOS compatible, at least.

If external components were used, such as PIT, PIC etc, then better IBM PC compatibility was possible with 80186 systems.

And at 8 MHz, they were comparable to slow ATs, at least.

Ergo, the stickers on those old game boxes weren't lying, really.
Games running on 8086 PCs faster than 4,77 MHz were kind of playable.

Edit: Typos fixed.

Edit: This old thread/topic is an interesting read, too.
It covered the different duty cycles of Intel/NEC, for example:
Clock doubling circuit for Turbo XT's!

Edit: Here's an article of an 7.16 MHz overclock for the IBM PC 5150.

https://ctrl-alt-rees.com/2020-12-31-my-maxed … -doscember.html

https://www.youtube.com/watch?v=Y7NNCWvt1nY

(*Sounds slightly offensive, maybe, but that's how an Intel developer called the 8088 in the day. Rightfully, imho. source )

It's also very misleading because game companies put out 8088/8086 requirement on most games until 1990, even though many of them would be barely playable on an 8088 in practice. Playing Secret of Monkey Island on an 8088 is torture, but there it is on the front of the box.

Agreed, I'm sure a lot of us were caught out more than once in our eagerness and lack of budget to play the latest titles, so we bought into the 'Minimum System Requirements' - happily today we can see what all the fuss was about unless our memories are too tarnished from our first experiences 😀

To add to the list of more serious strategy offerings that ran well on an 8088/8086/V20, there was Avalon Hill's Diplomacy and The Ancient Art of War. Both were great games that ran in CGA or Hercules (with a CGA simulator like HGCIBM or SIMCGA) - I'm not sure if they run on a PCjr though!

Accolade Grand Prix Circuit