VOGONS


Reply 20 of 27, by VileR

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^ That's true. The Jr. was the slowest member of the PC family (mostly due to its memory architecture), so most speed-sensitive PCjr games need a very low cycle count in DOSBox. Sometimes down to 150 or so.

PCem is another emulator that does PCjr, but DOSBox is much more convenient when you need to go through a large pile of software quickly, and it's very much compatible with PCjr stuff as long as you configure "machine=" and "cycles=" correctly.

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Reply 21 of 27, by kikendo

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Jorpho wrote on 2020-06-12, 17:30:
kikendo wrote on 2020-06-12, 17:15:

I tested it with Dosbox on the old Pentium, and everything was too fast, unplayable or simply didn't work.

Generally, there's really no point to using DOSBox on an old Pentium instead of on a modern PC, especially if you're working with disk images. Regardless of what kind of computer you're using, you can slow DOSBox down almost as much as you want, mainly by decreasing the number of cycles or by changing the machine type – it would be useless for the oldest games otherwise.

Then I guess I don't know how to use Dosbox. I also tried on my modern computer. I told it to use the slowest CPU but it was still to fast. How many cycles am I supposed to set for IBM PCjr-like performance?

This is till failing when things like a PCjr cartridge is required. An IBM PCjr emulator would be the best option here.

Reply 22 of 27, by Jorpho

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kikendo wrote on 2020-06-14, 23:52:

Then I guess I don't know how to use Dosbox. I also tried on my modern computer. I told it to use the slowest CPU but it was still to fast.

Well, how exactly did you tell it to do that?

This is till failing when things like a PCjr cartridge is required. An IBM PCjr emulator would be the best option here.

I feel like I've read about emulators for cartridge ROMs before. MAME (formerly MESS), maybe? Or https://bitbucket.org/hdk_2/5511emu/src/master/ ?

Reply 23 of 27, by kikendo

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Jorpho wrote on 2020-06-15, 03:40:

Well, how exactly did you tell it to do that?

I edited the .ini file of course. But I didn't mess with the cycles because I don't know what I am doing with that.

I feel like I've read about emulators for cartridge ROMs before. MAME (formerly MESS), maybe? Or https://bitbucket.org/hdk_2/5511emu/src/master/ ?

I'll look at MAME. Never thought of it.

Reply 25 of 27, by kikendo

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Jorpho wrote on 2020-06-15, 15:40:
kikendo wrote on 2020-06-15, 04:34:

I edited the .ini file of course.

Of course, yes, but what did you edit?

as I said already, I did NOT add a value to the "cycles" setting which is what you said I should be editing. I only told it to use 386_SLOW under CPUTYPE, and then set CYCLES to AUTO.

Reply 26 of 27, by kikendo

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OK I went and changed DOSBox config to use 1000 cycles, which looked like about a good speed on Flight Simulators, but IBM PCjr-specific software will STILL not run, always exiting with various errors.
I can't even run BASICA.COM to run IBM PCjr BASIC software.
I'll have to look into the options mentioned above, DOSBox just doesn't work.

Reply 27 of 27, by Jorpho

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Thank you for that clarification. (In fact, the DOSBox configuration is stored in DOSBox.conf, so actually I'm not entirely certain what you mean by "editing the .ini", either. Are you using some kind of frontend?)

As noted in the earlier post, instead of changing the "cputype" setting, did you try changing the "machine=" setting to "pcjr"?

Also as noted in that post, cycles=150 may be appropriate for PCjr. As noted in the DOSBox readme, you can press CTRL-F11 to decrease the number of cycles while DOSBox is running instead of setting it directly in DOSBox.conf.

And as also noted in the DOSBox readme, the "boot" command can be used to load PCjr cartridges if the "pcjr" machine type is set, though "support is still limited". (I knew I had read about that somewhere.)